EASA SIB NE-09-08: Compression piston rings with a molybdenum plasma coating.

What to do

Operators should review engine records to identify if affected Airmotive Engineering Corp. cylinder assemblies or piston ring sets installed between January 1, 2003, and December 31, 2006, are present. If increased oil consumption or power loss is observed, perform a differential compression test and inspect cylinders as per TCM overhaul manuals. Follow ECi Service Instructions SI 06-6 and SI 94-4 for additional guidance. No mandatory compliance deadline is specified.

Summary

The FAA Special Airworthiness Information Bulletin SAIB: NE-09-08 is an informational bulletin concerning Teledyne Continental Motors (TCM) 520, 550, and 470 series engines equipped with certain Airmotive Engineering Corp. compression piston rings coated with molybdenum plasma. It addresses a coating delamination issue that can lead to increased oil consumption, reduced cylinder compression, and potential engine power loss. The bulletin clarifies that this issue is not currently considered an unsafe condition requiring mandatory corrective action under 14 CFR part 39.

What changed

This bulletin introduces awareness about a molybdenum plasma coating delamination problem affecting piston rings manufactured between 2003 and 2005 with a C-shaped groove design. It explains that a design change to an L-shaped groove in 2006 has resolved the issue, with no further reports of failures since. The bulletin does not mandate corrective action but provides guidance on inspection and maintenance.

Why it matters

This information is important for operators, maintenance personnel, and repair facilities working with TCM 520, 550, and 470 series engines to identify potential causes of increased oil consumption and power loss. Understanding the piston ring design history helps in diagnosing engine performance issues and ensures proper maintenance and overhaul procedures are followed to maintain engine reliability and safety.