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Mandatory service bulletin raises concernsMandatory service bulletin raises concerns

AOPA has concerns about the recommendations of a mandatory service bulletin issued by Continental Motors for the replacement of certain camshaft gears on many Continental IO-520- and IO-550-series engines, and some Continental IO-470 engines.

Continential Motors issued Mandatory Service Bulletin MSB05-8B on March 29.

AOPA will work with aircraft owners groups and the FAA to explore the areas of concern that the mandatory service bulletin raises, and develop common-sense mitigations that address safety, said David Oord, AOPA senior director of regulatory affairs.

Continental’s mandatory service bulletin calls for replacing the camshaft gear “on all engines currently configured with camshaft gear P/Ns 631845, 655430, 655516, or 656031 within 100-hours of operation, at the next engine overhaul (not to exceed 12 years engine time in service), or whenever the camshaft gear is accessible, whichever occurs first, with camshaft gear P/N 656818.”

Most members face no required action unless the FAA makes the mandatory service bulletin, which was issued March 29, compulsory by issuing an airworthiness directive to enforce it, Oord said.

Camshaft replacement requires splitting the engine’s crankcase, raising concerns about the adverse effects of disassembling an engine when not required for an overhaul or a major repair, Oord said.

He noted that for some aircraft with Pernold-case engines, installing the thicker camshaft also would require modifying the engine case.

AOPA will remain engaged with the FAA to ensure that owners’ concerns are addressed, and will keep members updated about the issue, Oord said.

Topics: Aircraft Regulation

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