On October 13, 2002, FAA published Final AD 2002-23-06 requiring replacement of defective Lycoming crankshaft gear retaining bolts. The new AD supersedes Emergency AD 2002-20-51 issued in early October 2002.
UPDATE: March 15, 2004, FAA publishes AD 2004-05-24 superseding AD 2002-23-06. This new AD adds 161 additional impacted engines by serial number.
The AD, applicable to engines installed in several models of Cessna and Piper airplanes, Aero Commander, Commander 114, Lake Renegade, Mooney M20M, various Maule airplanes, and several others, applies various turbocharged and normally aspirate 540 series Lycoming engines. This AD marks the fifth instance FAA has taken mandatory airworthiness against Lycoming 540-series engines over the past several months. Some owners that replaced defective crankshaft retaining bolts under the previously issued emergency AD may have to once again remove and replace the bolt.
AOPA agrees that, in this particular situation, the possibility of crankshaft gear retaining bolt failure and possible subsequent engine failure warrant airworthiness action. However, AOPA is displeased that Lycoming and FAA's failure to properly identify the population of defective bolts has resulted in multiple ADs and may possibly result in some aircraft owners once again replacing a bolt just installed to meet the requirements of the previously issued Emergency AD.