This category contains 104 posts

The 21st Century Model of Certification

I just got off the phone with senior leadership at the FAA and all I can say is “WOW.”

The FAA is talking very seriously about a new model of certification for the aerospace industry focusing on approval of design processes and risk-based oversight in order to better leverage the FAA’s resources to ensure safety of the growing aerospace marketplace.

I shouldn’t be surprised.  The models are there, and they’ve worked.  We’ve sat on Federal Advisory Committees that have made these recommendations to the FAA.  The industry has been talking about this for years.  But sometimes when you talk about projects for too long, you start to lose hope that they will ever come to fruition.

But this idea has the support of the FAA’s senior management and that is what will make the difference.

The new model of certification will likely rely on paradigms like:

  • Safety Management Systems (SMS)
  • A company’s library of FAA-approved or FAA-accepted methods to demonstrate compliance to the regulations
  • FAA Centers of Excellence that can assist with issues that go beyond the approved compliance libraries
  • Self-certification of compliance (following the successful model currently used for issuing TSOA)

Under this new paradigm, a company that specializes in PMAs for landing gear (for example) would have a library of compliance methods – test and procedures that are designed to show compliance to the regulations (including ways to demonstrate true identicality with an existing compliant design).  By following the compliance methods from the library, the company would be able to demonstrate compliance for future landing gear parts.  This would allow the company to more readily develop compliant designs that can be readily PMAed based on the methods that are already known to be sound.

This would involve a major restructuring of how the FAA oversees design approval.  Moving to a TSOA-like self certification should permit small businesses to react very nimbly to market forces and it allows the FAA to more readily focus its resources on real safety issues based on risk assessment.  This paradigm could be supported by FAA Centers of Excellence that would be able top provide support to the design approval community on technical issues.

This paradigm could also impose more responsibility on the design approval applicant.  It would likely be reflected in design systems that would be subject to FAA surveillance.  This would replace the current model in which designs are reviewed.  It would be analogous to the modern approval to production quality systems, in which the FAA approves  system rather than approving each individual part and product that comes out of the system.

For PMA companies, this could help companies bring part to market faster, when those parts fall within the compliance library, because it would limit the FAA’s involvement in projects where compliance can clearly be shown based on known and accepted methods.

We are currently working with the FAA on a presentation (“challenge session“) about this new paradigm; we hope to add this to the program for the 2015 MARPA Conference.

FAA Class on PMAs in Singapore

FAA will conduct a 3-day Parts Manufacturer Approval (PMA), Commercial Parts, and Standard Parts course at the Singapore Aviation Academy, September 28-30, 2015.

The course will be taught by FAA’s expert Robert Sprayberry. The course is a top-level study of the FAA’s approval/acceptance of articles (i.e. PMA process, commercial parts, and standard parts). It will provide instruction on relevant regulations and historical findings as well as include examples and descriptions from industry and FAA perspectives. The class will focus on analysis of relevant advisory circulars and orders.  Additionally this course will provide an overview of the history of the 14 CFR 12.8 and 12.9 for context.

There is still time to register for this course; registration deadline is August 31. For more information contact Diane Migliori @ 202 267-1029 or via email,

ICA Guidance Now Open For Comment!

The FAA has released for comment two guidance documents pertaining to Instructions for Continued Airworthiness (ICA): Draft FAA Order 8110.54B and Draft Advisory Circular 20-ICA. As many readers of the blog know, MARPA has done, and continues to do, a significant amount of work to ensure that ICA are available and accurate in accordance with the Federal Aviation Regulations.

Draft Order 8110.54B is guidance directed at FAA personnel and persons responsible for administering the requirements for ICA.  Among other changes, the draft reorganizes the Order to reflect material moved to AC 20-ICA (below), and importantly incorporates guidance implementing the FAA’s Policy Statement PS-AIR-21.50.01, Type Design Approval Holder Inappropriate Restrictions on the Use and Availability of Instructions for Continued Airworthiness.  MARPA and the PMA industry were closely involved with, and supportive of the FAA in, the adoption that Policy Statement intended to protect the industry from anti-competitive ICA restrictions.

Draft AC 20-ICA is a new Advisory Circular that removes industry-specific guidance from the internal FAA Order and places it in a stand-alone AC.  This effort is similar to the FAA’s actions in revising Order 8110.42D – Parts Manufacturer Approval Procedures and developing the new AC 21.303-4 – Application For Parts Manufacturer Approval Via Tests and Computations Or Identicality.  Like Draft Order 8110.54B, the draft AC implements the FAA policy on ICA established in the Policy Statement.  The proposed AC provides guidance to design approval holders (DAH) and design approval applicants for developing and distributing ICA.

After a preliminary review these documents appear to offer very positive guidance for the PMA and aviation maintenance industries, and appear in line with the policy positions for which MARPA has advocated for many years.  MARPA will be reviewing both of these documents closely and offering comments and support for these policies to the FAA.  We encourage the PMA industry to review both documents as well.

Comments on both guidance documents must be submitted by October 6, 2015, and may be submitted to the FAA via email to  If you have comments or observations that you feel MARPA should include in its comments to the FAA, email them to Ryan Aggergaard at so the we can include them.

MARPA Air Carrier Committee Seeks Clarification on post-AD PMA Parts

The MARPA Air Carrier Committee, led by Michael Rennick, Delta Air Lines Component Engineering Manager, is hard at work supporting PMA users and MARPA members.  In June, members of the MARPA Air Carrier Committee, including Air Wisconsin, American Airlines, Republic Airways, US Airways, Air Canada, and Delta Air Lines, submitted to the FAA a letter seeking clarification on the issue of PMA parts that are alternates to post modification Airworthiness Directive (AD) related parts.

This clarification is necessary because confusion has sometimes arisen between operators and local regulators over the need for an Alternative Method of Compliance (AMoC) for post-modification AD-related PMA parts.  It is the position of the MARPA Air Carrier Committee that if the PMA is an alternate to an OEM part contained in a post-AD configuration, no such AMoC is required.

When a PMA is issued for a replacement part for a post-modification AD-related OEM part, it is uncommon for the PMA applicant to request an AMoC to the AD, or for the FAA to note the AD on the PMA approval.  This makes some sense because a post-AD PMA part is inherently an alternative method of compliance without being described as one. However, an issue arises because many ADs call out only the modified OEM part as a means of compliance.  Because ADs are technically regulations under Part 39, alternate approvals such as PMAs might not satisfy the regulatory requirement and so an AMoC may be required.

It would be beneficial to both operators and PMA manufacturers to see this change.

The OEM part is the source of the condition giving rise to the AD.  The post-modification part must resolve the condition in order to satisfy the AD. During the PMA approval process for the same part, the AD is also taken into consideration..  In order to receive PMA approval, the subject PMA part must resolve the condition resulting in the AD, just as the post-modification OEM part does.  There should be no need to call out an AMoC for the PMA part related to the AD; the underlying condition that necessitated the AD has changed because the approved PMA part has replaced the post-AD OEM part. The PMA should be a valid terminating action for the AD.

There are limited circumstances in which this reasoning may not apply, but these limited circumstances are not the subject upon which the Air Carrier Committee seeks clarification.  For instance an AMoC may be necessary in a scenario in which an AD applies to a higher level component or assembly. In this scenario the PMA replacement for the OEM part may not address the AD for the higher assembly because it is a replacement at the piece-part level, and thus an AMoC may be necessary for the higher assembly.

Generally, however, an AMoC should be inherent in an approved PMA part and therefore unnecessary as a separate approval.  This is the policy clarification that the Air Carrier Committee seeks in the form of a formal FAA communication.  If an approved PMA part is a replacement for a post-AD OEM part, the FAA’s policy should clearly state that the approved PMA is a terminating action for the AD and that no additional approval or discrete AMoC is required. In the alternative, an AMoC could automatically issue for each post-AD PMA to show compliance.

MARPA greatly appreciates the Air Carrier Committee’s work on this project.  MARPA will be working with the FAA and the Committee to determine whether future ADs will list an approved PMA as a valid terminating action, or whether an automatic AMoC should automatically issue with a PMA to show compliance to the AD, or some other solution is desired.  We will keep our members apprised of these developments.

If you are a MARPA member air carrier and want to get involved with the Air Carrier Committee, please email Katt Brigham at  If you are not yet a MARPA member but would like to get involved, visit our membership application page.  MARPA membership is free for air carriers!

Edited to clarify that ADs are regulations and identify possible solutions to the issue raised in the Air Carrier Committee’s letter.

New FAA Draft Policy: Structural Certification Criteria for Antennas, Radomes, and Other External Modifications

The FAA has published new draft guidance for public comment. The policy statement identifies acceptable means of compliance for certification of external modifications to Part 25 aircraft. Such modifications can include antennas, radomes, cameras, and external stores.

The draft policy explains that there has been a significant increase in the number of structural certification projects involving external modifications, especially large antenna installations. It provides guidance on selection of certification requirements within the context of the certification basis of the modification. The directions in the policy statement are each linked to existing regulations, so no new regulatory obligations are meant to be imposed.

Comments are due to the FAA by July 6, 2015.

You can email comments

Comments can also be delivered by mail or hand to:
Federal Aviation Administration
Transport Airplane Directorate
Transport Standards Staff, ANM-110
1601 Lind Avenue SW
Renton, WA 98057

Please send a copy of your comments to MARPA, so that the Trade Association’s response can support your concerns. Please also let the Association know if this is guidance that is important to your business.

New Draft FAA Guidance: replacing vacuum-driven attitude instruments with electronically-driven replacement indicators

The FAA has published new draft guidance for public comment.  The guidance is meant for instruments and indicators designed for small (Part 23 or CAR 3) aircraft.  It is a policy statement that describes acceptable compliance methods for replacing vacuum-driven attitude instruments with electronically-driven replacement indicators. Electronically-driven attitude indicators include indicators that use electrical power to (1) excite an internal gyro, or (2) replace the operation of the gyro with microelectronics.

The policy notes that electronically-driven attitude indicators may replace the existing attitude indicators used in VFR or IFR airplanes.

Comments are due to the FAA by August 21, 2015.

You can email comments to:

Comments can also be delivered by mail or hand to:
Federal Aviation Administration
901 Locust St
Room 301, ACE-114
Kansas City, MO, 64106

Please send a copy of your comments to MARPA, so that the Trade Association’s response can support your concerns.  Please also let the Association know if this is guidance that is important to your business.

FAA Publishes Designee Management Policy for Public Comment – All Manufacturers Need to Review and Comment

Do you rely on a Designated Engineering Representative (DER) to approve data for your business? Do you use DMIRs for issuing 8130-3 tags?  If you do, then you know how critical designees can be to the parts approval process.  Often, though, designees are required by the FAA to do things that the FAA employees themselves are not permitted to do, like require paperwork that is not required by law or regulation (this can be a violation of the Paperwork Reduction Act), or impose standards of conduct that are not required by law or regulation (this can be a violation of the Administrative Procedures Act). When this happens, the designee has no choice but to obey the instructions from the FAA-Advisor … even if they would be illegal if undertaken by the FAA’s employees.

Want to make sure that designees are not used to do things that FAA employees can’t do (by law)?  The be sure to take the time to offer comments to the FAA Designee Management Policy that is now out for comment.  The FAA has issued for public comment a draft change to the guidance document affecting designees.  Although only parts are changed, it is a potential opportunity to comment on the entire document.

The original guidance is called “Order 8000.95, Designee Management Policy.” It was first issued in April of 2014.

This guidance document provides a wide variety of guidance on how to manage FAA designees. It has not and does not appear to cancel FAA Order 8100.8 (Designee Management Handbook), although some of the guidance appears to address some of the same issues as that guidance (failure to cancel 8100.8 might have been an oversight).

As a practical matter, designees (who are the people most directly affected by this guidance) will not be able to write comments that are critical to this guidance. This is because designees can be terminated for cause or without cause, at the discretion of the FAA. So the FAA can terminate a designee for exercising his or her First Amendment freedoms (as long as they come up with any other pretext for the action, including a termination ‘not for cause’). Designees are well aware of this and they regularly self-censor their comments because of the chilling effect that the FAA’s discretionary termination power has had. In some cases, designees have contacted me because they know that I will protect their anonymity.

The real-world issue us that designees rely on their designation from the FAA to ply their trade. If they are terminated (for-cause or not-for-cause) then they cannot simply be a designee for someone else. They need to choose a entirely different career path. So the process for reviewing designee termination is very important. And both the current policy and the draft policy are woefully inadequate, because they offer no standards for review, so the FAA employees are able to rubber stamp any termination decision on review. Honest review depends 100% on the personal integrity of the reviewing personnel – and there is no formal training for the employees who act as reviewers in that process (by comparison, state court judges typically attend judicial training).

The FAA’s failure to have effective standards actually undermines the FAA’s own interests. One example arises in the context of designee termination. The lack of effective standards means that individual FAA employees can cause the termination of a designee for any reason, including a reason that would have been considered to be illegal if it was used to terminate an employee, as long as the party who initiates the termination offers a pretextual reason. There is no formal inquiry into such pretext – it is taken at face value – and the VERY short time period for presenting a defense means that it is tough to be effective in assembling a defense: the full appeal including all supporting evidence must be submitted within 15 days – while the designee is given the charges, he or she has no opportunity to review the FAA’s underlying evidence. In comparison, the appeals panel has 45 days to consider the appeal and then another 15 days to notify the designee of their decision for a total of 60 days. We have seen evidence that FAA inspectors will use this period to gather more evidence to refute the defense and bolster the ‘prosecution’ so clearly the FAA is not bound to any sort of deadline for presenting its own case.

There is plenty that could be improved in the designee management process.

This is a great opportunity to help the FAA to better manage the designee community using effective processes that ensure fairness for everyone. MARPA members should strongly consider reviewing and commenting on this draft guidance.

Comments are dues to the FAA by January 7. Please send comments to MARPA, as well, so we can sure that our comments reflect your concerns.

Comments Due: 01/07/2015
How to Comment: Deliver comments by mail or hand to:
Susan Hill
1625 K Street NW
Suite 300
Washington DC, 20006Email comments to:
Email CommentsFax comments to:
(202) 223-4615, Attn: Susan Hill


My comment on the cancellation of FAA Order 8100.8 failed to take into account FAA Notice 8000.372.  That Notice directs all AIR manufacturing personnel who oversee designees to stop using Order 8100.8 and being using 8000.95 on a schedule.  The schedule reflects the implementation of the Designee Management System (DMS) in those offices.

Under that schedule, all MIDOs with designee management responsibilities should have transitioned to Order 8000.95 during the summer (of 2014).  So Order 8000.95 will have supplanted 8100.8 for MIDOS (but not necessarily for ACOs and FSDOs).  This means that DMIRs and DAR-Fs have transitioned.  But DERs should still be under 8100.8 until they are formally transitioned (at which time they will fall under the instructions of 8000.95).

Special thanks to William Denihan for pointing this out!

Draft Policy Concerning § 33.83 Engine Surveys Due Next Week

We previously wrote in this space about a new Draft Policy Statement issued by the FAA concerning the vibration surveys and engine surveys required under section 33.83 of the Federal Aviation Regulations.  The draft guidance attempts to more narrowly address the FAA’s concerns about full engine test for type certificate applicants.

MARPA plans to provide comments on this Draft Policy Statement to the FAA and has sent a draft of our comments to the MARPA Technical Committee for review.  If any of our members wish to review our draft comments to provide their feedback we would love to hear from you.  Please email Ryan Aggergaard at if there are particular issues in the draft statement you believe should be addressed so that we can incorporate our members’ concerns.

MARPA also encourages our members to file their own comments on the Draft Policy Statement.  Comments are due to the FAA by November 21, 2014.  Comments should be emailed to Dorina Mihail at Comments can also be mailed to her at:

Federal Aviation Administration
Engine and Propeller Directorate
Standards Staff, ANW-111
12 New England Executive Park
Burlington, MA 01803

MARPA looks forward to your comments.

New Guidance: Casting and Proof of Structure

The FAA has released two new advisory circulars that may affect the PMA community.  Both advisory circulars are issued by the Transport Aircraft Directorate and apply to Part 25 aircraft (and parts thereof).

  • Casting Factors, AC 25.621-1: This AC provides guidance for meeting the requirements of 14 C.F.R. 25.621.
    • This regulation imposes limits and restrictions on casting, and also requires a design approval applicant/holder to have control over the operations of a vendor casting facility.
    • The intention of both the regulation and the AC is to drive greater levels of consistency into casting (or to mitigate inconsistencies).
    • Discusses a means of qualifying a casting process


  • Proof of Structure, AC 25.307-1: This AC provides guidance for meeting the requirements of 14 C.F.R. 25.307.
    • This regulation is for the demonstration of compliance for each critical loading condition.
    • The AC provides a list of factors that should be considered in deciding the need for and the extent of testing, including the load levels to be achieved.
    • The AC states that there are four certification approaches to choose from (and provides guidance on each one):
      • Analysis supported by new strength testing of the structure to limit and ultimate load.
      • Analysis validated by previous test evidence and supported with additional limited testing.
      • Analysis supported by previous test evidence.
      • Test only.

We would be interested in hearing from any MARPA member who is affected by one of these new advisory circulars.

FAA Issues Statistical Analysis Guidance – Are You Testing Enough Parts?

The FAA has issued a new advisory circular for statistical analysis.  This AC only applies to engine and APU parts.

The new advisory circular uses statistical analysis to arrive at correct sample sizes.  This sample size formula is introduced for persons who are trying to correlate two populations of parts.  MARPA had pointed out to the FAA that typically a PMA applicant does not correlate two different populations of parts – instead they derive the reasonable tolerances on one population of parts, and then design and produce within those tolerances.  The FAA would like PMA applicants to arrive at their appropriate sample size, test the parts being reverse-engineered, and then produce an equivalent number of pre-PMA parts to test for the same properties (and then correlate the two populations).  This is contrary to current FAA regulatory guidance, which requires the design to be approved and the  requires the production quality system to ensure that parts are all produced within the approved design parameters.  In essence, ACO engineers will now take control of the quality assurance system through the design process.

One of the problems with the AC is that it relied on statistical analysis for clinical trial sample size as the basis for assessing statistical analysis of reverse-engineering sample size.  Clinical trials for pharmaceuticals typically rely on populations of hundreds or even thousands of people.  Trying to test hundreds or thousands of parts in order to reverse-engineer them is simply not realistic.  Furthermore, the degree of part-to-part difference under modern quality assurance systems does not support such large sample sizes.
For those cases where the equations in the advisory circular give a lower number for the appropriate sample size, the FAA has also established minimum sample sizes.  The AC sets some minimum limits for the number of parts that must be tested in order to derive certain values (remember that you need that number of PC parts and also that number of reverse-engineered parts to meet the AC’s requirements):

Minimum Number of Parts to be Sampled

  • For basic material properties that are more dependent on alloy constituency than on part manufacture process – 10 approved parts from three separate lots with at least three parts per lot
  • For properties affected by how the material is processed during part manufacture such as high-cycle fatigue, low-cycle fatigue, creep, tensile strength, crack growth, etc. – 30 approved parts
  • For fatigue testing – at least 25 tested parts that are run until they crack
  • For parts exhibiting complex geometry or complex manufacturing variables, additional specimens may be required
  • For parts considered to have a high degree of criticality, greater sample sizes may be required

No statistical basis is offered for these minimum sample sizes.

The new advisory circular provides guidance for statistical analysis of sample-size despite the fact that no regulation actually requires such a broad-based sample.  The advisory circular appears to potentially change the regulations by increasing the burden on applicants.  To the extent that this is true, it is inappropriate.

Our concern is that despite warnings that this is non-mandatory guidance, this guidance may be used as if it were a regulation, with offices refusing to accept PMA applications that are otherwise valid, but that failed to use this AC as a basis for identifying sample size.

If you find that this AC effectively changes the application obligations imposed on you as a PMA applicant, STC applicant, or other FAA-approval applicant, then please contact MARPA so we can raise this concern with the appropriate personnel at the FAA.

AC 33-10 is known by its full title: Statistical Analysis Considerations for Comparative Test and Analysis Based Compliance Findings for Turbine Engine and Auxiliary Power Unit Replacement, Redesign and Repaired Parts.


Get every new post delivered to your Inbox.

Join 86 other followers