AOPA Comments on Proposed AD May Merit Explanation of why FAA Exceeded NTSB Recommendations

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ARTICLE: Cylinder-removal AD would increase costs, decrease safety


The FAA has issued a proposed Airworthiness Directive for certain Airmotive Engineering Corp. replacement parts manufacturer approval (PMA) cylinder assemblies marketed by Engine Components International Division (ECi), used on the Continental Motors, Inc.. The agency action would “require initial and repetitive inspections, replacement of cracked cylinders, and replacement of cylinder assemblies at reduced times-in-service.” That is a heavy remedial agenda, but it is based on “failure reports of multiple cylinder head-to-barrel separations and cracked and leaking aluminum cylinder heads.”

In response to the draft amendment to 14 CFR Part 39, AOPA stated:

“This proposed AD would result in an enormous financial burden for the industry, and could have the unintentional result of compromising safety. Requiring the replacement of many cylinders, in addition to repetitive inspections, goes well beyond the recommendations of a National Transportation Safety Board Safety Recommendation issued in February 2012.”

Rules proposed by the FAA must meet a Benefit/Cost analysis, but the mere fact that the replacement of the cracked PMA cylinders or the repeated inspection of the engine is costly does not preclude the issuance of the final rule.

AOPA’s statement also points to the fact that the FAA AD exceeds what the NTSB recommended, to wit:

Require repetitive inspection of Engine Components, Inc. cylinder assemblies produced between May 2003 and October 2009 (serial numbers 7709 through 52884) installed on Teledyne Continental Motors model 520 and 550 engines and removal of these cylinder assemblies once they reach the engine manufacturer’s recommended normal time (hours) in service between overhauls. (A-12-7)

The AD does make further gradations among the serialized cylinders and assigns shorter inspection periods for the two classes. The FAA proposal cites discussions with the PMA company and the NTSB as well as analysis of the data provided to them.

The Federal Register notice does not explain why it adopted restrictions other than those offered by the NTSB. That variance, though not mandated, would appear to merit some final discussion in the next (perhaps not final) iteration of the AD.

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