WASHINGTON—A proposed FAA mandate sheds light on CFM Leap-1A issues plaguing operators in the Middle East and North African environments, identifying dust buildup as the cause of high-pressure turbine rotor blade deterioration and at least two in-service incidents.
The proposed airworthiness directive (AD) is similar to one issued by EASA earlier in 2022, recommending repetitive inspections of Leap-1A engines with at least 800 departures from a specific subset of airports in the Middle East and North Africa (MENA) regions. That directive, based on recommendations made by CFM in December 2021 service bulletins, cited “cracking” of blade and high-pressure turbine (HPT) stage 1 stator nozzles as the unsafe condition, but did not provide details.
The FAA’s proposed AD, also based on the CFM bulletins, confirmed that dust build-up is behind the issue.
“After investigation, the manufacturer determined that engines operating in the MENA region are susceptible to accelerated HPT rotor stage 1 blade deterioration and airfoil distress due to the build-up of dust,” the FAA said. It also said two inflight shutdowns were linked to cracked HPT stage 1 rotor blades caused by the problem.
Both the FAA and EASA directive split affected engines into two groups—Group 1 engines having thrust ratings at 29,000 lb or below, and Group 2 engines with ratings above 29,000. Initial and repetitive check deadlines are shorter for the Group 2 engines.
Like the EASA directive, the FAA’s proposed mandate links the initial checks to the number of departures from MENA airports flagged by CFM. Operators have complained that tracking a subset of cycles involving specific airports is difficult, and have lobbied, without success, for a simplified inspection protocol.
Operators also must report inspection findings to CFM.
“The inspection reports that would be required by this proposed AD will enable the manufacturer to obtain better insight into the nature, cause, and extent of the cracking, and eventually to develop final action to address the unsafe condition,” the FAA said. “Once final action has been identified, the FAA might consider additional rulemaking.”
The public-comment period on the draft rule closes May 5. The FAA mandate does not affect any U.S.-registered aircraft.
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Automating flight logs should make that fairly simple, IMHO. Don't they do that already?