{"id":"F2008L04128","name":"AD/PA-25/43 - Exhaust System and Related Areas - Inspection","slug":"ad-pa-25-43-exhaust-system-and-related-areas-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":76052,"registerId":"commonwealth-F2008L04128-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Piper PA-25 (Pawnee) Series Aeroplanes","sectionType":"division","heading":"Piper PA-25 (Pawnee) Series Aeroplanes","content":"### Piper PA-25 (Pawnee) Series Aeroplanes\n\n| AD/PA-25/43 | Exhaust System and Related Areas - Inspection | 12/2008 |\n| ----------- | --------------------------------------------- | ------- |\n\n| Applicability: | Piper PA-25-235 with serial numbers from 25-2000 to 25-4171 inclusive, except aircraft fitted with muffler and exhaust stack clamps included in muffler installation kit, Piper Part Number 753-753. |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | Inspect the entire exhaust system for signs of cracks, burn-throughs, weld separations, failed internal baffles etc. The muffler need not be removed from the aircraft provided visual inspection with a probe light and mirror are made through the muffler tail pipe outlet and one end of the muffler stack connection.This inspection must be performed in accordance with either USA AD 67-14-07 or Piper Service Bulletin No. 241A. |\n| Compliance: | At each scheduled inspection for issue of a maintenance release following the date of effectivity of this Airworthiness Directive. |\n| | This Airworthiness Directive becomes effective on 20 November 2008. |\n| Background: | The original issue of AD/PA-25/12 in 1962 applied to all models of PA-25 and specified inspection of the exhaust system in accordance with Piper Service Letter No. 324B.The original issue of AD/PA-25/26 in 1968 also specified inspection of the exhaust system in accordance with Piper Service Bulletin No. 241 and USA AD 67-14-07, and was applicable to PA-25-235 serial numbers 25-2000 to 25-4171. It was accompanied by amendment of AD/PA-25/12 to exclude PA-25-235 with serial numbers given above.AD/PA-25/26 was cancelled in 1974 and PA-25-235 with serial numbers given above were restored to AD/PA-25/12. This action was taken because SB No. 241 and AD 67-14-07 do not require periodic inspection of the exhaust system after installation of Piper muffler and exhaust stack clamps included in muffler installation kit, Piper Part Number 753-753. The service history of the PA-25 in Australia at the time suggested that periodic inspection of the exhaust system was unavoidable, and SL No. 324B and C provided a suitable inspection regime. |\n\n| | AD/PA-25/12 Amdt 2 has been reviewed. Mandatory application of SL No. 324C to PA-25 is unique to Australia. The service history of the exhaust system in PA-25 in Australia has improved and indicates that use of an AD to mandate SL No. 324C is no longer warranted. AD/PA-25/12 is to be cancelled.This AD is the same as AD/PA-25/26 prior to cancellation, and mandates the periodic inspection specified in USA AD 67-14-07 and Piper SB No. 241A. |\n| --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png) \nCharles Lenarcic \nDelegate of the Civil Aviation Safety Authority\n\n9 October 2008","sortOrder":0},{"sectionNumber":"AD/PA-25/43","sectionType":"part","heading":"AD/PA-25/43","content":"## AD/PA-25/43","sortOrder":1},{"sectionNumber":"Exhaust System and Related Areas - Inspe","sectionType":"part","heading":"Exhaust System and Related Areas - Inspection","content":"## Exhaust System and Related Areas - Inspection","sortOrder":2},{"sectionNumber":"12/2008","sectionType":"part","heading":"12/2008","content":"## 12/2008","sortOrder":3}],"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":4,"scope_assessment":{"changed":true,"description":"This AD restores mandatory periodic exhaust inspections for PA‑25‑235 serials 25‑2000 to 25‑4171 (except aircraft with muffler kit P/N 753‑753), aligning Australian requirements with USA AD 67‑14‑07 and Piper SB No. 241A rather than the previously mandated Australian Service Letter SL No. 324C. Mechanically, it reintroduces a recurring inspection obligation for the listed fleet, shifting recurring compliance costs and inspection scheduling onto owners/operators and requiring reference to the external AD and service bulletin for inspection details (Applicability; Requirement; Background; Compliance)."},"complexity_factors":["Applicability limited to a specific serial‑number range and an explicit exception for aircraft fitted with muffler/exhaust stack clamps in kit P/N 753‑753 (Applicability; Background).","Direct cross‑reference to external regulatory and manufacturer documents — USA AD 67‑14‑07 and Piper Service Bulletin No. 241A — which must be consulted to complete the inspection requirements (Requirement).","Prescribed inspection method allows visual inspection through the muffler tail pipe with probe light and mirror without removing the muffler, constraining acceptable techniques while reducing labour (Requirement).","Compliance timing is tied to each scheduled inspection for issue of a maintenance release, creating a recurring, operator‑borne compliance cost and scheduling obligation (Compliance).","Regulatory history and amendments (cancellation and restoration of prior ADs, and removal of a uniquely Australian mandatory service letter) add interpretive complexity about scope and precedence (Background).","Limited technical discretion for inspectors because specific defect types are listed (cracks, burn‑throughs, weld separations, failed baffles), increasing the need for documented findings at each maintenance release (Requirement).","Effective date and enforcement are specified, so operators must align maintenance planning from 20 November 2008 (Compliance)."],"plain_english_summary":"This Airworthiness Directive requires owners/operators of Piper PA-25-235 aircraft (serials 25‑2000 to 25‑4171), except those fitted with muffler kit Piper Part Number 753‑753, to inspect the entire exhaust system for cracks, burn‑throughs, weld separations, failed internal baffles and similar defects. Inspections must follow USA AD 67‑14‑07 or Piper Service Bulletin No. 241A and be carried out at each scheduled maintenance release."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD represents a return to the original scope of AD/PA-25/26 (1968) after a 34-year deviation. The scope has not expanded beyond its original purpose of mandating exhaust inspections for specific PA-25-235 serial numbers. Rather, it narrows the regulatory approach by cancelling the uniquely Australian requirement (SL No. 324C) and reverting to the internationally harmonised standard. The scope remains tightly focused on exhaust system safety for a specific aircraft type and serial range."},"complexity_factors":["Multiple historical ADs referenced and explained (AD/PA-25/12, AD/PA-25/26) with their amendment and cancellation history","Specific serial number range applicability with an exception clause (excluding aircraft with Piper Part Number 753-753)","Cross-reference to foreign legislation (USA AD 67-14-07) and manufacturer documents (Piper Service Bulletin No. 241A, Service Letter No. 324B/C)","Conditional inspection method (muffler need not be removed IF visual inspection performed via probe light and mirror)","Nested effective date logic (compliance tied to 'date of effectivity' and subsequent scheduled inspections)"],"plain_english_summary":"This AD reinstates mandatory exhaust-system inspections for Piper PA-25 Pawnee aircraft (serials 25‑2000 to 25‑4171) that have not had the specified muffler upgrade kit fitted. At every scheduled maintenance after 20 Nov 2008, mechanics must inspect for cracks, holes, broken welds or internal damage using a flashlight and mirror through the tailpipe (no muffler removal), following US AD 67‑14‑07 or Piper Service Bulletin 241A.\n\nIt replaces a uniquely Australian extra requirement and aligns oversight with the long‑standing US guidance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-25-43-exhaust-system-and-related-areas-inspection","history":"/api/acts/ad-pa-25-43-exhaust-system-and-related-areas-inspection/history","analysis":"/api/acts/ad-pa-25-43-exhaust-system-and-related-areas-inspection/analysis","conflicts":"/api/acts/ad-pa-25-43-exhaust-system-and-related-areas-inspection/conflicts","importantCases":"/api/acts/ad-pa-25-43-exhaust-system-and-related-areas-inspection/important-cases","documents":"/api/acts/ad-pa-25-43-exhaust-system-and-related-areas-inspection/documents"}}