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Regulatory Brief -- Lycoming Crankshaft Retaining Bolt AD ExpandsRegulatory Brief -- Lycoming Crankshaft Retaining Bolt AD Expands

Regulatory Brief

Lycoming Crankshaft Retaining Bolt AD Expands

The issue:

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 importance to our members:

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.


  • AD 2004-05-24 supersedes previously issued AD 2002-23-06
  • Lycoming has identified 161 additional engines by serial number (SN) that they might have assembled with a zinc-plated crankshaft gear retaining bolt, part number (P/N) STD-2209, during the initial assembly or during a subsequent rebuild or overhaul of the engine.

AOPA position:

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.


  • March 15, 2004, FAA publishes AD 2004-05-24
  • August 15, 2003, Lycoming publishes Service Bulletin 554 Supplement 5
  • November 13, 2002 FAA published final AD 2002-23-06
  • November 12, 2002 Lycoming published Service Bulletin SB554 Supplement 3
  • October 1, 2002 FAA published Emergency AD 2002-20-51
  • September 30, 2002, Lycoming published Service Bulletin SB 554

Related documents:

Updated Monday, March 15, 2004 4:12:03 PM