Sofema Aviation Services (SAS) www.sassofia.com Considers the relationship between Modifications Minor & Major within the EASA Environment.
Lets First Consider the Federal Aviation Administration FAA Background & Criteria
- FARs (Title 14 of the Code of Federal Regulations) define a “major alteration” as “an alteration not listed in the aircraft, aircraft engine, or propeller specifications:
o That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or
o That is not done according to accepted practices or cannot be done by elementary operations.”
o Appendix A to Part 43 of the FARs provides further guidance on what constitutes a major alteration.
Consider Transport Canada Civil Aviation (TCCA) Definition
In Canada, a “major modification” is defined in similar terms in Standard 571 of the Canadian Aviation Regulations (CARs).
Now Consider European Aviation Safety Agency (EASA)
- Under EASA regulations it is, not permitted to modify an aircraft without proper approvals. Even minor modifications for example seat covers, replacement of stickers, or the installation of a magazine holder requires appropriate approved maintenance data.
- With the European Union EASA mandates all Mods for Commercial Air Transport ( CAT) & Large Aircraft – Minor or Major (STC) are managed through an EASA Part 21 Design Organisation Process.
Major / Minor Considerations
- EASA Determination of Major/Minor (when it is confirmed that it is outside the scope of CS-STAN) is determined by the flow-chart to be found in 21A.91.
- According to the FAA Federal Aviation Regulations (FAR’s) an alteration other than a major alteration is considered minor.
- An FAA MINOR change may be considered as equivalent to CS-STAN. An STC is a Major change to type design (not a Major Alteration) and has the same meaning and approval process both in the EU and US.
- In both the U.S. and Canada, minor alterations require only “acceptable data,” which can include drawings and methods recommended by the manufacturer, or relevant advisory circulars.
- A major alteration requires “approved data,” which is essentially technical data that has been approved by the regulatory authority.
o May include data associated with a type certificate or supplemental Type Certificate (STC).
o Note That within the FAA system, there are alternative sources of approved data:
· Technical standard order authorizations,
· Parts manufacturer approvals,
· Airworthiness directives, and
· Maintenance instructions approved by an FAA designated engineering representative (DER).
- FAA Determination Major / Minor
o It is the installer’s responsibility to determine whether an installation is minor or major. (with FAA oversight)
- EASA Determination Major / Minor
o Must be performed by EASA Approved Design Organisation.
FAA Form 337
The person who performs or supervises a major repair or major alteration must prepare FAA Form 337. The form is executed at least in duplicate and is used to record major repairs and major alterations made to an aircraft, airframe, powerplant, propeller, appliance, or a component part thereof.
FAA Form 337 is used to record major alterations as well as field approvals not requiring an STC.
- Note 1 – Major alterations made with an STC also require Form 337.
- Note 2 – If an alteration introduces a major change in type design, it requires a type certificate (TC) amendment or an STC.
Does EASA accept FAA Form 337?
EASA accepts alterations on non-critical components that are substantiated via Form 337, as detailed in the EASA-FAA Technical Implementation Procedure (TIP) rev 5, paragraph 3.2.8.2 EASA Acceptance of FAA Alteration Data:
- “Except for alterations on critical components, FAA-approved or accepted alterations per 14 CFR Part 43 installed on a used aircraft exported from the U.S., regardless of the State of Design of the aircraft, are considered approved by EASA at the time of import to the European Union. EASA shall accept such FAA alteration data when substantiated via an appropriately executed FAA Form 8110-3, FAA Form 8100-9, FAA Form 337 or logbook entry.
Note 1 – Alterations on critical components must be EASA-approved via STC, in accordance with TIP paragraph 2.2 (Design Approval Procedures for Supplemental Type Certificates (STCs)).
Note 2 – An FAA STC whose installation is documented on Form 337 must be approved by EASA in accordance with TIP paragraph 2.2.”
Note 3 – Form 337 should not be used for minor alterations.
EASA Supplemental Type Certificates (STC)
Modifications requiring an STC are also designed by a Part 21 DOA. However, an STC needs to be separately approved by EASA itself.
As part of the Bi-Lateral Obligations, EASA manages a full list of all approved STCs (available on the website).
The STC becomes a significant part of the aircraft’s compliance with design requirements and may affect a Flight Manual change (supplement).
Approved Part 21 Design Organization Modifications
A Part 21 Design Organization (often referred to as DOA – Design Organization Approval) is able to develop modifications and issue appropriate airworthiness documentation. Often provided in the form of Service Bulletins.
The Part 21 Organisation is responsible for Instructions for Continued Airworthiness (ICA) detailing maintenance requirements which form part of the operators approved maintenance program (AMP).
Next Steps
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Tags:
aviation, Code of Federal Regulations, Design Organisation Approval (DOA), EASA, European Aviation Safety Agency (EASA), FAA, FAA Federal Aviation Regulations, FAA Form 337, Part 21, SAS blogs, Supplemental Type Certificates (STC), Transport Canada Civil Aviation (TCCA)
