COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Allison Turbine Engines - 250 Series
AD/AL 250/65 Engine Power and Accessory Gearbox - New
Magnetic Plug Introduction
4/85
Applicability: Model 250-C30 and C30S engines (and power and accessory gearboxes) installed in or intended for installation in S-76 Helicopters and which incorporate magnetic plug P/N 23001915.
Requirement: Fit new magnetic plugs P/N 6871534 in lieu of old plugs P/N 23001915.
Allison 250-C30, C30S CEB-A-72-3098 Revision 1.
Compliance: 1. For installed Engine/gearbox assemblies:
Unless already accomplished, prior to issue of the next Maintenance Release after 30 April 1985.
2. For uninstalled engines, power and accessory gearboxes, housings and covers: Prior to installation in an aircraft.
Background: In service experience with automatic fuzz burn off magnetic plugs P/N 23001915 has indicated that early detection of oil system contamination is being lost due to the effectiveness of the fuzz burn off feature.
CEB-A-72-3098 replaces the auto fuzz burn off plug with the 6871534 plug which is currently fitted to the 250-C20 engine and has proven to be reliable in providing an early indication of engine or gearbox oil contamination.