{"id":"F2006B10985","name":"AD/JT8D/29 Amdt 2 - High Pressure Compressor Disc Inspection","slug":"ad-jt8d-29-amdt-2-high-pressure-compressor-disc-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56573,"registerId":"commonwealth-F2006B10985-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT8D/29 Amdt 2 - High Pressure Compressor Disc Inspection","content":"![](image.001.png)\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/JT8D/29 Amdt 1 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nPratt and Whitney Turbine Engines \\- JT8D Series\n\nAD/JT8D/29\n\nAmdt 2\n\n  \nHigh Pressure Compressor Disc Inspection 9/2003\n\nTX\n\nApplicability: Pratt & Whitney JT8D-1,1A,-1B,-7,-7A,-7B,-9,-9A,-11,-15,-15A,-17,-17A,-17R, and\n\n17AR series engines.\n\nRequirement: 1. Carry out initial and repetitive inspections of the high pressure compressor (HPC) discs for corrosion pits and cracks, after stripping the protective coating, in accordance with the accomplishment instructions of Pratt and Whitney (PW) Alert Service Bulletin (ASB) JT8D A6431, Revision 1, dated 7 March, 2003; and\n\n2. Replace HPC discs found with corrosion pits or cracks beyond serviceable limits as defined by PW ASB JT8D A6431, Revision 1, dated 7 March, 2003.\n\nNote 1: FAA AD 2003-12-07 Amdt 39-13192 refers and supersedes FAA AD 98-12-\n\n07 and 94-20-01.\n\nCompliance: For Requirement 1: At intervals specified in the compliance section of PW ASB JT8D A6431, Revision 1, dated 7 March, 2003 from the effective date of this Directive.\n\nFor Requirement 2: Prior to further flight.\n\nNote 2: Whenever the release date of PW ASB JT8D A6431, Revision 1, dated 7 March, 2003 is referred to in the ASB for calculating compliance intervals, the effective date of this AD applies as specified in the compliance for Requirement 1.\n\nThis Amendment becomes effective on 9 July 2003.\n\nPratt and Whitney Turbine Engines \\- JT8D Series\n\nAD/JT8D/29 Amdt 2 (continued)\n\nBackground: This amendment is prompted by operator reports of cracks found on several JT8D steel HPC discs since the existing AD was published which required removal, inspection and recoating of the HPC discs based on utilisation rates. This amendment requires removal and replacement of protective coating on certain HPC discs, initial and repetitive inspections and removal from service as required. The intention of this AD is to prevent fracture of the HPC discs, which could result in uncontained release of engine fragments, in-flight shutdown and airframe damage.\n\nThe original issue of this Airworthiness Directive became effective on 10 September 1998.\n\n![Signature of Jim Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJim Coyne\n\nDelegate of the Civil Aviation Safety Authority 7 July 2003\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 9 July 2003.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Yes. The amendment moves from the original AD's utilisation‑based removal/inspection/recoating regime to mandatory stripping/replacement of protective coating on certain HPC discs, plus explicit initial and repetitive inspections and removal from service where ASB limits are exceeded (Background; Requirement 1–2)."},"complexity_factors":["Requires following an external technical document: PW ASB JT8D A6431 Revision 1 sets procedures and inspection intervals (Requirement 1; Compliance).","Inspections require stripping protective coating and assessing for corrosion pits and cracks to ASB-defined serviceable limits (Requirement 1–2).","Immediate operational consequence if defects found: discs beyond limits must be replaced before further flight (Requirement 2; Compliance).","Applies across multiple JT8D engine variants, increasing affected operator population (Applicability).","Legal framing: issued under CASR subreg 39.1(1) and revokes the prior AD, creating a clear regulatory mandate (preamble).","Compliance timing ties ASB release dates to the AD effective date, creating a synchronization requirement between the AD and the ASB (Note 2; Compliance)."],"plain_english_summary":"This Airworthiness Directive requires operators of Pratt & Whitney JT8D-series engines to strip the protective coating and carry out initial and repetitive inspections of high‑pressure compressor (HPC) discs for corrosion pits and cracks using Pratt & Whitney Alert Service Bulletin JT8D A6431 Revision 1, and to replace any discs that exceed the serviceable limits (replacement required prior to further flight). The CASA delegate issued the AD under CASR 1998; operators pay for inspections and any disc replacements, and must follow the ASB intervals tied to the AD’s effective date."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: preventing high pressure compressor disc failures in JT8D engines. While Amendment 2 expands the inspection requirements (adding repetitive inspections and coating removal/replacement requirements beyond the original utilisation-based approach), this represents an intensification of the same safety measure rather than scope creep into unrelated areas. The core subject matter — HPC disc integrity — has not changed since the original 1998 directive."},"complexity_factors":["Short, single-purpose directive with only 2 substantive requirements","Minimal defined terms (relies on external manufacturer document — PW ASB JT8D A6431 — for technical specifications)","Simple conditional structure: inspect at intervals, replace if damaged","Cross-references only to external FAA directive and manufacturer service bulletin, not to complex legislative provisions","No nested exceptions or elaborate compliance calculations beyond 'effective date' substitution rule in Note 2","Total length: approximately 400 words of operative text"],"plain_english_summary":"CASA requires operators of Pratt & Whitney JT8D-series engines to inspect the high‑pressure compressor disc for corrosion pits and cracks, stripping protective coating for full inspection and grounding any engine with discs beyond safe limits until replaced.  \n\nThe order targets operators of older Boeing 727/737 and DC‑9/MD‑80 types to prevent uncontained engine failures that could eject shrapnel, cause in‑flight shutdowns, and endanger passengers and crew."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt8d-29-amdt-2-high-pressure-compressor-disc-inspection","history":"/api/acts/ad-jt8d-29-amdt-2-high-pressure-compressor-disc-inspection/history","analysis":"/api/acts/ad-jt8d-29-amdt-2-high-pressure-compressor-disc-inspection/analysis","conflicts":"/api/acts/ad-jt8d-29-amdt-2-high-pressure-compressor-disc-inspection/conflicts","importantCases":"/api/acts/ad-jt8d-29-amdt-2-high-pressure-compressor-disc-inspection/important-cases","documents":"/api/acts/ad-jt8d-29-amdt-2-high-pressure-compressor-disc-inspection/documents"}}