Air

RESPONSE FROM THE FEDERAL AVIATION ADMINISTRATION TO AVIATION SAFETY RECOMMENDATION A04-03

May 25 2005

Chairman Charles Simpson
Transportation Safety Board of Canada
200 Promenade du Portage, PROM
4th Floor Hull, PQ J8X 4B7
Canada

Dear Mr. Simpson:

The Office of Accident Investigation convened a Safety Recommendation Review Board to review the enclosed response to FAA Safety Recommendation 05.010 (A04-03). As a result, the Review Board classified this recommendation as "Closed-Acceptable Action."

If you have any questions, please contact Mr. Jeff Gorney, AAI-210, at
(202) 267-8748.

Sincerely,

[Original letter signed by Frank Del Gandio, Manager, Recommendation and Analysis Division]

Enclosures

cc: ANE-100 (M.J. Bruner)

U.S. Department
of Transportation
Federal Aviation
Administration

This memo is in response to FAA AAI Safety Recommendation 05.010. The subject recommendation asks for an evaluation of the Canadian Transportation Safety Board Safety Recommendation A06/2004 which requested the Federal Aviation Administration (FAA) to publish an Airworthiness Directive (AD) requiring C.3.J software incorporation for the CFM56-5C engine. The software will prevent engine shutdown in the event of an alternator failure.

C.3.J. version software has been incorporated by over 90% of the affected worldwide operators, the remaining CFM56-5C operators are complying voluntarily. The software has been provided to all operators. All other engine models with the same alternator design have similar software logic in place.

The single engine in-flight shut down rate for this alternator bearing failure is .0003 (events per 1,000 flight hours). The CFM56-5C is currently used on four engine airplanes, exclusively.

There has not been an alternator failure due to the identified cause (bearing failure) in over twenty (20) months. In total, there have been twenty-nine (29) alternator failures due to this cause. CFM International is currently pursuing root cause and corrective action for this failure and will report progress to the FAA.

Transport Canada also inquired if the FAA published an issue paper for compliance to FAR 33.28. RTCA/DO-178A and JAA NPA-E-10 (FAA and DGAC joint certification, regulations respectively) were effective at the time of original engine application, to which CFM was in full compliance. FAR 33 Amendment 15, which includes paragraph 33.28 (Electrical and electronic control systems) was not in affect at the time of application (December 15, 1988) for CFM56-5C engine. There would be no record of an issue paper on this subject.

This office has determined that an AD is not necessary due to the absence of an unsafe condition.

[Original memorandum signed by Robert E. Guyotte, for Jay Pardee, Manager, Engine and Propeller Directorate, Aircraft Certification Service]

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