Already a member? Please login below for an enhanced experience. Not a member? Join today

Regulatory Brief -- Textron Lycoming piston pin plug wear results in FAA airworthiness actionRegulatory Brief -- Textron Lycoming piston pin plug wear results in FAA airworthiness action

Regulatory Brief

Textron Lycoming piston pin plug wear results in FAA airworthiness action

The issue:

Beginning with engines and cylinder kits shipped in 1994, Textron Lycoming piston pin plugs found on factory new, remanufactured or overhauled engines and cylinder kits have been experiencing an unusually high wear rate. This rate experienced a drastic increase on engines and kits shipped since October 1997. Evidence of excessive wear was discovered between 22 and 700 hours time in service and engine failure was the consequence on two occasions.

The importance to our members:

Thousands of AOPA members have Lycoming engines installed in their aircraft that are either new or have been remanufactured or overhauled by Lycoming during the last five years. Additionally, many more owners have installed the suspect Lycoming cylinder kits over the same time period. Recently, Embry-Riddle Aeronautical University grounded their fleet of new Cessna aircraft with these engines installed due to excessive wear rates and one engine failure prompting FAA to examine the issue more closely. The result could have been the issuance of an AD requiring inspection or replacement of the piston pin plugs.

Significant provisions:

  • Textron Lycoming issued Service Instruction No. 1492A urging careful initial and repetitive inspection of the oil and oil filter for the presence of aluminum or iron residue and flakes that could indicate excessive or premature wear.
  • Textron Lycoming Service Instruction No. 1492A also encourages the use of spectrographic oil analysis to detect aluminum or iron content. This procedure is outlined in Service Letter No. L171.
  • The FAA New England Engine and Propeller Directorate and the FAA New York Aircraft Certification Office have been in regular contact with AOPA seeking service experience data and industry expertise with the piston pin plug wear problem.
  • Initial FAA review of the problem was leading toward the issuance of a potentially sweeping airworthiness directive.

AOPA position:

AOPA agrees with the FAA assessment that excessive piston pin plug wear constitutes a potential significant safety hazard and that owners of the affected engines should be vigilant for signs of premature wear. However, service history data combined with the ability to detect the wear problem at an early stage do not warrant an airworthiness directive calling for tear-down inspection or replacement at this time. This is especially true in view of the fact that the actual cause of the excessive wear is not fully understood and agreed to by the FAA and manufacturer. AOPA strongly encouraged the FAA to issue a Special Airworthiness Information Bulletin (SAIB) to all affected owners in lieu of an airworthiness directive. The SAIB would inform owners about the wear problem and encourage them to carefully check the oil and filter at every oil change for the presence of aluminum or iron. Compliance with an SAIB is not legally mandatory like an AD but in this instance, AOPA strongly encourages owners of affected engines to consider the information being presented by the FAA and follow the procedures outlined in the referenced documents.


After considerable coordination with AOPA and industry, the FAA issued the Special Airworthiness Information Bulletin on April 9, 1999, encouraging affected owners to have their oil and filters inspected carefully at each oil change potentially saving owners thousands of dollars.

Related documents:

FAA Special Airworthiness Information Bulletin ANE-99-18

AOPA News Release 99-2-004