Cylinder Cracking Possibly Ongoing in Continental 500-Series Engines, Even Post-AD Actions

On Oct. 25, the FAA issued an Airworthiness Concern Sheet (ACS) regarding a 2020 Airworthiness Directive (AD 2020-16-11) that affects Continental IO-500 series engines. The ACS was prompted by reports that engine cylinders are still cracking despite operators implementing the AD’s corrective actions. The ACS requests feedback from operators about the AD within 30 days.

These engines are primarily Cessna engines but we’re including the story on this website anyway. The following Continental engines are included in the ACS:

GTSIO-520-C, D, H, K, L, M, N; IO-550-G, N, P, R; IOF-550-N, P, R; TSIO-520-BE; TSIO-550-A, B, C, E, G, K, N and TSIOF-550-D, J, K, P with Cylinder heads produced on or after 01 NOV 2014 with serial numbers before AC18KB277

According to the ACS, AD 2020-16-11 required “cylinder head inspection and removal of the casting material build-up on the radius edge of identified cross-flow cylinder heads to reduce the potential for fracture initiation.”

As always, this could ultimately mean another AD or Service Bulletin, or it could wind up meaning little. As the FAA stated in the ACS, “The resolution of this airworthiness concern could involve Airworthiness Directive (AD) action or a Special Airworthiness Information Bulletin (SAIB), or the FAA could determine that no action is needed at this time.”

The FAA is asking for affected operators for the following information:

  • Aircraft type, engine model, and serial numbers of affected cylinders
  • When the AD was completed (Total Hours in Service and date)
  • Which version of the Continental service bulletin was used
  • Whether operators considered the compliance instructions reasonable. If not, why not.
  • Whether rework or re-compliance was needed after complying with the AD
  • Whether cylinders that had AD work done have subsequently cracked, and if so, where on the cylinder the cracking occurred and when it was discovered, along with total hours in service and date when the cracks were discovered.
  • Any other concerns regarding the AD.

The complete service letter is available by clicking here.

The original AD is available by clicking here.

The FAA asked for feedback here:

Boyce Jones
ASE – Aerospace Engineer
Office: Atlanta
ACO Department: Propulsion, AIR-7A2
Street Address: 1701 Columbia Ave City, State, ZIP: Atlanta, GA, 30337
Telephone: (404) 474-5535
Email: [email protected]