Continental Motors has published “far less onerous and costly” methods for owners of aircraft with Continental IO-520/550 and some IO-470 engines to deal with possibly faulty camshaft gear teeth compared to a controversial procedure the manufacturer put forward in a mandatory service bulletin published in March.
The revision—issued in the form of a critical service bulletin on July 18—is the product of collaborative discussions between Continental, the FAA, and aircraft owner groups, and should “negate any need” for the FAA to publish a future airworthiness directive, said David Oord, AOPA senior director of regulatory affairs.
Aircraft owners with affected engines had been concerned about where the issue was headed since last December, when the FAA issued an airworthiness concern sheet about camshaft gear-teeth failures that were then the subject of a Continental Motors service bulletin.
On March 29, Continental elevated the service bulletin to mandatory, raising the potential of the FAA intervening with an airworthiness directive—as often follows a manufacturer’s action to make a fix mandatory.
In May, AOPA, the American Bonanza Society, Cirrus Owners and Pilots Association, Savvy Aviation, and the Twin Cessna Flyer sent detailed comments to the FAA outlining concerns about the invasive and costly compliance requirements that Continental had advanced.
After the aviation community’s response, Continental Motors announced that it had heard general aviation’s message and would work to amend the mandatory service bulletin.
Oord pointed out that the new service bulletin issued by Continental Motors is labeled critical—no longer mandatory—and includes a replacement procedure option that will not require splitting the engine case, as operators had said would be necessary at great cost in many instances under the superseded mandatory service bulletin.
According to the new document, the inspection intervals and compliance methods are different for those operating under Part 91, who conduct annual aircraft inspections, and those operating under Part 135, who conduct 100-hour inspections.
Continental provided three optional procedures by which owners can replace the camshaft gears in question, in all cases terminating the need for recurring inspections. Owners may opt to replace the gear when the engine case is split for an overhaul or major inspection; or they can replace the gear without splitting an engine with a Permold or Sandcast crankcase.
The document also notes that “subsequent analysis by the FAA has determined that an Airworthiness Directive (AD) may not be warranted at the present time therefore, this bulletin is being reissued as CSB05-8C, a Category 2, Critical Service Bulletin.”
“The result is that the critical service bulletin will be far less onerous and costly for owners,” said Oord, who urged owners with affected engines “to replace the gear at the next engine overhaul.”
“AOPA is confident that the risk of camshaft failure will be properly mitigated through the new service bulletin and replacement of the gear at overhaul,” he said.
Oord expressed AOPA’s appreciation to all the parties involved in this issue for working together to better understand the issue and collaboratively working to resolve it in a way that addresses the concerns of all.
“This is one of those issues which, I believe, was a win for everyone in the end,” he said.