AOPA is objecting to Lycoming's proposal to "retire" more than 5,000 crankshafts, and the association is asking that the FAA not acquiesce to the company's plan.
"To retire more than 5,000 crankshafts as outlined in Lycoming Service Bulletin 569 is unconscionable given that there is no engineering data or clearly defined safety concern to support such action," wrote AOPA's Luis Gutierrez, director of regulatory and certification policy, in comments to the FAA. "AOPA does not believe this action is in accordance with good risk management practices.
"The wholesale replacement of these crankshafts is unwarranted and an unacceptable expense to aircraft owners."
Lycoming recently issued a service bulletin (SB) calling for crankshaft replacement in engines ranging from the O-360 to the IO-720. The company wants all hammer-forged crankshafts "retired" within three years.
While a service bulletin is not mandatory for Part 91 owners who don't use their aircraft in commercial service, SBs frequently become airworthiness directives (ADs), which are, of course, mandatory for everyone. And Lycoming would very much like the FAA to make this SB an AD, at great expense to aircraft owners.
That's why AOPA asked the FAA to first go through the airworthiness concern process and solicit information from mechanics and aircraft owners. After all, even Lycoming admitted that there had been no failures, and nothing to really indicate future failures, among these crankshafts.
And AOPA surveyed its members to determine both the risk and the cost to owners.
"Our survey shows a significant economic impact directly attributed to the SB's requirements," said Gutierrez. "AOPA estimates the total cost to owners at about $32 million."
And that's to fix a "problem" that has yet to be documented. Outside of the crankshafts already covered by ADs, there have been no failures; only the "collective wisdom" of Lycoming and the FAA leads them to think there might be a problem with other hammer-forged crankshafts.
"How does Lycoming or the FAA know with any certainty that this particular group of crankshafts suffers from the same manufacturing defects as those already covered by ADs?" questioned Gutierrez. "Again, there have been no failures, no service difficulty reports."
AOPA argued that the cure might be worse than the disease by tearing down perfectly functional engines long before normal overhaul.
The association offered a reasonable alternative to the Lycoming SB, using a procedure that has worked well in the past.
"AOPA recommends that the FAA work with Lycoming to develop an inspection procedure similar to that used in a previous AD where Lycoming personnel would take a small core sample from the propeller flange to determine if the crankshaft is indeed defective," said Gutierrez. "That worked with the 540-series engines, and it would be much less costly for owners both in terms of dollars and downtime."
April 10, 2006