AD/JT8D/29 Amdt 2 - High Pressure Compressor Disc Inspection

Overview

The Airworthiness Directive issued in 2003 under the Civil Aviation Act 1988 aims to address the safety issue of potential cracking and corrosion of high-pressure compressor discs in Pratt and Whitney JT8D series turbine engines. The Civil Aviation Safety Authority (CASA) revoked the previous Airworthiness Directive and introduced an amended directive to ensure the safety of aircraft using these engines. The policy objective of this directive is to prevent engine failure and related hazards by mandating rigorous inspections and replacements of compromised components. This Airworthiness Directive is intended to ensure the continued airworthiness of affected aircraft by requiring operators to conduct initial and repetitive inspections of the high-pressure compressor discs, and to replace any discs that exhibit corrosion pits or cracks beyond serviceable limits, as per the instructions in the Pratt and Whitney Alert Service Bulletin.

Scope and Application

The Airworthiness Directive (AD) AD/JT8D/29 Amdt 2 issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998 applies to Pratt & Whitney JT8D-1,1A,-1B,-7,-7A,-7B,-9,-9A,-11,-15,-15A,-17,-17A,-17R, and 17AR series engines. The AD mandates specific actions to address identified unsafe conditions concerning the high pressure compressor (HPC) discs, which include conducting initial and repetitive inspections for corrosion pits and cracks after removing the protective coating, as well as replacing any HPC discs found to be beyond serviceable limits due to such defects. These requirements are to be followed in accordance with Pratt & Whitney's Alert Service Bulletin (ASB) JT8D A6431, Revision 1, dated 7 March 2003. The AD's geographic reach is national, applying across the Commonwealth of Australia, and it became effective on 9 July 2003. The AD is issued by a delegate of the Civil Aviation Safety Authority (CASA) and is applicable to any entity or individual operating Pratt & Whitney JT8D series engines within Australia. The directive does not specify any exclusions, exemptions, or thresholds, and it supersedes previous ADs related to the same issue.

Key Provisions

The Airworthiness Directive (AD) AD/JT8D/29 Amdt 2, issued by the Civil Aviation Safety Authority (CASA) delegate, pertains to Pratt & Whitney JT8D series turbine engines (section 2). The directive mandates specific actions to address the unsafe condition identified, namely corrosion pits and cracks in the high-pressure compressor (HPC) discs, which could lead to engine failure (section 3). The directive requires operators to conduct initial and repetitive inspections of the HPC discs for corrosion and cracks, following the instructions in Pratt & Whitney’s Alert Service Bulletin (ASB) JT8D A6431, Revision 1, dated 7 March 2003 (section 4). Additionally, any HPC discs found to have corrosion pits or cracks beyond serviceable limits must be replaced before further flight (section 5). Operators of the affected Pratt & Whitney JT8D series engines must comply with the AD by conducting the required inspections at intervals specified in PW ASB JT8D A6431, Revision 1, dated 7 March 2003 (section 6). The inspections must be carried out after removing the protective coating from the HPC discs. Any discs identified with corrosion pits or cracks that exceed the serviceable limits defined by PW ASB JT8D A6431, Revision 1, dated 7 March 2003, must be replaced before the aircraft can fly again (section 7). This directive applies to Pratt & Whitney JT8D-1, 1A, 1B, 7, 7A, 7B, 9, 9A, 11, 15, 15A, 17, 17A, 17R, and 17AR series engines (section 8). Failure to comply with the requirements set out in the AD could result in severe safety risks, including the potential for in-flight shutdown, uncontained engine failure, and airframe damage (section 10). While the AD does not explicitly state penalties, non-compliance could lead to enforcement actions by CASA, including fines, suspension, or revocation of airworthiness certificates, as well as potential civil or criminal liability for any resulting accidents or incidents (section 12). The AD became effective on 9 July 2003, superseding the previous AD AD/JT8D/29 Amdt 1, and was published in the Commonwealth of Australia Gazette on the same date (section 13).