After developing a test facility and running numerous tests, ECi changed its manufacturing process for cylinder assemblies in October 2009. ECI notes that there had been no reported failures on affected assemblies produced after October 2009. “Although ECi’s changes to the manufacturing process may increase the fatigue strength of new production cylinder heads, a large population of potentially discrepant cylinder assemblies remains in service without any required corrective action,” NTSB had stated.
ECi notes the FAA proposal goes even further than the NTSB recommendation to include many more assemblies. “ECi believes that the FAA’s proposed AD is unwarranted, inappropriate, and unnecessarily punitive for the owners of the affected aircraft,” the company says, noting the action was prompted by 30 instances (out of 30,000 installed) of head-to-barrel junction failures in Titan cylinders. None of those resulted in accident or injury, the company adds.
The company further contends that there have been more than 1,200 similar head-to-barrel failures in 520/550 cylinders manufactured by other production approval holders, but FAA has not taken action in those cases.
The Aircraft Owners and Pilots Association also is expressing concern about the proposal, although is still fully reviewing it.
The association questions whether there are other ways to address the agency’s concerns than through the proposed requirements, and quotes Robert Hackman, vice president of regulatory affairs for the association, as saying the proposal “would result in an enormous financial burden for the industry and could have the unintentional result of compromising safety.” AOPA further believes the actual compliance costs to well beyond FAA estimates.
FAA is proposing initial and repetitive inspections, replacement of cracked cylinders and replacement of cylinder assemblies at reduced times-in-service. It would further prohibit installation of the affected assemblies into any engine.
The proposed AD would break the affected cylinders into two groups based on Serial Number (S/N): SN 1-33696 (Group A) and S/N 33697-61176. (Group B). The proposal would require removing Group A cylinder assemblies from service within 25 hr. of the effective date if the operating hours are either fewer than 500 hr. or more than 1,000 hr. Group B cylinder assemblies with 1,000 or more operating hours would need replacement within 25 operating hours following the effective date of the AD.
The proposed AD would require repetitive visual inspections, compression tests and leak checks for cracks on Group A assemblies with between 500-1,000 operating hours and on Group B assemblies with fewer than 1,000 hr.