The bulletin
Text extracted from the PDF.
SPECIAL
AIRWORTHINESS
INFORMATION
BULLETIN
AIRCRAFT CERTIFICATION SERVICE 800 INDEPENDENCE AVENUE, S.W.
WASHINGTON, DC 20591
U.S. Department of Transportation Federal Aviation Administration
No. ANE-98-24 February 13, 1998
Published by: FAA, AFS-610, P.O. Box 26460, Oklahoma City, OK 73125 This is issued for informational purposes only and any recommendation for corrective action is not mandatory.
Introduction The purpose of the Special Airworthiness Informati on Bulletin is to alert all operators of Lycoming engines, repair stations, mechanics holding In spection Authorizations (IA), and Principal Maintenance Inspectors in the FAA Flight Standard s District Offices (FSDO) of the importance of not reusing the oil pressure screen housing locking star washer on Textron Lycoming engines.
Background On July 6, 1996, an accident occurred on a HU-269- C aircraft belonging to the Tampa Police Department with a Textron Lycoming engine, M odel HIO-360-DIA. Visual examination of the accessory section indicated an external oil leak orig inating at the base of the oil pressure screen housing. Investigation of the nuts and washers revealed that the washer, P/N STD-160, Washer, Internal Locking, 1/4 in., commonly known as “star washers” can be crushed under normal torquing pressures (90 in. lbs.), thereby rendering the lock ing washers ineffective. The lock washers are designed to have a deflected spring action with hardened cutting edges which aids in fastener retention. These spring washer tabs are displ aced under normal torquing pressures and lose their locking capability after first use. In addition, the lo ss of retention after the fi rst use is also aided by high engine temperature cycling.
Recommendations By issuing this Special Airworthiness Info rmation Bulletin, the FAA Engine and Propeller Directorate is alerting all operators of Textr on Lycoming engines, repair stations, mechanics holding Inspection Authorizations (IA), and Princi pal Maintenance Inspectors in the FAA Flight Standards District Offices (FSDO) of the importance of good maintenance practices such as:
• Lock washers should not be reused at overhau l or any time they are removed. AC 65-12A Chapter 10 - Engine Maintenance and Operation (Gen eral Overhaul Procedures), states that all safety devices should be disposed of when they are removed.
For Further Information Contact Rocco Viselli, New York Aircraft Certification Office, FAA, Engine & Propeller Directorate, Valley Stream, New York 11581, telephone (516) 256-7531.