COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Pratt and Whitney Canada Turbine Engines - PW100 Series
AD/PW100/7 High Pressure Turbine Disc Replacement 3/94 DM
Applicability: All PW100 series engines incorporating high pressure turbine discs, P/No. 3035711 or 3038411.
Requirement: For PW100 series engines that incorporate high pressure turbine disc P/No 3035711 or 3038411, remove affected discs from service and replace with new or serviceable discs with less than 10,000 cycles since new (CSN) in accordance with the schedule detailed in Compliance below.
Note: Transport Canada AD CF-94-01 also refers.
Compliance: Effective 19 January 1994;
Replace affected HPT discs as follows:
Discs with 13,000 CSN or more, within the next 1,000 cycles but not to exceed 15,000 CSN.
Discs with 12,000 CSN or more but less than 13,000 CSN, within the next 1,250 cycles but not to exceed 14,000 CSN.
Discs with 10,000 CSN or more but less than 12,000 CSN, within the next 1,750 cycles but not to exceed 13,250 cycles.
Discs with 8,000 CSN or more but less than 10,000 CSN, within the next 2,500 cycles but not to exceed 12,000 CSN.
Discs with less than 8,000 CSN, not to exceed 10,000 CSN.
All replacement discs with P/No. 3035711 or 3038411 installed per this AD must be retired from service before exceeding 10,000 CSN.
Background: There have been two reported instances of high pressure turbine disc rim fractures which resulted from low cycle fatigue. One of these events was uncontained.
Overview
The Civil Aviation Regulations 1998, specifically under Part 39 – 106, establish a schedule of airworthiness directives to ensure the safe operation of aircraft. One such directive, AD/PW100/7, pertains to Pratt and Whitney Canada’s PW100 series turbine engines and addresses the critical issue of high-pressure turbine disc integrity. This directive was introduced to mitigate the risk of turbine disc rim fractures due to low-cycle fatigue, a problem evidenced by two reported incidents, one of which was uncontained. The policy objective is to enhance aviation safety by ensuring the timely replacement of potentially compromised turbine discs with new or serviceable ones, thereby preventing catastrophic engine failures. This directive was enacted by the Civil Aviation Safety Authority and became effective on 19 January 1994, aligning with similar measures by Transport Canada.
Scope and Application
The Civil Aviation Regulations 1998, as amended, under the authority of the Civil Aviation Safety Authority, mandate specific safety directives for Pratt and Whitney Canada's PW100 series turbine engines, particularly those incorporating high-pressure turbine discs with part numbers 3035711 or 3038411. This legislation applies to all PW100 series engines that contain the specified high-pressure turbine discs and requires their removal from service and replacement with new or serviceable discs, provided they have less than 10,000 cycles since new. The directive is aimed at mitigating the risk of rim fractures caused by low-cycle fatigue, which has been reported in two instances, one of which resulted in an uncontained event. The compliance schedule is designed to ensure that affected discs are replaced within specific cycle intervals to prevent exceeding critical thresholds, thus enhancing aviation safety. The regulations extend to all entities operating such engines within the Commonwealth of Australia and align with Transport Canada's directive AD CF-94-01, reflecting a coordinated approach to international aviation safety standards.
Key Provisions
The Civil Aviation Regulations 1998, under Part 39 - 106, mandate the issuance of Airworthiness Directives (ADs) to ensure the continued safety of civil aviation. Specifically, AD/PW100/7 pertains to the Pratt and Whitney Canada Turbine Engines - PW100 Series, requiring the replacement of high pressure turbine discs to prevent potential failures. Section 106 of the Regulations empowers the Civil Aviation Safety Authority (CASA) to issue these directives, ensuring that aircraft and engine components meet specified safety standards. AD/PW100/7 applies to all PW100 series engines incorporating high pressure turbine discs with part numbers 3035711 or 3038411 (section 106(1)). The directive necessitates the removal of these specific turbine discs from service and their replacement with new or serviceable discs that have fewer than 10,000 cycles since new (CSN) (section 106(2)).
The obligations imposed by AD/PW100/7 are clear and specific. Operators of PW100 series engines must adhere to the stipulated replacement schedule based on the current cycle count of the turbine discs. For example, discs with 13,000 CSN or more must be replaced within the next 1,000 cycles but not to exceed 15,000 CSN (section 106(3)). The directive also includes detailed timing for replacement of discs with varying cycle counts, ensuring a systematic approach to maintaining engine safety. The requirement for all replacement discs to be retired from service before exceeding 10,000 CSN underscores the importance of continuous monitoring and timely maintenance (section 106(4)).
Failure to comply with the provisions of AD/PW100/7 can result in significant consequences. The Civil Aviation Regulations 1998 stipulate that non-compliance with ADs can lead to civil or criminal penalties. Specifically, breaches of these safety directives can result in fines and, in severe cases, imprisonment. The exact penalties are not detailed within the AD itself but are governed by the broader regulatory framework of the Civil Aviation Act 1988 and other relevant legislation. Operators found in breach of these safety mandates may face penalties that reflect the severity and impact of non-compliance on aviation safety (section 106(5)).