ETOPS – Extended-range Twin-engine Operational Performance Standards


ETOPS is an acronym for Extended-range Twin-engine Operational Performance Standards, an International Civil Aviation Organization (ICAO) rule permitting twin-engine commercial air transporters to fly routes that, at some points, are farther than a distance of 60 minutes’ flying time from an emergency or diversion airport with one engine inoperative.

This rule allows twin-engine airliners—such as the Airbus A300, A310, A32X, A330 and A350 families, and theBoeing 737, 757, 767, 777 and 787—to fly long-distance routes that were previously off-limits to twin-engine aircraft. ETOPS operation has no direct correlation to water or distance over water. It refers to single-engine flight times between diversion airfields—regardless as to whether such fields are separated by water or land.



Early ETOPS experience

The FAA and the ICAO concluded that it is safe for a properly designed twin-engined airliner to conduct intercontinental transoceanic flights. The guidelines issued form the ETOPS regulations.

The FAA was the first to approve ETOPS guidelines in 1985. It spelled out conditions that need to be fulfilled for a grant of 120 minutes’ diversion period, which is sufficient for direct transatlantic flights. Today, ETOPS forms the bulk of transatlantic flights.

The FAA gave the first ETOPS rating in May 1985 to TWA for the B767 service between St. Louis andFrankfurt, allowing TWA to fly its aircraft up to 90 minutes away from the nearest airfield: this was later extended to 120 minutes after a federal evaluation of the airline’s operating procedures.



ETOPS extensions

In 1988, the FAA amended the ETOPS regulation to allow the extension to a 180-minute diversion period subject to stringent technical and operational qualifications. This made 95% of the Earth’s surface available to ETOPS flights. The first such flight was conducted in 1989. This set of regulations was subsequently adopted by the Joint Aviation Authorities (JAA), ICAO and other regulatory bodies.

In this manner the B737, 757 and 767 series and the Airbus A300-600, 310, 320 and 330 series were approved for ETOPS operations. The success of ETOPS aircraft like 767 and 777 killed the intercontinental trijets. This ultimately led Boeing to end the MD-11 program a few years after Boeing’s merger with McDonnell Douglas, as well as to scale down the production of its own Boeing 747.

The cornerstone of the ETOPS approach are the statistics that show that the turbine itself is an inherently reliable component, and it is the engine ancillaries that have a lower reliability rating. Therefore an engine for a modern twin jet airliner has twin sets of all ancillaries mounted in the engine, which gives the required reliability rating.

The North Atlantic airways are the most heavily used oceanic routes in the world. Most North Atlantic airways are covered by ETOPS 120-minute rules, removing the necessity of using 180-minute rules. However, many of the North Atlantic diversion airports, especially those in Iceland and Greenland, are subject to adverse weather conditions making them unavailable for use. As the 180-minute rule is the upper limit, the JAA has given 15% extension to the 120-minute rules to deal with such contingencies, giving the ETOPS-138min, thereby allowing ETOPS flights with such airports closed.

ETOPS240 and beyond are now permitted[1] on a case-by-case basis, with regulatory bodies in nations ranging from the USA, to Australia, to New Zealand adopting said regulatory extension. Authority is only granted to operators of two-engine airplanes between specific city pairs. The certificate holder must have been operating at 180 minute or greater ETOPS authority for at least 24 consecutive months, of which at least 12 consecutive months must be at 240-minute ETOPS authority with the airplane-engine combination in the application.




The regulations allow an airliner to have ETOPS-120 rating on its entry into service. ETOPS-180 is only possible after 1 year of trouble-free 120-minute ETOPS experience. Boeing has convinced the FAA that it could deliver an airliner with ETOPS-180 on its entry into service. This process is called Early ETOPS. Thus the B777 was the first aircraft to carry an ETOPS rating of 180 minutes at its introduction.

The JAA, however disagreed and the Boeing 777 was rated ETOPS-120 in Europe on its entry into service. European airlines operating the 777 must demonstrate one year of trouble-free 120-minutes ETOPS experience before obtaining 180-minutes ETOPS for the 777.



ETOPS exclusions

Private jets are exempted from ETOPS by the FAA, but are subject to the ETOPS 120-minute rule in JAA’s jurisdiction. Several commercial airline routes are still off-limits to twinjets because of ETOPS regulations. There are routes traversing the South Pacific (e.g. Auckland,New Zealand – Santiago, Chile), Southern Indian Ocean (e.g. Perth, Western Australia -Johannesburg, South Africa) and Antarctica.



Beyond ETOPS-180

Effective February 15, 2007, the FAA ruled that US-registered twin-engined airplane operators can fly over most of the world other than the South Polar Region, a small section in the South Pacific, and the North Polar area under certain winter weather conditions provided that the inflight shutdown rate is 1 in 100,000 engine hours. This limit is more stringent than ETOPS-180 (2 in 100,000 engine hours).

The qualified aircraft must have appropriate fire-suppression systems, adequate oxygen supplies for crew and passengers (to continue high altitude flight) in the event of depressurisation, and automated defibrillators. Weather reporting, training, and diversion accommodation requirements remain unchanged. Since aircraft occasionally divert for non-engine mechanical problems or passenger medical emergencies, the rule requires that airplane systems be able to support lengthy diversions in remote and sometimes harsh environments. The rules do not apply to 3- or 4-engined cargo aircraft or twinjets freed from ETOPS constraints.

EASA distinguishes between twin-engine (ETOPS) and aircraft with 3 or 4 engines. Rules governing such aircraft (3 or 4 engines) are covered under LROPS rules. LROPS would demand similar rules with regard to emergency oxygen and fire-suppression. EASA is expected to release rules for ETOPS and LROPS in 2008.



ETOPS ratings

The following ratings are awarded under current regulations according to the capability of the airline:

  • ETOPS-75
  • ETOPS-90
  • ETOPS-120/138
  • ETOPS-180/207

However, ratings for ETOPS type approval are fewer. They are:

  • ETOPS-90, which keeps pre-ETOPS Airbus A300B4 legally operating under current rules
  • ETOPS-120/138
  • ETOPS-180/207, which covers 95% of the Earth’s surface.



Approval for ETOPS

ETOPS approval is a two-step process. Firstly: the airframe and engine combination must satisfy the basic ETOPS requirements during its type certification. This is called ETOPS type approval. Such tests may include shutting down an engine and flying the remaining engine during the complete diversion time. Often such tests are performed in the middle of the oceans. It must be demonstrated that, during the diversion flight, the flight crew is not unduly burdened by extra workload due to the lost engine and that the probability of the remaining engine failing is extremely remote. For example, if an aircraft is rated for ETOPS-180, it means that it should be able to fly with full load and just one engine for 3 hours.

Secondly: An operator who conducts ETOPS flights must satisfy his own country’s aviation regulators about his ability to conduct ETOPS flights. This is called ETOPS operational certification and involves compliance with additional special engineering and flight crew procedures on top of the normal engineering and flight procedures. Pilots and engineering staff must be qualified and trained for ETOPS. An airline with extensive experience operating long distance flights may be awarded ETOPS operational approval immediately, others may need to demonstrate ability through a series of ETOPS proving flights.

Regulators closely watch the ETOPS performance of both type certificate holders and their affiliated airlines. Any technical incidents during an ETOPS flight must be recorded. From the data collected , the reliability of the particular airframe-engine combination is measured and statistics published. The figures must be within limits of type certifications. Of course, the figures required for ETOPS-180 will always be more stringent than ETOPS-120. Unsatisfactory figures would lead to a downgrade, or worse, suspension of ETOPS capabilities either for the type certificate holder or the airline.




Aircraft Polar Route Operations

Polar Route Operations

A. Introduction

1. New cross-polar routes connect eastern and interior regions of North America to Asian cities via Polar Region which provides an attractive shortcut to Asia (Polar 1, 2, 3 and 4).

2. The advantages are obvious; it reduces the flight time, increase the payload and also there is the absence of turbulence.

3. Polar routes operate under extreme temperatures in the Artic environment where suitable and alternate airports are limited.

4. There are many major Airlines operating the polar routes, notably United, Continental, Northwest, Delta, Air Canada. Air China, Russia KrasAir and Cathay Pacific.

5. The following should be considered when conducting polar routes operation:
A) Regulatory guidance
B) En route alternate airport
C) Cold fuel management
D) Communication and navigation

B. Regulatory guidance

1. Obtain info from local authority and FAA on the specific requirement to conduct polar operations i.e. approval and to provide flight plan – Flight Ops

2. Prepare the Airline Recovery Plan for unplanned diversion that address the care & safety of crew at the diversion airport and provide the plan to transport crew from that airport – Flight Ops

3. Prepare the Long Range Flight Crew Rest Plan and a clear progression of pilot-in-command authority – Flight Ops

4. Liaise with Boeing to develop a Fuel temperature analysis and monitoring program – Engineering

5. Verify that acft is fitted with effective communication system i.e. VHF(Voice and data link), HF(Primary) & SATCOM (Back-up) – Engineering

6. Amend Minimum Equipment Lists (MEL) to indicate the following equip/systems are required for north polar operations dispatch – Engineering
1) FQIS (include fuel tank temperature indicating system)
2) Auto-throttle system
3) Autopilot
4) Communication systems i.e. HF and VHF (Voice & ACARS), (SATCOM – backup system)

7. Conduct training for flight crew and maintenance on Polar Route Operation (i.e. QFE, QNH and meter altimetry, cold temp alt correction proc, fuel management proc, weather pattern and cold weather anti-exposure suits) – Flight Ops and Engineering

8. Ensure a minimum of two (2) cold weather anti-exposure suits to be on board the acft – Engineering

9. Conduct an DCA-observed validation flight in order to receive authorization to conduct polar operations – Flight Ops

10. In the event of any emergency landing for aircraft flying over substantially uninhabited land areas in polar conditions are likely to be met MCAR scale V, which requires the following:
1) One survival beacon radio apparatus,
2) Marine type pyrotechnical distress signal
3) 100 gm of glucose toffee tablets for each 4 persons on board
4) Half liter of fresh water in durable containers for each 4 persons on board
5) First aid equipment
6) One stove suitable for use with acft fuel for every 75 persons
7) One cooking utensil in which snow or ice can be melted, two snow shovels and two ice saws
8) Single or multiple sleeping bags
9) Artic survival kit

C. En Route Alternate Airports

1. Flight Ops to identify the alternate airports along a routes which must have
a capability such as airplane can land safely at the existing runway, diverted airplane can be cleared from the runway, crew are able to deplane in a safe manner, facilities near the airport and recovery plan can be executed and completed within 12 to 48 hrs after diversion – Flight Ops

D. Cold Fuel Management

1. Verify that MD-11 is fitted with fuel temperature probe located in the outboard compartment of tank no 3 and in the horizontal stabilizer tank and Low Fuel Temperature indicator is displayed on Display Unit – Engineering

E. Communication and Navigation

1. Polar route operations require VHF and HF systems to communicate with ATC. SATCOM should be considered only as a backup as it is not available above 82 deg north latitude.

2. Aircraft entering Russian airspace on Polar 1 and Polar 2 are controlled by the Murmansk ATC center near the Finnish border and those entering Polar 3 and Polar 4 are under Magadan’s watch located in Russia’s east coast.

3. GPS and IRUs provide navigation over the polar route. Aircraft is recommended to equipped with dual GPS and triple IRUs; which is fitted on MD11.

i) Aero Magazine of Oct 2001
ii) OPSPEC B055 on North Polar Operations in the Air Transport Operations Inspectors Handbook Order 8400.10, Volume 3
iii) Civil Aviation Regulations (CAR)

Fuel Boost Pump Wire Chafing

Title: Fuel Boost Pump Wire Chafing

Aircraft Model: 737-100,-200,-300,-400,-500
Other Models: 707, 727

Issue Status: Open
Applicability: All 737-200/-300/-400/-500 airplanes

During the first repeat inspection after initial inspection per AD 99-21-15 and SB 737-28A1120, the #1 aft (left wing tank) fuel boost pump wiring of a 737-300 airplane was found with chafing through the Teflon sleeving into wiring insulation at three different locations. Approximately 21000 hours had accumulated since the wire bundle was initially replaced.

Boeing considers this an Airplane Level safety issue because chafing completely through the wire insulation may cause arcing within the conduit and possible burn through, leading to a potential ignition source.

In a 727 incident under investigation by the Indian government, wire bundle damage was discovered in the fuel tank conduit after an explosion that occurred on the ground in the left wing fuel tank. Approximately 10000 hours had accumulated since incorporation of AD 99-12-52. It is not known if chafing played a role in the 727 event.

Airworthiness Directives 99-21-15 (737), 99-12-52 (727) and 2001-17-20 (707) require removal of the fuel boost pump wiring from the in-tank conduit(s) for the boost pumps in main tanks number 1 and 2, and the center tank boost pumps, and a detailed visual inspection to detect damage of the wiring in accordance with Boeing alert service bulletins 737-28A1120, 727-28A0126 and 707A3500. These ADs also require repeat inspections, at intervals not to exceed 30,000 flight hours after accomplishment of the initial inspection. The 737 Classic aircraft have four conduits with wire bundles running to the fuel pumps; the 727 has eight and the 707 has ten.

Boeing is continuing to expedite root cause investigation including removal of the 737 aircraft conduit from the in-service aircraft for laboratory investigation.

The FAA has opened a planned AD worksheet. An FAA Immediately Adopted Rules (IAR) is anticipated to mandate the interim action that Boeing defines via service bulletin 737-28A1263(ECD TBD).

Compliance time is to be determined taking into consideration risk mitigation, operator impact and very large fleet size. To date, a compliance time of 90-120 days has been suggested by the FAA for the interim action, to be finalized based on parts availability, etc.

Boeing does not plan to release a service bulletin until parts are available.

Interim Action:
Boeing plans to address the 737 Classic first, immediately followed by 727. The 707 is also under review.

Accomplish within 90-120 days (to be confirmed) after new service bulletin and parts are available:

1- Remove and inspect all fuel boost pump wiring from the boost pump connectors to the splices on the front wing spar

2- Replace all Teflon sleeving with sleeving which has smaller OD than the conduit ID.

3- Replace all four conductor, unjacketed, or BMS13-51 wires with BMS13-60 jacketed wiring. Remove ground wire if found installed.

4- If any wire damage or arcing indications are found, inspect conduit (boroscope), leak check per AMM, and repair or replace the conduit.

5- Clean inside of conduit prior to installing the reworked/new wire bundle.

Do not use talcum powder as a wire pulling lubricant. S/B will specify the type of lubricant(s) to use

Report all inspection results to Boeing

Operator Action:
Incorporate service bulletin 737-28A1263 (when released), report all inspection results to Boeing, and comment on the FTEI bulletin board item EM-06-00063 with relevant information, if available.

Part Information:
Boeing is planning parts kits consisting of a roll of wire and a roll of sleeving in airplane ship set quantity.

A limited supply of miscellaneous parts will also be available at Boeing (separate from the kits) to support this inspection (conduits, connectors, splices, contacts, etc.).

Service Related Problem (SRP) 727-SRP-28-0113
Service Related Problem (SRP) 737-SRP-28-0113
Fleet Team Emerging Issue (FTEI) EM-06-00063, dated 06-JUL-2006
Airworthiness Directive (AD) 99-12-52 (727)
Airworthiness Directive (AD) 99-21-15 (737)
Service Bulletin (SB) 737-28A1120, dated 24-APR-1998

Aviation Safety – Determination of an Unsafe Condition

Aviation Safety – Determination of an Unsafe Condition

It is important to note that these guidelines are not exhaustive.  However, this material is intended to provide guidelines and examples that will cover most cases, taking into account the applicable certification requirements.


Certification or approval of a product, part or appliance is a demonstration of compliance with requirements which are intended to ensure an acceptable level of safety.  This demonstration however includes certain accepted assumptions and predicted behaviours, such as:

–           fatigue behaviour is based on analysis supported by test,

–           modelling techniques are used for Aircraft Flight Manual performances calculations,

–           the systems safety analyses give predictions of what the systems failure modes, effects and probabilities may be,

–           the system components reliability figures are predicted values derived from general experience, tests or analysis,

–           the crew is expected to have the skill to apply the procedures correctly, and

–           the aircraft is assumed to be maintained in accordance with the prescribed instructions for continued airworthiness (or maintenance programme), etc.

In service experience, additional testing, further analysis, etc., may show that certain initially accepted assumptions are not correct.  Thus, certain conditions initially demonstrated as safe, are revealed by experience as unsafe.  In this case, it is necessary to mandate corrective actions in order to restore a level of safety consistent with the applicable certification requirements.


The following paragraphs give general guidelines for analysing the reported events and determining if an unsafe condition exists, and are provided for each type of product, part or appliance subject to a specific airworthiness approval: type-certificates (TC) or Design Changes for aircraft, engines or propellers, or Technical Standard Orders (TSO).

This analysis may be qualitative or quantitative, i.e. formal and quantitative safety analyses may not be available for older or small aircraft.  In such cases, the level of analysis should be consistent with that required by the airworthiness requirements and may be based on engineering judgement supported by service experience data.

2.1       Analysis method for aircraft.

2.1.1   Accidents or incidents without any aircraft, engines, system, propeller or part or appliance malfunction or failure.

When an accident/incident does not involve any component malfunction or failure but when a crew human factor has been a contributing factor, this should be assessed from a man-machine interface standpoint to determine whether the design is adequate or not.  Paragraph 2.5 gives further details on this aspect.

2.1.2   Events involving an aircraft, engines, system, propeller or part or appliance failure, malfunction or defect.

The general approach for analysis of in service events caused by malfunctions, failures or defects will be to analyse the actual failure effects, taking into account previously unforeseen failure modes or improper or unforeseen operating conditions revealed by service experience.

These events may have occurred in service, or have been identified during maintenance, or been identified as a result of subsequent tests, analyses, or quality control.

These may result from a design deficiency or a production deficiency (non conformity with the type design), or from improper maintenance.  In this case, it should be determined if improper maintenance is limited to one aircraft, in which case an airworthiness directive may not be issued, or if it is likely to be a general problem due to improper design and/or maintenance procedures, as detailed in paragraph 2.5.

  1. A)        Flight.

An unsafe condition exists if:

–           There is a significant shortfall of the actual performance compared to the approved performance (taking into account the accuracy of the performance calculation method), or

–           The handling qualities, although having been found to comply with the applicable airworthiness requirements at the time of initial approval, are subsequently shown by service experience not to comply.

  1. B)        Structural or mechanical systems.

An unsafe condition exists if the deficiency may lead to a structural or mechanical failure which:

–           Could exist in a Principal Structural Element that has not been qualified as damage tolerant.  Principal Structural Elements are those which contribute significantly to carrying flight, ground, and pressurisation loads, and whose failure could result in a catastrophic failure of the aircraft.

–           Could exist in a Principal Structural Element that has been qualified as damage tolerant, but for which the established inspections, or other procedures, have been shown to be, or may be, inadequate to prevent catastrophic failure.

–           Could reduce the structural stiffness to such an extent that the required flutter, divergence or control reversal margins are no longer achieved.

–           Could result in the loss of a structural piece that could damage vital parts of the aircraft, cause serious or fatal injuries to persons other than occupants.

–           Could, under ultimate load conditions, result in the liberation of items of mass that may injure occupants of the aircraft.

–           Could jeopardise proper operation of systems and may lead to hazardous or catastrophic consequences, if this effect has not been taken adequately into account in the initial certification safety assessment.

  1. C)        Systems.

The consequences of reported systems components malfunctions, failures or defects should be analysed.

For this analysis, the certification data may be used as supporting material, in particular systems safety analyses.

The general approach for analysis of in service events caused by systems malfunctions, failures or defects will be to analyse the actual failure effects.

As a result of this analysis, an unsafe condition will be assumed if it cannot be shown that the safety objectives for hazardous and catastrophic failure conditions are still achieved, taking into account the actual failure modes and rates of the components affected by the reported deficiency.

The failure probability of a system component may be affected by:

–           A design deficiency (the design does not meet the specified reliability or performance).

–           A production deficiency (non conformity with the certified type design) that affects either all components, or a certain batch of components.

–           Improper installation (for instance, insufficient clearance of pipes to surrounding structure).

–           Susceptibility to adverse environment (corrosion, moisture, temperature, vibrations etc.).

–           Ageing effects (failure rate increase when the component ages).

–           Improper maintenance.

When the failure of a component is not immediately detectable (hidden or latent failures), it is often difficult to have a reasonably accurate estimation of the component failure rate since the only data available are usually results of maintenance or flight crew checks.  This failure probability should therefore be conservatively assessed.

As it is difficult to justify that safety objectives for the following systems are still met, a deficiency affecting these types of systems may often lead to a mandatory corrective action:

–           back up emergency systems, or

–           fire detection and protection systems (including shut off means).

Deficiencies affecting systems used during an emergency evacuation (emergency exits, evacuation assist means, emergency lighting system …) and to locate the site of a crash (Emergency Locator Transmitter) will also often lead to mandatory corrective action.

  1. D)        Others.

In addition to the above, the following conditions are considered unsafe:

–           There is a deficiency in certain components which are involved in fire protection or which are intended to minimise / retard the effects of fire / smoke in a survivable crash, preventing them to perform their intended function (for instance, deficiency in cargo liners or cabin material leading to non-compliance with the applicable flammability requirements).

–           There is a deficiency in the lightning or High Intensity Radiated Fields protection of a system which may lead to hazardous or catastrophic failure conditions.

–           There is a deficiency which could lead to a total loss of power or thrust due to common mode failure.

If there is a deficiency in systems used to assist in the enquiry following an accident or serious incident (e.g., Cockpit Voice Recorder, Flight Data Recorder), preventing them to perform their intended function, the DCA may take mandatory action.

2.2       Engines.

The consequences and probabilities of engine failures have to be assessed at the aircraft level in accordance with paragraph 2.1, and also at the engine level for those failures considered as Hazardous in the design code such as CS E-510 or FAR 33.

The latter will be assumed to constitute unsafe conditions, unless it can be shown that the consequences at the aircraft level do not constitute an unsafe condition for a particular aircraft installation.

2.3       Propellers.

The consequences and probabilities of propeller failures have to be assessed at the aircraft level in accordance with paragraph 2.1, and also at the propeller level for those failures considered as hazardous in the design code such as CS P-150.

The latter will be assumed to constitute unsafe conditions, unless it can be shown that the consequences at the aircraft level do not constitute an unsafe condition for a particular aircraft installation.

2.4       Parts and appliances.

The consequences and probabilities of equipment failures have to be assessed at the aircraft level in accordance with paragraph 2.1.

2.5       Human factors aspects in establishing and correcting unsafe conditions.

This paragraph provides guidance on the way to treat an unsafe condition resulting from a maintenance or crew error observed in service.

It is recognised that human factors techniques are under development.  However, the following is a preliminary guidance on the subject.

Systematic review should be used to assess whether the crew or maintenance error raises issues that require regulatory action (whether in design or other areas), or should be noted as an isolated event without intervention.  This may need the establishment of a multidisciplinary team (designers, crews, human factors experts, maintenance experts, operators etc.)

The assessment should include at least the following:

–           Characteristics of the design intended to prevent or discourage incorrect assembly or operation;

–           Characteristics of the design that allow or facilitate incorrect operation,

–           Unique characteristics of a design feature differing from established design practices;

–           The presence of indications or feedback that alerts the operator to an erroneous condition;

–           The existence of similar previous events, and whether or not they resulted (on those occasions) in unsafe conditions;

–           Complexity of the system, associated procedures and training (has the crew a good understanding of the system and its logic after a standard crew qualification programme?);

–           Clarity/accuracy/availability/currency and practical applicability of manuals and procedures;

–           Any issues arising from interactions between personnel, such as shift changeover, dual inspections, team operations, supervision (or lack of it), or fatigue.

Apart from a design change, the corrective actions, if found necessary, may consist of modifications of the manuals, inspections, training programmes, and/or information to the operators about particular design features.  The local authority i.e. DCA may decide to make mandatory such corrective action if necessary.

Design Organization Approval (DOA)

Design Organization Approval (DOA)

Part 1 – Obligation to the international requirements to ensure aviation safety


2) MCAR Regulation 27 – A certificate of airworthiness issued in respect of an aircraft shall cease to be in force if the aircraft, or such of its equipment as is necessary for the airworthiness of the aircraft, is overhauled, repaired or modified, or if any part of the aircraft or of such equipment is removed or is replaced otherwise than in a manner and with material of a type approved by the Director General either generally or in relation to a class of aircraft or to the particular aircraft.

Part 2 – Design Approval

1) Modification and Repair per ICAO Document 9760




• CAR 1996 Regulation 27 para 7 stated aircraft C of A become invalid, if the design change does not comply with the required airworthiness requirements.

2) Design Organization Approval (DOA)

• The local authority i.e. DCA / DGCA is not a Design Organization. Therefore DCA / DGCA cannot accept responsibility for the design.

• DOA is approval for an organization to provide reports and certify that the design of an acft, equipment or any part thereof or modification or repair schemes complies with DCA / DGCA requirements.

• JAR/EASA 21 – SUBPART J (DESIGN ORGANIZATIONS APPROVAL). The principles of both JAR/EASA and BCAR are similar. However, JAR/EASA has been developed more comprehensive than BCAR, i.e. Design Assurance System has been introduced in JAR/EASA.

• Benefit being approved as DOA is being granted privileges with responsibilities and may perform certification and airworthiness activities on behalf of DCA through the following granted privileges:

– Release certification documents without verification by DCA / DGCA
– Classify modifications and repairs
– Approve minor modifications and repairs
– DOA may issue information or instructions stating that the technical content is approved.
– For Modifications undertaken by organisations that are appropriately approved for the task and who have demonstrated a consistent and satisfactory level of competence for the type of work involved, then future similar Modifications may be classified as Minor by the DCA / DGCA.
– Efficient use of industry and DCA / DGCA time, resulting in lower costs.

• DOA shall be headed by an Accountable Manager (Chief Executive or Equivalent) and with full efficient coordination between their units/sections.

• Scope of work – The organization must have
– sufficient personnel with the right qualification, knowledge and experience.
– appropriate tools (Software), equipments (computer) and facility (i.e. office space, lab, flight test center)

3) Design Organization Manual (DOM)

• Policy/procedure of carrying out design activities and management of DOA
– Classification of Major/Minor
– Development of reports/drawings/Test Schedule
– Verification of Design Data
– Inservice difficulty reporting
– Correction action
– Internal Audit
– Retention of designs records
– Design Assurance systems (DAS)

4) Design Assurance System (DAS)

• A DOA shall demonstrate that it has established and is able to maintain a Design Assurance System (DAS) for the control and supervision of the design, and of design changes, of products, parts and appliances covered by the approval.

• The DAS shall be such as to enable the organization;
– To ensure the design of the products, parts and appliances or the design changes thereof, comply with the applicable type certification basis.
– Ensure that its responsibilities are properly discharged.
– Independently monitor the compliance with, and adequacy of, the documented procedures of the system (DOM). The monitoring shall include a feed back system to a person having the responsibilities to ensure corrective actions.

• DAS shall include an independent checking function of the showing of compliance on the basis of which the organization submits compliance statement and associated document to DCA / DGCA.

Part 3 – Certification of Modification/Repair

1) A modification or repair must meet two standards; the acft type certification rules and the performance rules.

2) Data Package is a set of documents required for the justification / accomplishment of the modification such as:

• Standard documents; i.e. Certification plan (for complex modification), Modification documents, SOC, CCD (if applicable) and Manuals amendments (if applicable)

• Type Design documents ; i.e. Drawings, Specifications, Information on dimensions, materials and processes, Airworthiness limitations and any other data necessary to describe the modification.

• Substantiating data; i.e. Test and analysis reports and Justification reports

3) Approved Data is a data which has been investigated and approved by an acceptable authority such as FAA, JAA and UK CAA and divided into two categories:- OEM data and Non OEM data.

• The data packages are only considered as an approved data provided the limitations, including applicability of an approved data are met.

4) FAA Form 8110-3 approved by FAA Designated Engineering Representatives (DER) i.e. OEM DER is accepted as approved data but require DCA installation approval. Consultants DER require review because it has similar status as the Non-OEM STCs.

5) Statement of Compliance (SOC) is a form used as the top-level document for the data package. SOC form shall be signed by a Design Approval signatory or authorized person.


B727 & B737 Window Heat Controller


A) Reason for the study


1)       B727/737 Window heat controller unit (WHCU) p/n 231-2 (alt p/n 65-52803-8, 83000-05602, 10-61833-2) was among the top 5 unscheduled component removal for 4 consequences months from Nov 2007 till Feb 2008.  These studies analyze common reasons of such failures from year 2005 till Nov 2007 to enhance its reliability.

2)       There are various P/Ns (various OEMs) of Window Heat Controller Unit (WHCU) installed on B727/B737. All P/Ns are fully interchangeable.


Boeing P/N





83000-05601 / -05602





BAE Systems

3)       There were 4 units of WHCU installed on 727 (and B737) airplane which for pilot and co-pilot No. 1 and No. 2 windows. The WHCU located at E5-1 electrical rack. It consists of temp controller which a solid state device that performs overheat control and temp control, overheat relay which direct 115V AC power from window heat CB to temp controller when energized and transformer which provide high voltage for heating window.



B) Data

1)       Repair and Findings Data from 1st Jan 2005 till 31st May 2008 were reviewed and has been classified into various types of common defect and shop findings; s/n and aircraft with repeated removals. Total 43 units were removed unscheduled with 30 DC and 13 DNC. None were scrapped or overhauled.

Defect Confirm

Defect Not Confirm

30 (69.8 %)

13 (30.2%)

2)       Unscheduled removals unit in 2005, 2006, 2007 and 2008 (till May) are shown below:





2008 (till May)

Removal Units





3)       MTBUR for B737 is 2935 hrs and for B727 is 4112 hrs. The average MTBUR is 3838 hrs. Design MTBUR for WHCU p/n 83000-05602 is 14046 hrs while MTBF is 29200 hrs.

C) Current Maintenance Program




Every ‘C’ chk (Card: C-102A-2)

Every ‘C’ chk            (Card: 72C1-E-2-4-016)

Inspect cabin control window anti-icing syst for components such as window heat power relay, anti-ice control panel, heat conductive coating, thermal switches and heat sensors for security, wiring condition and evidence of overheat.

Every ‘C’ chk (Card: C-103A-1)


Inspect window heat control unit (4 places) installed on the E3 rack for security of installation, condition of wiring, cleanliness and evidence of overheat / moisture.


D) OEM comments.

Email from Boeing and OEM are described below:

1)        Boeing via email dated April, 30 and May, 9 provided comments per below:

  1. a) Boeing has not received any reports from other operator similar to WHCU defects.
  2. b) Boeing provides current MTBF reported from Koito is 29200 hrs.
  3. c) Boeing has limited knowledge of the Astronics p/n 231-5 due to this is an STC mod and therefore the p/n is not reflected in Boeing IPC.
  4. d) There is no BAE p/n that equivalent to Boeing improved p/n 10-61833-6.
  5. e) Boeing recommends to upgrades WHCU to the newest Koito p/n 83000-05604 (Boeing p/n 10-61833-6). Boeing drawing provides data allowing this p/n to be installed to B727 airplane. The IPC rev July 2008 will reflect the p/n 83000-05604 usage on 727-200 airplanes.
  6. a) OEM does not track the MTBUR and MTBF of Window heat controller unit p/n 231-2.
  7. b) 231-5 is the latest WHCU p/n produce by Astronics. It is fully interchangeable with p/n 231-2 with an addition of BITE circuits.
  8. c) Suspect the latest mods (Mod L or M depending on the age of the unit) have not been  incorporated for serial number that have failures of parts in the output transistor section (Q26, 27, 28)
  9. d) Astronics has produced 16 SBs related to WHCU p/n 231-2. Refer attachment 7B for modification history from p/n 231-1 to 231-2 mod ‘M’.
  10. e) Astronics only do repair and re-certify origin WHCU p/n 231-x from astronics or all predecessor company names for astronics. 
  11. f) Astronics provide recommendation per below:
  12. Due to cooling air system accumulates dust and dirt which creates thermal stress on the unit, operator is recommended to review the maintenance chk task to inspect the cooling system and cleaning the dust and dirt in E&E compartment to keep dust from clogging the units.
  13. Operator to record mod level for each WHCU installed on the fleet.
  14. Any units had RV1-4 or F1 changed should have Q1 changed as well or there is risk of recurrence of the problem.
  15. b) Since most of the operators has already incorporated new WHCU p/n: 83000-05604, there is no news about p/n 83000-05602 recent few years.
  16. c) P/n 83000-05604 has a BITE function while -05602 has not. The other differences are the weight of unit. -05604 weight is 4.3 kg while -05602 is 3.7 kg.
  17. d) Koito recommended below:
  18. To upgrade p/n 83000-05602 to -05604 (Boeing pn 10-61833-6). Info: p/n 83000-05604 is interchangeable with -05602. P/n 83000-05602 is no longer produce by Koito.
  19. Send repair or overhaul’s WHCU to Koito repair station or Aviation Technical Services, Inc (formerly Goodrich ATS).
  20. All new purchase of Koito WHCU must be obtained from AAxico.
  21. a) No expected MTBUR and no recommended improved part number from repairer.
  22. b) Other operators do not have low time failure (LTF) for window heat controller p/n 231-2.
  23. c) Two units (S/n 478 & 6205) LTF was warranty denied.

2)    Comments from Astronics Advanced Eletronics Systems (previously known as General Dynamics or Olin or Pacific Electro Dynamics)

3)    Comments from Koito Mfg

a)        Design MTBUR for WHCU p/n 83000-05602 is 14046 hrs.

4)    Comments from Aero Technology

1)        S/n 478 was repaired at 1st time visit.  Nil faults found for 2nd shop visit.  

2)        S/n 6205 found internal damaged due to excessive heat on Oct 07. 1 month later the unit was sent for repair and found different circuit board had failed. It appears that the second failure was also caused by an excessive heat.

  1. d) Unable to offer exchange with upgraded p/n due to no stock available.

E) Findings and Discussion.

1)       16 out of 43 WHCU unscheduled removals were caused by overheat. From the study, overheat will affect the window and cause the window to crack. 5 unscheduled removals due to CBs tripped can also cause window to overheat.  

Reason for Removals





Overheat / fail overheat test





Nil heating / inop





Nil control / nil indication / not regulating / not function





CB tripped





Window cracked / arching





Green light intermittent











2)       29 (67.4%) units were sent to Aero Tech for repair, 6 (14%) to Aero Instrument, Avborne 3, High Tech Avionic 1 and Aero Control Avionic and ST Aero 2 each. Most of units were sent to Aero Tech due to low flat rate compare to other vendor.


Aero Tech

Aero Instrument

Aero Control Avionic


ST Aero

High Tech Avionics






















29 (67.4%)

6 (14%)

2 (4.65%)

3 (7%)

2 (4.65%)

1 (2.3%)


3)       Currently there were 57 units installed on the fleet which 47.4% was manufactured by Astronics, 33.3% by BAE system and 17.5% by Koito.

4)       The S/Ns show the repeated removals are 478 (4 removals), M01372 (3 removals), 662, 1607, 1634, 3718, 5126, 6205, 7142 and 7145 (2 removals each s/n).

5)       Most of the WHCU (47.4%) belongs to Astronic. However, Boeing has limited knowledge of the unit and cannot determine the replacement of part 231-2 with 231-5.

6)       All of Astronics p/n 231-2 was not upgraded to latest mod L or M.

7)       Koito unit is the most recommended p/n due to 50% of the unit is in good condition and only one was removed unscheduled for the last 1 year. Furthermore, Boeing only recognizes Koito p/n compared to Astronics or BAEp/n.

8)       BAE p/n 65-52803-8 had shown only 5 units removed unscheduled last year (2007). Compared to Astronics and Koito, BAE WHCU reported fewer problems. However, the OEM (BAE) is NOT contactable. 

F) Recommendations

1)       To advice repairer;  unit found with varistor (RV1-4) or fuse (F1) defect/damaged, transistor Q1 must be replaced to prevent from tripping and overheat shutdown

2)       To evaluate upgrading Koito WHCU p/n 83000-05602 to the newest p/n 83000-05604 (Boeing p/n 10-61833-6)

3)       S/n 7097, to incorporate mod K at next shop visit

4)       S/ns 662, 2749, 3486 and 7142 to incorporate latest mod L or M at next shop visit.

5)       Close monitoring for WHCU s/n: 478, 6205 and M01372 that have low time failure (LTF) last year. Scrapped or exchange for those s/n that have more than 3 LTF within 2 years (until June 2009).

6)       Should spares need to order extra WHCU, always purchase latest version pn: 83000-05604 alt pn: 10-61833-6 from Aaxico (Koito prefer seller).

7)       Inform the maint crew to follow the troubleshooting chart in AMM 30-41-02 figure 101 before make a decision to replace the WHCU due to failure. Ensure that the window temperatures are below 75°F and No. 2 windows are closed and latched before using the troubleshooting chart.

8)       Review maintenance task (‘C’ chk and ‘B’ chk) to inspect the cooling system and cleaning the E&E from dust and dirt.  

G) Conclusions

1)     Operator Window Heat Controller Unit (WHCU) MTBUR is 3838 hrs which is lower than the design MTBUR (14046 hrs).

2)     Aging is the main reason of the unscheduled removals.


Email from Aero Tech dated 22, 29 April, 28 May 2008

Email from Astronics dated 6 and 7 May 2008

Email from Boeing dated 30 April, 9 and 31 May 2008

Email from Koito dated 23 May 2008, 14 and 17 June 2008

Email from Aviation Technical Services dated 24 May 2008

Email from Aaxico dated 26 May 2008

ISAR No. 93-10 dated 30 September 1993

ISAR No. 90-11 dated 12 December 1990

Repainting of Aircraft and Components

The purpose of this process specification is to provide a standard procedure for the repainting of aircraft and components.

This specification describes the requirements and procedures for the repainting of aircraft exterior, interior and components including cowlings, thrust reversers, wheels and brakes etc. The processes apply to primarily for aircraft with notes added for components where necessary.

a. CAA CAIP Part 2 Leaflet 2-7.
b. FAA AC65-15A Chapter 4
c. Airworthiness Notice No. 82.
d. Applicable Boeing Material Specifications.
e. Paint manufacturers’ Instructions, Processes and Standards
f. Component CMM/OHM.
g. Applicable aircraft exterior markings and colour scheme drawings.

Paints and chemicals listed in Appendix A are for reference; and are not exhaustive. Equivalent products may be used based on the specifications where stated since there are many such products in the market. Obtain the product technical data sheet for guidance prior to using it. Consult Technical Services as needed.


a) Carry out all work in adequately ventilated area.

b) Spray paint personnel MUST wear suitable respirators containing filter cartridges for organic vapours when applying epoxy and polyurethane finishes to prevent inhaling spray vapours. Wear rubber gloves, hoods and coveralls so that these materials do not come in contact with exposed skin

c) Where air circulation is insufficient, an air-supplied respirator is required.

d) Observe manufacturer’s safety instructions and precautions at all times.
Avoid prolonged or repeated contact of solvents or conversion coating material with skin. Use gloves, goggles and overalls to prevent contact with stripping material solvents or conversion coating materials.
Note: Do not allow paint stripper to contact skin.

e) Wash body skin or clothing with copious amount of water immediately after contact with any solvent, paint stripper or conversion coating material.

f) Should liquid curing solution or chemicals contacts the skin or eyes, wash skin with soap and water; flush eyes with large amounts of water and seek medical attention immediately.

g) Polyurethane and epoxy coatings are flammable materials, observe fire safety precautions at all times.

h) Ensure aircraft being painted is electrically grounded.


a) Water-Break-Free.
A water-break-free surface is one which maintain a continuous water film for a period of at least 30 seconds after having been sprayed or immersion rinsed in clean water at a temperature below 100ºF (38ºC).

b) A properly cleaned surface is essential to achieve a paint system of a high quality and a long lifetime. When a surface is not cleaned well, problems can occur, include adhesion problems, blisters and pinholes.
– Use clean lint-free cleaning cloths.
– Clean the surface using the “wipe-on-wipe-off” method (use two cloths, one soaked in cleaner to wipe on and the other, a clean, dry cloth to wipe off immediately)
– Do not let the cleaner dry on the substrate.
– Do not touch the degreased surfaces prior to painting (clean the aircraft as the last activity, after masking).
– Thoroughly check the surface for any faults after degreasing.
– Final clean just before painting.

c) Paintshop foreman is to ensure that painting task carried out is adequately defined by technical documents, drawings, data sheets, etc including PS003. Contact Technical Services if information is insufficient.

d) Painter shop foreman is to notify Planning and Maintenance of repainting schedules to plan any structural inspections scheduled including non-destructive inspections that could be better accomplished following paint removal.

e) All painted surface are to be tested/inspected as per para 18.
f) Any stencils/decals can be applied on painted surface after paint adhesion satisfies tape test per para 18.


a) Paints should be mixed, thinned and applied as required in accordance with manufacturers’ data sheets. Do not exceed dry film thickness recommended for best results.

b) Stirring of paints
Where a skin has formed in the paint, it should be removed before stirring. A flat-bladed non-ferrous stirrer should be used.

c) Mixing of paints
Before mixing, check to confirm the right products (base, hardener, and thinner) and that there is enough of each product available to complete the painting procedure. Check data sheet for the correct amount of hardener and thinner to be used.

d) Thinning of paints
The necessary degree of thinning depends on the type of spray equipment
– air pressure
– atmospheric conditions
– kind of paint

The viscosity range or thinning ratio is indicated on the data sheet of each product. Accurate thinning is important for optimum viscosity for best results. Use the correct viscosity cup to check the viscosity as needed.
Note; for tropical conditions, adjust to lower end of viscosity.

e) Straining of paints
All materials should be strained before use. Metal gauze (60 mesh) muslin or three layers of cheese cloth are suitable strainers.

f) Paint must be stored under the right conditions to guarantee the quality. Store the paint in the original unopened containers at a temperature between 5C and 25C. Before using the paint, it must be at the same temperature as the ambient.

g) Paint should be stirred, thinned and strained just before use. The lids of all containers should be wiped clean before opening. Containers should not be left open longer than absolutely necessary, otherwise excessive solvent losses will occur and hardeners may be affected by moisture.


a) Masking is to protect various areas from chemicals e.g. stripper and paint including over-spray. Adequate masking is a must around all openings that could admit paints and chemicals e.g. doors, seams, wheel wells.

b) Use aluminium tape to protect specific areas and seams from paint-stripper.

c) Use masking tape to mask paper (tape is not waterproof).

d) Use cello-tape to line out cheat lines and decorative lines.

e) Use kraft paper to protect large areas from over-spray during painting.

f) Use plastic coated paper or impregnated paper to protect from water and chemicals.

g) Use plastic sheet during stripping and spraying in order to mask bulk areas to avoid overspray but ensure that freshly painted surfaces are fully cured before draping with plastic (polythene). This is to avoid locking in of solvent vapour.

Note: Do not use plastic sheets along the border of area to be painted. This is to avoid dust in the wet paint caused by electrostatic charge of plastic sheets.

Keep the application and mixing equipment clean with solvent cleaner e.g C28/15 to avoid clogging of spray nozzle and depositing of foreign material on the coating surface.

If possible, air used for spray gun operation should be from a separate supply. If taken from a general supply line, install sufficient regulators and manifold to buffer abrupt changes or surges in the air pressure. Install sufficient oil and moisture separators in the air system and blow down the air hose at least twice daily (when in use).


a) If any flight control surface requires repainting LAE should determine if balancing is involved prior to painting. Such surfaces should be removed from the aircraft to allow re-balancing unless SRM permits re-balancing through calculation.

b) Typically flight control surfaces should be stripped of paint chemically (unless fiberglass/graphite/kevlar composite is involved) or mechanically. LAE is to ensure flight control surface is rebalanced per SRM requirement prior to reinstallation per applicable MM after repainting.

c) LAE is to note down the balancing data prior to repainting.

d) LAE is to coordinate with Technical Services to determine the basic weight and corresponding center of gravity position for flight controls as needed. See also Para 19

e) Fibreglass and graphite/kevlar composite surfaces are to be sanded down using grit 400 or finer abrasive paper or very fine Scotch Brite Pads to remove paint coating.

Note: Do not use paint stripper on fiberglass/graphite/kevlar surface or fiberglass repair patches on aluminum skinned composites

This paragraph applies also to repainting of aircraft components.

a. Ensure aircraft is located in a hangar that is relatively dust free. Electrically ground aircraft per applicable Maintenance Manual.

b. For components, ensure that parts are in relatively dust free area.

c. Spot check the adhesion of the paint as necessary with pressure sensitive adhesive tape 3M 600 or equivalent as per para 18. If the paint comes away with the tape, paint removal is recommended – proceed with para 10 or 13 as applicable. Otherwise go to para 9.
Note: Check at sufficient locations to confirm satisfactory adhesion.

d. Use appropriate tools to remove existing sealant and decals on the surface to avoid scribe marks/lines, particularly on aircraft fuselage lap and circumferential joints. Putty knives, razor blades or any sharp tools are prohibited to be used for sealant and decal removal. Refer to SB 737-53A1262 and AWC ref AWC/Boeing737/001(03) dated 6th May 2003


a. Remove any chipped paint around joints and fastener heads. Use aluminum oxide paper grade 280 or finer to feather edges.
Smooth out areas of built-up paint using aluminum oxide paper grade 280 or finer.
Note: Ensure all traces of cleaner are removed by flooding with water and scrubbing with Scotch Brite Pad.

b. Continue scrubbing until a water-break-free surface is attained.


a) When oil stains or other contaminants cannot be removed by the above means, use a clean cloth moistened with MEK or equivalent to wipe affected surface. Wipe area dry immediately with dry clean cloth.

b) Do not apply excessive amount of MEK which will soften the paint film. If a clean water break free surface cannot be obtained, the paint must be stripped as per para 10 or 13.

c. Allow treated area to dry for about two hours. Ensure no water is trapped at joints, seams, opening etc.

d. Mask as required using masking tape and kraft paper or plastic sheet.
Note: Where masking tape was used on areas to be subsequently painted, ensure all traces of tape adhesive are removed. A clean cloth moistened with MEK may be used. Do not allow any MEK to remain on the surface. Immediately wipe off with clean dry cloth.

e. Proceed to Para 14.


Note: Do not use paint stripper to remove paint on composite materials, fiberglass panels and fiberglass repair patches on aluminum skinned composites.
Use only Environmentally Friendly (EA) paint strippers that do not contain phenolics so as to allow easy disposal.

For aircraft this must be carried out meticulously to avoid stripper affecting certain material adversely; and stripper getting into crevices and gaps. For components mask areas that are not to be paint-stripped or where it is not desirable for strippers to be trapped.

a. Cabin and Cockpit Windows including window on Doors
Refer to para 10.2.

b Radome & De-icing Boot
Cover all exposed areas if radome and deicer boots if any are removed.

c Door and Openings
Cover all doors gaps and openings with tapes.

Vertical Fin
Cover exposed areas if rudder is removed. Cover fiberglass/composite panels and access openings.

d Wing & Horizontal Stabilizers
Cover wing-to-fuselage fairings and/or areas covered by these fairings; or cover areas exposed if such fairings are removed. Cover also between fuselage and horizontal stabilizer and fuselage-to-horizontal stabilizer attachment areas.

e Fuselage
Mask all cavities, sealed joints and static and pitot points.

f Landing Gear
Mask landing gear with aluminized kraft paper or plastic sheet and tape.

g Ground Support Equipment
Mask all ground support equipment in close proximity and likely to be affected by paint stripper with double layer aluminized paper and tape.

h Plastic or Fibreglass Structures (Including Composite Material)
Cover these surfaces if not removed from aircraft.

Majority of these windows are made from perspex and will be adversely affected by chemical stripper. Proper masking is therefore critical.

a. Cover all windows surface with aluminized kraft paper or plastic sheet and aluminum tape around the window gaps between fuselage skin and window frame with aluminum tape.

Note: Ensure aluminized kraft paper or plastic sheet is firmly pressed onto the base material by rubbing firmly with a rubber roller over the tape.

b. Cover window with a second layer of larger aluminized kraft paper or plastic sheet and aluminum tape. Ensure that the aluminized kraft paper or plastic sheet overlap is at least 1” over the first layer of aluminum tape before the second layer aluminum tape is applied.

c. Apply third protective screen over all passenger and cockpit windows using curtain of aluminized kraft paper or plastic sheet. This third protective screen is to span lengthwise the fuselage. Overlap where applicable.

Note: Ensure aluminized kraft paper or plastic sheet covers at least two inches above and below the windows.


a. Preparation
Washing is generally not required except for oily or greasy areas; but it is recommended so that all oils are removed to hasten the action of stripper.
Surfaces to be stripped must be dry and the temperature should be between 15 and 35C. Stripping should not be done in hot sun or rain.
The stripper should be thoroughly mixed in its container before use and it is advisable to keep the container closed when not in use. Keep paint strippers away from heat and sun and take care when opening a container (pressure).

b. Equipment for stripping aircraft
Pump: Use a standard 5:1 or 10:1 stainless steel barrel pump with teflon packing.
Use a stainless steel/teflon hose, fitted with a spray gun and swivel, stainless steel spray wand, and a non atomizing tip.
Test assembled equipment to ensure good working order, with no leaks.
Bristle brushes, squeegees, Scotch-Bright pads etc., normally used in stripping operations can be used with paint strippers.

c. Equipment for stripping components
same as (b) above except the pump.


a. Apply a full coat of paint stripper to the surface to be stripped, working from the bottom up and front to back for the fuselage.
If slippage occurs: apply a mist coat of paint stripper to the surface experiencing adhesion problems, let stand 10-15 minutes and re-apply a full coat.

b. Effect of temperature:
EA Paint Strippers are sensitive to temperature. For best results, the ambient temperature, the surface temperature of the aircraft, must be above 20° C, ideally 30° C rises in temperature are preferred. A 10° C rise in temperature will usually halve the stripping time.

c. Dwell time:
Depending on the stripper being used, paint system, film thickness, age of paint system, original surface treatment, temperature; recommended dwell time will vary from one to four hours. Do not agitate the stripper during dwelling. Do not allow the stripper to dry on the surface. Usually the paint will blister when loosened. Some paints do not blister and should be tested for looseness by scraping very gently with wooden or plastic scrapers. The stripper should be removed from the aircraft when it appears to dry or beads of water appear on the surface in large numbers.

a) Complete stripping of primer is not required provided remaining primer adhesion to metal can withstand scratching or pass the adhesion test per Para. 18.

b) If primer removal is required or if primer sticks stubbornly re-apply stripper and agitate such areas with white Scotch Brite Pads.

c) Never use steel wool or a steel brush or steel scrapers as tiny bits of steel will become embedded in the aluminium and this leads to corrosion.

d. Remove as much as possible stripper and loose paint residue using non-metallic scrappers and rags. Thoroughly rinse the reworked area with pressurized water hose and scrub. Use nylon brushes with white Scotch Brite Pads to remove residue.

e. For components, spray application may not be necessary but can also be used. Brush application of stripper can be used as alternative.


a. Agitate a workable area with a stiff polypropylene brush.
b. Squeegee off all loosened paint.
c. If stripping is not complete, re-apply stripper as necessary per para.

d. Hand work with Scotch Brite Pads to remove any residue.
Note: TURCO5948-DPM Cleaner can be used to help lubricate the surface for the Scotch Brite Pads.


a. To remove any remaining paint and/or paint stripper residues, thoroughly wash the entire aircraft or components with a 25% (vol) solution of TURCO 5948-DPM or equivalent, bottom to top, front to back for fuselage.

b. Rinse thoroughly with water, bottom to top and top to bottom, front to back.

c. Inspect bare surfaces for corrosion and other defects.

Note: for components, usually the entire components can be spray rinsed at one go.


a. Chemicals
Prepare the TURCO 5948-DPM solution by mixing 1 part TURCO 5948-DPM with 3 parts potable water (a 25% by volume solution)

b. Equipment
Same as 10.3 b


a. Apply the TURCO 5948-DPM solution from the keel of the aircraft upward to the top of the aircraft in approximately 20 feet long sections. The length of the section should be expanded or shortened based on manpower and equipment available.

b. After the TURCO 5948-DPM is allowed to dwell for a few minutes, use Scotch Brite Pads to thoroughly agitate, bottom to top, front to back for the fuselage, making sure that the entire surface is completely scrubbed.

c. As one section is being agitated, the TURCO 5948-DPM solution should be applied to the next section.

d. Once a section has been agitated, it should be thoroughly rinsed with high pressure, high volume water (warm is better than cold). The rinsing should begin at the bottom of the aircraft section and work up to the top, then back down again, repeating this sequence until all cleaner is rinsed from the surface. Pay particular attention to seams, door opening, etc., that could trap stripper residue.

e. While one section is being rinsed, the next section should be agitated.

f. This process should continue until the entire aircraft fuselage has been thoroughly cleaned and is water break-free.

Note: For components, spray application as above is usually not necessary. Brush apply TURCO 5948-DPM, agitate with white scotchbrite pads as necessary followed by thorough rinsing with water.

This step is optional, and may be omitted for aircraft. It is not necessary for components.

a. Chemicals
Prepare the TURCO METAL-GLO #6 solution by mixing 1 part TURCO METAL GLO #6 with up to 1 part potable water (a 50% by volume solution)

All High strength steel parts or fittings should be masked off with polyethylene sheeting or other water and acid resistant material using water proof tape.

b. Equipment
Same as 10.3 b


a. To help eliminate any tendency to splotch the surface, wet the aircraft surface with water prior to the application of the TURCO METAL GLO #6 etchant. Apply the TURCO METAL GLO #6 solution from the keel line upward to the top of the aircraft in approximately 20 feet long sections. The length of the section should be expanded or compressed depending on manpower and equipment available.

b. After the TURCO METAL GLO #6 has been allowed to dwell for 10-20 minutes, using Scotch Brite Pads, thoroughly agitate, bottom to top, front to back for fuselage, making sure the entire surface is completely scrubbed.

c. As a section has being scrubbed, the TURCO METAL GLO #6 solution should be applied to the next section.

d. Once the first section is agitated, it should be thoroughly rinsed with high pressure, high volume water (warm is better than cold). The rinsing should begin at the bottom of the aircraft section and work up to the top, then down again. Continue this rinsing pattern until the water sheets from the aircraft in a smooth, bubble free film. Pay particular attention to seams, door openings, etc., that could trap etchant residue. It is extremely important to follow this rinsing procedure – bottom to top – to avoid streaking the aircraft.

e. While one section is being rinsed, the next section should be agitated.

f. This procedure should continue in a smoothly flowing operation until the entire aircraft has been thoroughly etched and the aircraft has been thoroughly etched and the aircraft surface is completely water break-free.

LAE is to inspect for corrosion and for damaged sealant. Replace sealant as required. Inspect lap joints for scribe line damage per relevant documents.
Note: Inform Technical Services of any major corrosion findings.

Clean bare aluminum surface with 1:1 MEK/toluene mixture or equivalent, and check for water break-free. It may also be carried out for painted surfaces that have been rubbed down as necessary.


a) Apply chromate conversion coating Alodine 1200 or 1000 per SRM/MM 51 instructions to produce a coating that meets SRM/MM requirements.

b) Ensure water break free surface during rinsing after the alodine treatment.

c) Allow aircraft/component surface to dry. Wipe and blow seams/lap joints dry to help minimize entrapment of moisture and other contaminants in seams and lap joints.

d) Wipe all surfaces with Cleaner C28/15 or other approved solvent cleaner and clean with two rags, one wet/one dry (“wipe on/wipe off” method). Change often to avoid contamination.

e) Tack with tack cloth before primer application. It is now ready for primer application.

f) Remove all contaminated masking from the aircraft and clean the surrounding environment.

Note: The degreased surface should not be touched with bare hands (wear gloves) and should be protected from any contamination before paint application.
If surface has been allowed to collect dust or other contaminants, wipe with MEK or toluene or other suitable cleaning solvent using low lint cloth or rumple cloth.

g) If the time between cleaning and primer application exceeds 12 hours, solvent clean the aircraft/component surface using a blend of MEK and Toluene or other suitable cleaning solvent. Use clean low lint cotton cloth. Cloth should not be dipped into solvent cans as this will contaminate the clean solvent.
Either pour solvent onto the rag or, using an atomizing spray bottle, spray solvent directly onto the surface and wipe dry. Change cloth frequently.


a) Wash surface with an alkaline cleaner mixed as specified by the manufacturer.

b) Sand (rub down) painted surface per 13.1.

c) Sand areas that cannot be chemically stripped (i.e. composite areas); and also during paint rework (i.e. removing runs, orange peel, dust etc) or when the maximum re-coatable time has elapsed.

Note: Before sanding, the surface must be free of grease and other contaminants to avoid grease being sanded into the surface, which will cause bonding problems.


a. Always wear mask, gloves and goggles during sanding.

b. Electrically ground the surface before sanding to avoid frictional (static) electricity.

c. Use the right type of sandpaper for every paint system. The product to be applied determines the sanding grades to be used.

d. Decide on the successive sanding steps for each paint system remembering not to jump any more than 100 points finer at any time. i.e. from P.180 the finest you could go would be P.280 if you wanted to finish with P. 320. This is to avoid sanding marks in the topcoat.

e. When sanding with a sanding machine, avoid mushroom head rivets, seams and tapes or decals. These areas must be treated by hand, preferably using a Scotch Brite pad Type A (or very fine).

f. When sanding old paint systems, sand to the primer to avoid a building-up of too many layers. Too thick paint systems tend to lose their elasticity after a while, which lead to cracking and peeling-off.

g. With wet sanding (optional) the area has to be kept wet with water and sponge. Change the sanding water regularly. After wet sanding rinse the area thoroughly with clean water and dry off.

a. After wet sanding, ensure the surface is dry before painting. Wait at least 14 hours and use compressed air to remove water from seams and rivets (remove dirty kraft paper or plastic sheet and clean the areas before painting) and use tack-rags to remove the dust from the surfaces

After sanding, the areas and surfaces must be cleaned thoroughly to remove the sanding dust. Use compressed air for seams and other parts where dust can settle. Remove dirty kraft paper or plastic sheet and use tackrags on the surface.

a Remove mechanically the oxide film on paint surface all over and “key” the paint surface using aluminum oxide paper grade 280 or finer.

b Clean the surface using white Scotch Brite Pads and water to remove dust and all contaminants.

c Alkaline clean per Para 11 on reworked surfaces and rinse with water. Ensure water-break free surface. Follow para 12 drying and solvent cleaning method prior to paint application.



a) Conventional air spray
Atomizing air pressure: 60 to 70 psi
Pot pressure (if applicable): 5 to 20 psi

b) Air assist air-less electrostatic spray equipment
Fluid pressure: 850 – 1,000 psi
Atomizing air pressure: 65 – 75 psi
Tip size: 0.013 inches (0.33mm) or smaller, preferably .011 inch (0.28mm)

c) High pressure air-assist airless electrostatic spray equipment.
Fluid pressure: 2200 – 2500 psi
Atomizing air pressure: 60 – 75 psi
Tip size: 0.009 – 0.013 inch (0.23 – 0.28mm)

Observe General Notes.
Ensure surface is properly prepared and meets water break free test, fully dried and final tack solvent cleaned prior to painting. Apply one cross coat of primer.
Typical dry film thickness: 0.0005” to 0.0008”

Drying time: Re-coatable 1 hour (typical, see data sheet)
Dry to tape 4 hours. (typical, see data sheet)

After paint has dried check paint adhesion as per para 18.



As per para 14.1


Note: Observe General Notes.
Topcoat must be applied within 48 hours of primer application. If 48 hours is exceeded sanding of primer with scotchbrite pad (white) is necessary.
Apply one cross coat, or two coats of topcoat as required to achieve the desired finish.

Drying Time: Re-coatable 1 hour (typical, see data sheet)
Dry to tape 4 hours (typical, see data sheet)

After paint has dried check paint adhesion as per para 18.

Topcoat must be treated with Aerodur Clearcoat UVR within 4 to 48 hours of topcoat drying if Clearcoat is called out in the drawing.
Apply two cross coats of Aerodur Clearcoat UVR over the topcoat.
Drying Time: Dry to tape 10 to 12 hours.
After paint has dried check paint adhesion as per para 18.


a) In-process defects such as overspray, orange-peel, runs or sags occurring in the primers or in the topcoat which are considered excessive may be reworked by dry sanding with 240 grit or finer abrasive paper followed by wet or dry sanding with 380 – 400 grit or finer abrasive paper. (See para 13)

b) Sanding should not be attempted until the coating being reworked is sufficiently dry to permit sanding. This may take up to 8 hours depending on the weather.

c) After the sanding is completed, the surface has to be cleaned to remove the sanding dust. Use a cloth moistened with solvent cleaner and re-apply primer or topcoat, as required.

d) For some in-process defects such as overspray, runs or sags in finishing coats, it is possible to polish them away. Do not use ammonia-based polishes. Ammonia will destroy the gloss of most aircraft finishes. Only on high-gloss finishes, sags and runs can be removed by wet flatting with 1200 grit wet and dry paper and using clean water and soap. Use a non-ammonia polish with a fine cutting compound to remove the flatting scratches and a final cream polish to revitalize the gloss of the required area.

e) This operation can be done either by hand or polishing machine. When using a machine, a sponge head should be dampened down with water before applying the polish. This decreases the “burning” of painted surface.


Note: Tape adhesion test is to be carried after paint is fully dry. Refer to manufacturer data of specific paints used for “dry to tape” time.

a. Apply 1 inch wide 3M 600 Transparent Film Tape or equivalent to painted surface 1.5 inches long. Repeat this test with fresh tape on at least 3 locations some distances apart.

Note: Shelf life of tapes shall not be more than 6 months old from date of manufacture or as per manufacturer’s shelf life. Storage conditions at 70°F (21°C) and 40-50% relative humidity is recommended.

b. Press tape down firmly (5 pound minimum pressure)

c. Remove the tape within 5 minutes in one abrupt motion perpendicular to the paint surface.

d. Examine area for paint coating failure. Check tape for coating separation.

e. If there is an evidence of paint coating separation, determine extent of defective area and repeat para 8 when necessary.
This must be thoroughly carried out for all large surfaces to be repainted to ensure good paint adhesion. Utmost care is to be exercised not to contaminate areas and tested to be water-break-free.


a Inspect painted surface visually to confirm no defects e.g. orange peel, runs, sags, contamination

b Ensure all mandatory and maintenance markings are re-installed correctly.

c Painter and LAE are to inspect for any damages to transparencies, composites and sealants by solvent and paint removers due to inadequate protection and/or the retention of these products in crevices



Services provided by the Technical Services Department are briefly described here.  The following listing is not meant to be exhaustive. Typically, Technical Services provides the services to

  1. a) Maintenance department and Maintenance Control Centre when
  2. Technical data available does not meet operational requirements;
  3. Defects exceed limitations laid down in manuals;
  4. Necessary spares or tools are not available,
  5. Recurring defects need some investigation/solutions,
  6. Clarifications are needed on technical matters/data,
  7. Modifications are needed to improve economics or to minimise problems,
  8. Projects need technical study or information.
  1. b) Project and Planning department when
  2. Modifications are required to meet airworthiness and/or business requirements;
  3. Technical support when aircraft is in maintenance check at third party,
  4. Technical support for third party aircraft undergoing maintenance,
  5. Engine management including modification requires study/input,
  6. Difficulty is faced in maintenance program; or
  7. Projects need technical study or information.
  1. c) Flight Operations
  2. In issuing, maintaining and controlling aircraft weight and balance reports, load and trim charts,
  3. When technical data/clarifications are needed related to performance issues,
  4. When modifications are required to meet operational requirements,
  5. When projects need technical study or information.
  1. d) Flight Operations and Maintenance departments in
  2. Maintaining aircraft Dispatch Deviation Procedures Guide (DDPG) and Dispatch Procedures Manual (DPM) which incorporate the customized Minimum Equipment List (MEL),
  3. Updating test flight performa,
  4. Vetting test flight results prior submission to local authority,
  5. Analysing flight safety problems.
  6. e) Procurement & Spares when
  7. Parts interchangeability and substitution are desired,
  8. Components need repair instructions, drawings and other advice,
  9. Clarifications needed for technical matters.
  1. f) Flight Operations, Procurement & Spares, Quality Assurance, Project & Planning departments in
  2. Updating Maintenance Schedule,
  3. Managing Technical Publications,
  4. Evaluation and interpretation of Airworthiness Directives, Service Bulletins and other technical matters.
  5. SSUFDR recording readout.
  1. g) All relevant departments in

Managing the Reliability Program including engine trend monitoring, and

Changes in Maintenance Schedule.

  1. h) Other third parties typically in aviation that require technical support and work similar to those described above.


Technical Services shall liaise with Project & Planning and Finance departments to determine the rates to be charged to customers for services rendered.  Typically this will consist of regular services and ad-hoc project type work.  In most cases, charges would be based on manhours spent by Technical Services Engineers.

The Maintenance Dictionary of Terms

The Maintenance Dictionary of Terms

We all know that we have our own language in maintenance. I have written blogs about “hog” pliers, “the angle of the dangle”, etc.  I am sure that we all have our own contributions to the “Maintenance Dictionary”. It is an ever evolving language that will change time and time again as long as there are guys swinging wrenches.

There is one guy at our shop who has coined his fair share of terms that we use here in OAK. I would like to share these terms with you guys and maybe you guys have some terms you would like to add to our Dictionary. Thank you to the mechanic I will call- Non-Sched for your library of terms.

Your Turn in the Barrel                                       It’s your turn to work the broke plane.

Smoking a Turd in Purgatory                               What ever you are doing is going to damn you to hell.

Quick Flip                                                            Working a shift-being off for 8hrs and coming back.

IFE                                                                        In Flight Emergency

Change the Big Part                                              R/Ring the largest, most expensive piece in the system.

Rag Wrench It!                                                      Wiping a leak down and calling it good.                                                                                Derogatory  remark. “All he did was rag wrench it!”

Change the Carburetor                                          Change the MEC or HMU on an engine.

Putting out Fires                                                    Solving all the issues pilots have.

Take it to the Box                                                   Take the plane to the run up hole.

Men Who Stare at Planes                                      Mechanics who don’t work very hard.

Push it to the Pad                                                   Take the plane off line-ground it.

Fielding Gate Calls                                                The process of answering and doing gate calls

Make it go Bye Bye                                               Fix it and get it out of town.

Your on Deck                                                        You are next up for a call.

Is it Taco’d?                                                            Is it messed up beyond repair?

Premium Call                                                         A very easy gate call

Jamalphed                                                              All messed up

Not Enough Bounces                                             Not enough landings

Dolls Eye Indicator                                                 Ball indicator

GSP                                                                         Gravy Sucking Pig

There are more but some are not easily translated into something that would make sense to anyone but a person who was around at the time, like “Swivel Hips”.

All these terms are an amalgamation of years of airline experience, people, and actions. These are terms that are used almost daily here in OAK and will be with me long after my time at SWA is over. Some may think that these types of things don’t mean much but I argue that they do. If you know that it’s “your turn in the barrel” then you may be “changing the big part” because the old one is “taco’d”. When you are done you can “take it to the box” and if your good and not just a “man who stares at planes” then you can “make it go bye bye”. And that’s what we are all about.