Superior Air Parts has responded to the FAA’s recent Notice of Proposed Rulemaking calling for an AD on its crankshafts for the SAP model O-360 and IO-360 piston engines, and certain Lycoming model AEIO-360, IO-360, and O-360 piston engines. The proposed AD would call for removal from service of affected crankshafts.
The FAA initiated the action after examining reports from a series of Superior Air Parts crankshaft assembly failures that occurred on March 6, 2017; August 3, 2017; and October 31, 2018. The failures resulted in the loss of engine power and “immediate or emergency landings,” according to the text of the NPRM. The FAA concluded that all three failures came as the result of fatigue cracking brought about by an “excessive residual white layer forming on the assemblies” that was a byproduct of the manufacturing process.
The FAA is exploring alternatives that are less onerous than the removal of the suspect assemblies from service, including periodic inspections. In a statement provided by SAP, Scott Hayes, VP of sales and marketing, said, “Unfortunately, we were only informed of the proposed rule two weeks ago. Since then, we have been in contact with the FAA regarding their findings to fully understand the issue and identify the most likely cause of the failures. Our engineering team is currently reviewing all of the available information, and once we have determined the actual cause, we can work with the FAA to determine the most logical course of action.”
The proposed AD would affect 115 crankshaft assemblies installed in US-registered aircraft. Hayes added the affected crankshafts had been produced by a certain Superior Air Parts vendor between 2012 and 2014, with the following parts numbers: (P/N) SL36500-A20 or P/N SL36500-A31, with serial numbers 82976-01; 82976-02; SP12-0003 through AP12-0089, inclusive; SP13-0034 through SP13-0150, inclusive; or SP14-0151 through SP14-0202, inclusive.