Continental Aerospace Technologies has shared details behind a story that Plane & Pilot broke last week. The Mobile, Alabama-engine maker has issued a mandatory service bulletin on thousands of its late-model engines, 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. 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 that planes outfitted with the target serial-numbered engines that have fewer than 200 flight hours be flown no more than five additional hours in order to bring the plane to a service center. For some reason that the company doesn’t explain, planes with more than 200 hours on their target engines “may continue normal flight operations.” This exemption, presumably, is because engines with that much time on them would most likely have failed already if their snap pins were incorrectly installed. Which is a chilling piece of information.
The mandatory service bulletin is targeting engines manufactured between June 1, 2021, and February 7, 2023. It requires operators to get their engines inspected to ensure that the snap rings are properly seated. The inspection requires the removal of at least one cylinder and the use of a special gauge to determine if the rings are properly seated. It won’t be a quick or cheap process.
As we reported last week, in response to Continental’s woes, Cirrus Aircraft grounded all of its company-operated aircraft with affected engines, likely all of its SR22 aircraft which are powered by Continental IO-550 and TSIO-550 series engines; many or most of its company airplanes likely were manufactured within the affected dates. Late-model SR20s are powered by Lycoming engines, which are not affected by the service bulletin.
The issue came to light after Cirrus issued a bulletin to its customers, saying, “We have just been informed by Continental of an issue that affects the engines that power both our SR22 and SR22T. 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 an 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 with the same manufacturing dates.
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