Lycoming Mandatory Service Bulletin No. 632


Lycoming issued a mandatory service bulletin Identification of Connecting Rods with Non-Conforming Small End Bushings today that affects approximately 1300 engines, ranging from O-235 to IO-720 models:

Models affected: All Lycoming engines
Time of compliance: Within the next 10 hours of engine operation.

For engines still under warranty, the manufacturer has authorized specific parts and labor allowances. See the service bulletin for details.

Required Action

  1. Identify and isolate/segregate affected engines and engines with suspect connecting rod assemblies or connecting rod bushings:
    A. Refer to the engine serial numbers in Table 1 and identify affected engines in your fleet.
    B. Contact your Lycoming parts source to review your parts invoice shipment dates as well as maintenance and engine logbooks to identify any engine in your fleet that could have one or more suspect connecting rod bushings (identified in Table 2) or connecting rod assemblies (identified in Table 2).
  2. As you complete the remaining “Required Action” steps, complete the online survey at
  3. Complete the “Connecting Rod Inspection” in this Service Bulletin on all affected engines in Table 1 and on any engine which could have suspect connecting rods or connecting rod bushings (Table 2).
  4. Review your spares inventory records and physical inventory of all connecting rod bushings and connecting rod assemblies for part numbers and ship dates in Table 2:
    A. Remove and quarantine all suspect connecting rod bushings and connecting rod assemblies identified in Table 2 from your spares inventory.
    Arrange for the return of all suspect connecting rod assemblies and connecting rod bushings (identified in Table 2) through the Lycoming Distributor from which they were originally procured in exchange for conforming replacement parts.
  5. If applicable, file a warranty claim per the “Limited Warranty” in this Service Bulletin


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