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MARPA Sues! Engine Vibration Rule Change was Illegal, says the PMA Trade Association.

Today, MARPA began a lawsuit against the U.S. government over the change to the vibration rule – a rule change that was illegally promulgated, and that affects PMA applicants.

MARPA filed a Notice of Appeal with the U.S. Circuit Court of Appeals of the District of Columbia Circuit appealing the “Vibration Rule Change.”  This rule change removes component test as a means of satisfying the engine survey requirement of 14 C.F.R. § 33.83, and requires PMA applicants to perform engine testing.

MARPA had previously announced that this rule was a problem.

Procedural Problems with the Rule

The FAA made the change to the rules concerning vibration testing (14 C.F.R. § 33.83) in the July 5th Federal Register on page 39623.

No prior “notice and comment” was offered and the change was immediately effective. This violates the Administrative Procedures Act, which requires prior notice and comment, and it also violates FAA regulations, which do not permit a direct final rule without comment period under these circumstances.

For your easy reference, the rule change can be found online at

The new rule was labeled as a non-substantive technical amendment; however non its face it is clear that this was a substantive change that should have been open to prior public comment.  Had it been open to public comment, then MARPA and others would have commented that it undermines the existing regulatory system, rather than improving it, and that it imposes unnecessary burdens on both the applicant and the government with no commensurate safety benefit.

MARPA Attempts to Have the Rule Withdrawn

MARPA request that this rule be withdrawn, citing a number of facts that supported withdrawal:

  1. this was a substantive rule change,
  2. this rule change was issued without opportunity for comment,
  3. industry would have opposed this change if it had been permitted to provide notice and comment,
  4. the manner of promulgation violated both FAA regulations and the Administrative Procedures Act, and
  5. even for direct final rules, the FAA is required to withdraw such rules if it receives a negative comment during the comment period.

We filed a formal request for withdrawal with the FAA on August 3, 2012.  The rule was not withdrawn before the end of the 60 day appeal period arrived (September 3) so MARPA filed a notice of appeal on the last day that such a notice could be filed (today).

Why Does This Matter?

Section 33.83 requires an engine survey as part of the vibration showing.  The old rule stated:

“The engine surveys shall be based upon an appropriate combination of experience, analysis, and component test and shall address, as a minimum, blades, vanes, rotor discs, spacers, and rotor shafts.”

Under the old rule, it is clear that component testing, combined with experience and/or analysis was a means of performing the engine survey.  The new rule changed this language to this:

Compliance with this section must be demonstrated by engine test, and must address, as a minimum, blades, vanes, rotor discs, spacers, and rotor shafts. The conduct of the engine test should be based on an appropriate combination of experience, analysis, and component test.

The new rule makes it clear that an engine survey requires an engine test, and that experience, analysis, and component test are merely elements that influence the engine test.  The question that certainly must arise in a PMA applicant’s head is, does the change (the introduction of the term “engine test”) mean that a PMA applicant has to perform an engine test?  Or can applicants continue to rely on component testing and comparative anaysis (where appropriate)?

While many people (including PMA applicants) would like to be able to interpret the new language to mean that component test is still a viable approach, the preamble to the rule clarifies the intent of the change.  In describing the rule change, the preamble states:

The clarification is in response to inquiries from applicants requesting FAA engine type certifications and aftermarket certifications, such as supplemental type certificates, parts manufacturing approvals, and repairs. We are revising the regulations to clarify that ‘‘engine surveys’’ require an engine test.

* * *

The requested clarification was whether an ‘‘appropriate combination of experience, analysis, and component test’’ is acceptable in lieu of an engine test. We are revising § 33.83(a) to clarify that the applicants must conduct the engine surveys by the means of an engine test, and that the applicants may use an “appropriate combination of experience, analysis, and component test” in support of conducting the engine test. [emphasis added]

This language makes it clear that component test (with experience and/or analysis), alone, is not enough to meet the language of the regulations. This preambulatory language clarifies that the FAA expects the applicant to perform an engine test, and that a component test, with analysis and/or experience (but without a full engine test) is not sufficient..

This change could increase the cost of engine PMAs to a level that makes them economically unattainable.


About Jason Dickstein

Mr. Dickstein is the President of the Washington Aviation Group, a Washington, DC-based aviation law firm. He represents several aviation trade associations, including the Aviation Suppliers Association, the Aircraft Electronics Association, the Air Carrier Purchasing Conference, and the Modification and Replacement Parts Association. He also represents private clients drawn from the spectrum of the aviation industry.



  1. Pingback: Vibration Rule – Still In the Works? | MARPA - August 1, 2013

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