Continental Aerospace Technologies has issued a mandatory service bulletin that will be felt by many aircraft customers.
Following on the February 10th Service Bulletin, the US FAA has now issued a further update:
“Mandatory Service Bulletin Released for Crankshaft Counterweights
Update: February 23, 2023
The Federal Aviation Administration (FAA) issued an Airworthiness Directive (AD 2023-04-08) on February 23, 2023, related to the Mandatory Service Bulletin (MSB23-01). Please be aware that AD 2023-04-08 takes precedence over MSB23-01 making the AD the governing document and rule for this issue.
Continental recently identified a potential safety of flight issue for aircraft equipped with Continental 360, 470, 520, 550 series engines and replacement crankshaft assemblies. As the parts manufacturer, Continental reported this to the authorities and released an MSB on February 13, 2023. MSB23-01 pre-emptively advises that an inspection should be performed to confirm that the crankshaft counterweight retaining ring was properly installed in new and rebuilt engines assembled between June 1, 2021, and February 7, 2023. This advice also applies to replacement crankshaft assemblies manufactured between June 1, 2021, through February 7, 2023. To further clarify, the MSB stated that Continental engines with over 200 hours may continue normal flight operations; however, this is no longer valid after the release of the AD. The AD takes precedence over the MSB and now requires an inspection of all affected engines and crankshaft assemblies listed in the MSB.”
The Alabama-based engine manufacturer first issued a mandatory service bulletin on thousands of its late-model engines on February 10, 2023, citing concerns that the snap rings on the crankshaft counterweights on six-cylinder engines, including 360-, 470-, 520- and 550-series engines, might have been improperly seated and could fail at any time. The rings essentially keep the counterweight in place as it helps balance the vibration of the engines, and if one were to fail, the engine could fail catastrophically.
The service bulletin requires aircraft that have been fitted with targeted serial-numbered engines that have fewer than 200 flight hours be flown no more than five additional hours to bring the aircraft into a service centre.
However, Continental says that aircraft that have surpassed the 200 hours “may continue normal flight operations.” This exemption is presumably because engines with that much time on them that have not failed should have the snap rings installed correctly.
The mandatory service bulletin is targeting engines manufactured between 1 June 2021 and 7 February 2023. The inspection requires the removal of at least one cylinder and the use of special tools to determine whether the snap rings are properly seated.
In the meantime, Cirrus Aircraft have grounded all of its aircraft affected by these specific engines. This is likely all of its SR22 aircraft powered by Continental IO-550 and TSIO-550 engines, namely the SR22 and SR22T models.
A statement issued by Cirrus Aircraft reads, “While we are still working with Continental to determine the scope of the issue and specific serial number range of affected aircraft, we are proactively making the decision – out of abundance of caution – to pause all internal Cirrus Aircraft company flight operations on SR22s and SR22Ts manufactured and issued a Certificate of Airworthiness from June 21, 2021, through February 7, 2023.”
The service bulletin also applies to replacement crankshaft assemblies within the same manufacturing dates.
Late model SR20s are Lycoming powered and are thus not affected by the service bulletin. Cirrus became aware of the problem after Continental informed them of the issue.
In a statement from Cirrus, “Cirrus Aircraft continues to operate without restriction all its SR20s, as well as SR22s and SR22Ts manufactured before June 1, 2021, or after February 7, 2023.