EASA AD US-2023-05-16: Engine - Crankshaft Counterweight Retaining Rings - Inspection

What to do

Operators of affected Continental reciprocating engines must inspect the crankshaft assembly for correct installation of the counterweight retaining rings as specified in Continental Mandatory Service Bulletin MSB23-01, Revision A. If improper installation is detected, corrective actions must be taken promptly. This AD is effective March 15, 2023, and comments must be submitted by May 1, 2023.

Summary

Airworthiness Directive 2023-05-16 is a final rule issued by the FAA addressing Continental Aerospace Technologies, Inc. reciprocating engines, including models such as GTSIO-520 series, IO-360 series, IO-470 series, IO-520 series, IO-550 series, LTSIO-360 series, O-470 series, TSIO-360 series, TSIO-520 series, TSIO-550 series, TSIOF-550-K, and TSIOL-550 series. This directive mandates inspection of the crankshaft assembly for proper installation of the counterweight retaining rings in the counterweight groove and requires corrective actions if improper installation is found.

What changed

This AD supersedes AD 2023-04-08 by expanding the applicability to include additional engine models such as IO-470-A, -C, -F, -LO; TSIO-360-F; and TSIO-360-FB. It also revises the special flight permit provisions by removing the limitation regarding metal contamination in the oil filter. The directive incorporates feedback from public comments and clarifies inspection requirements.

Why it matters

Proper installation of counterweight retaining rings is critical to prevent loosening and potential departure of counterweights, which can cause loss of engine oil pressure, catastrophic engine damage, engine seizure, and possible loss of aircraft. Compliance ensures continued airworthiness and safety of affected Continental reciprocating engines, protecting operators and maintenance personnel from in-flight engine failures and costly repairs.