An airworthiness directive (AD) that affects crankshaft assemblies on Continental Engines has been issued as a final rule. AD-2023-00265-E went into effect Feb. 23. There are differences in assemblies depending on serial number and installation date, so check the AD and service bulletin.

Due to improper installation of the counterweight retaining rings during manufacture, loosening of a counterweight retaining ring may result in the loss of retention of the counterweight. If not addressed, the condition could result in catastrophic engine damage and possible engine seizure. An inspection of the crankshaft is required on affected engines before further flight, or a ferry permit must be obtained to fly the aircraft to a place where the inspection can be performed.

The complete AD may be viewed here.

Differences Between This AD and Related Continental Service Information

Continental’s service information (Continental Mandatory Service Bulletin MSB23–01, Revision A) specifies compliance for engines with less than 200 operating hours, while this AD requires compliance for all affected engines, regardless of the operating hours. The FAA has determined that this unsafe condition, of improperly installed counterweight retaining rings, is likely to exist on affected engines. While the manufacturer’s service information excludes engines accumulating 200 or more operating hours, the FAA has not, as of yet, been provided with adequate data to support that exclusion. In the event the FAA receives data to support the exclusion of engines with more than 200 operating hours or makes other changes to this AD, the FAA may consider further rulemaking.