AD/CF6/14 - High Pressure Turbine Discs (Cth)

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

General Electric Turbine Engines - CF6 Series

AD/CF6/14 High Pressure Turbine Discs 1/91

Applicability: CF6-45/50 series engines.

Requirement: Remove from service, first stage high pressure turbine discs P/N 9264M57P01, 9264M57P02, 1322M88P04, 1322M88P05, 1322M88P07, 9283M31P02, 9283M55P04 and 9283M55P05 in accordance with the compliance schedule of this Directive.

Note: FAA AD 90-19-09 refers.

Compliance: Effective 24 January 1991:

1. Remove within 100 cycles in service (CIS) after the effective date of this AD, discs with greater than or equal to 7,500 CSN.

2. Remove at the next engine shop visit, but no later than 1,000 CIS after the effective date of this AD or prior to accumulating 7,600 CSN, whichever occurs first, discs with greater than or equal to 6,000 CSN, but less than 7,500 CSN.

3. Remove at the next engine shop visit after accumulating 5,500 CSN, but no later than 1,500 CIS after the effective date of this AD or prior to accumulating 7,000 CSN, whichever occurs first, discs with greater than or equal to 4,000 CSN, but less than 6,000 CSN.

4. Remove prior to exceeding 5,500 CSN, discs with less than 4,000 CSN.

5. Thereafter, remove affected discs from service and replace with a serviceable disc prior to exceeding 5,500 CSN.

Note: CF6-50 Series Service Bulletin 72-966, dated September 1, 1989, introduces a new HPT stage one disc, P/N 1473M65P02, which has an FAA approved time limit of 15,000 CSN.

Background: This Directive has been issued to require removal of certain high pressure turbine discs from service. The requirement follows advice of an uncontained stage one high pressure turbine disc fracture event. Investigation of the disc fracture event found six similar discs to be cracked.