1AD/LYC/78 Amdt 5 - Thermostatic Oil Cooler Bypass Valve

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Lycoming Piston Engines

AD/LYC/78

Amdt 5

Thermostatic Oil Cooler Bypass Valve 6/95

Applicability: All Textron Lycoming engines fitted with thermostatic bypass valve P/N 53E19600, 75944, LW-13230 or 53E19980.

Requirement: Carry out a physical inspection of the thermostatic bypass valve in accordance with the procedure detailed in Textron Lycoming Mandatory Service Bulletin No. 518B.

Note: Textron Lycoming Mandatory Service Bulletin No. 518 has been amended to delete reference to a crimp nut dimension.

Compliance: Effective 25 May 1995: Unless previously accomplished in accordance with a previous issue of this Directive;

Dual magneto engines; within 25 hours time in service from 25 May 1995 and thereafter at intervals not to exceed 300 hours time in service.

2. Non dual magneto engines; within 25 hours time in service after 25 May 1995 and thereafter at intervals not to exceed 600 hours time in service.

Background: This Directive requires an inspection of the oil cooler thermostatic bypass valve for security of the crimp nut on the valve shaft. This amendment reflects the release of Textron Lycoming Mandatory Service Bulletin No. 518B. The original issue of MSB 518 included a dimension check of the valve crimp nut in addition to a requirement to inspect the crimp nut for security on the shaft. Following in-service experience, the service bulletin was amended to increase the crimp nut dimension limits. A further amendment of the service bulletin now removes the dimension check entirely.