Attention:
Owners, operators and maintainers of overhauled Teledyne Continental engines.
| File Classification No.: | Z 5000-35 |
|---|---|
| RDIMS No.: | 20765374 |
| Document No.: | CASA 2025-04 |
| Issue No.: | 01 |
| Effective Date: | 2025-04-14 |
Purpose:
The purpose of this Civil Aviation Safety Alert (CASA) is to raise awareness of a reported engine failure of an overhauled Continental IO-520-F engine.
Background:
Transport Canada has been made aware of a quality escape from an engine overhaul facility that affects overhauled Teledyne Continental engines. The crankcase main through bolts and associated nuts were not replaced on a Continental IO-520-F engine at last overhaul. This resulted in insufficient main bearing crush which allowed one of the main bearings to migrate forward. This bearing migration blocked an oil passage causing the failure of a cylinder connecting rod resulting in a catastrophic engine failure. While the affected engine was a Continental IO-520-F, other models may be affected.
Continental Standard Practices Manual, M-0 and Teledyne Continental Aircraft Engines Service Bulletin (SB) 97-6B Mandatory Replacement Parts identify the parts that must be replaced at overhaul. The crankcase through bolts and nuts are listed as mandatory replacement items.
Continental has superseded the through bolts and nuts to improve reliability. The updated through bolt has 2 O-rings on the centre section to prevent external oil leakage. Nuts part numbers (P/N) 634505 and 649496 have been superseded by nut P/N 652541. Nut P/N 634505 and 649496 are a flanged 6-point hex nut while nut P/N 652541 is a flanged 12-point nut requiring a higher torque value. Teledyne Continental Aircraft Engine SB96-7D - Torque Limits identify the torque values for the through bolt nuts.
Recommended action:
Transport Canada recommends that owners, operators, and maintainers of overhauled Teledyne Continental engines affected by Teledyne Continental aircraft Engine SB97-6B Mandatory Replacement Parts review the engine’s technical records to determine if the engine through bolts and associated nuts were replaced at last overhaul. If they weren’t replaced or it could not be determined, then the bolts and nuts should be replaced. Please report any similar findings through the Transport Canada Web Service Difficulty Reporting System (WSDRS).
Approved Maintenance Organizations and engine overhaul facilities maintaining Teledyne Continental engines should ensure that they have access to, and review, both Teledyne Continental Engine SB97-6B Mandatory Replacement Parts and Teledyne Continental Aircraft Engine SB96-7D - Torque Limits when removing or replacing engine through bolts.
Contact office:
For more information concerning this issue, contact a Transport Canada Centre; or contact Kent Goulding, Continuing Airworthiness in Ottawa, by telephone at 1-888-663-3639 by fax at 613-996-9178 or by e-mail at TC.CAWWEBFEEDBACK-retroactionWebMDLN.TC@tc.gc.ca
Original signed by
Jenny Young
Chief, Continuing Airworthiness
National Aircraft Certification
Teledyne Continental engine through bolt replacement
(PDF, 226 KB)
The Transport Canada Civil Aviation Safety Alert (CASA) is used to convey important safety information and contains recommended action items. The CASA strives to assist the aviation industry's efforts to provide a service with the highest possible degree of safety. The information contained herein is often critical and must be conveyed to the appropriate office in a timely manner. The CASA may be changed or amended should new information become available.