{"id":"F2016L01940","name":"AD/PA-25/40 Amdt 9 - Wing Lift Struts","slug":"ad-pa-25-40-amdt-9-wing-lift-struts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":95596,"registerId":"commonwealth-F2016L01940-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Laviasa (Piper) PA-25 (Pawnee) Series Ae","sectionType":"part","heading":"Laviasa (Piper) PA-25 (Pawnee) Series Aeroplanes","content":"# Laviasa (Piper) PA-25 (Pawnee) Series Aeroplanes\n\n| AD/PA-25/40 Amdt 9 | Wing Lift Struts | 26/2016 |\n| ------------------ | ---------------- | ------- |\n\n| Applicability: | Model PA-25, PA-25-235, and PA-25-260 aircraft, serial numbers 25-1 to 25‑8156024. |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement: | Comply with the requirements of FAA AD 2015-08-04, as in force at the date of this AD.Inspections carried out in accordance with previous issues of this AD are considered acceptable for past repetitive inspection requirements of the FAA AD.Note: The FAA AD refers to Piper Mandatory Service Bulletin (MSB) No. 528D dated 19 October 1990 and Piper MSB 910A, dated 10 October 1989. |\n| Compliance: | In accordance with FAA AD 2015-08-04. |\n| | This AD commences on 6 January 2017. |\n| Background: | The manufacturer considers inspection of the lower bottom area of the struts critical.The detection of internal corrosion in struts is in most cases difficult, and may not become apparent until advanced completely through the tube wall. Amendment 3 clarified assessment by a CAR 35 Authorised Person of struts that have corrosion indicated radiographic inspection.Amendment 4 updated the reference document, and allowed new sealed struts as terminating action. The new strut also incorporates a redesigned strut fork.Amendment 5 introduced a reduced corrosion inspection interval following two reports of excessive corrosion appearing within the 5 year interval. The requirement that the wing struts must be removed was also clarified, since service history revealed that water may enter the struts and resulting corrosion may go undetected if the struts are not removed. This has led directly to at least one fatal accident.Amendment 6 corrected the compliance paragraph to allow 24 months since last X-ray inspection.Amendment 7 introduced inspection of the strut upper end if the upper cuff fairing is attached by a screw. Reports were received of severe internal corrosion of wing struts at the upper cuff fairing screw attachment hole area.Amendment 8 aligned this AD with the requirements of a new state of design FAA AD which supersedes AD 93-10-06; which was referenced in Amendment 7 of this AD. |\n| | This Amendment 9 accepts and aligns to the requirements of FAA AD 2015-08-04 now that the USA is not the State of design. CASR Part 39 foreign state-of design requirements may not provide for automatic acceptance of the FAA AD. References to alternative X-Ray inspection have been removed and any AMOC application will be assessed by the CASA. |\n\n![](image.001.png)\n\nBen Wilson \nDelegate of the Civil Aviation Safety Authority\n\n12 December 2016","sortOrder":0},{"sectionNumber":"AD/PA-25/40 Amdt 9","sectionType":"part","heading":"AD/PA-25/40 Amdt 9","content":"## AD/PA-25/40 Amdt 9","sortOrder":1},{"sectionNumber":"Wing Lift Struts","sectionType":"part","heading":"Wing Lift Struts","content":"## Wing Lift Struts","sortOrder":2},{"sectionNumber":"26/2016","sectionType":"part","heading":"26/2016","content":"## 26/2016","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Amendment 9 aligns the AD explicitly to FAA AD 2015-08-04 and removes references to alternative X‑ray inspections; it shifts discretion over alternative methods of compliance (AMOCs) from automatic FAA acceptance to CASA assessment. It also confirms acceptance of previous inspections for past repetitive requirements and sets the AD commencement (6 January 2017), narrowing practical compliance pathways and centralising approval authority with CASA (Background / Requirement / Compliance)."},"complexity_factors":["Incorporation by reference: the AD makes compliance depend on FAA AD 2015-08-04 rather than setting independent technical rules (Requirement/Compliance).","Amendment history: multiple prior amendments (3–8) introduced changes to inspection intervals, terminating actions and inspection scope, creating a layered regulatory record (Background).","Technical inspection methods: reliance on radiographic (X-ray) inspection and removal of alternative X‑ray references increases procedural and equipment complexity (Background / Amendment 9).","Safety-critical uncertainty: internal corrosion is hard to detect and may require strut removal for reliable inspection, raising practical and cost burdens on operators (Background).","Regulatory discretion: removal of automatic foreign‑state acceptance means CASA assesses AMOCs case‑by‑case instead of automatic FAA acceptance (Background / Amendment 9).","Narrow applicability: model- and serial-number-specific scope narrows affected parties but requires careful applicability checks by operators and regulators (Applicability).","Compliance timing and transitional rules: commencement date and acceptance of prior inspections for past repetitive requirements impose record-keeping and retrospective compliance considerations (Compliance / Requirement)."],"plain_english_summary":"This AD requires owners/operators of Laviasa (Piper) PA‑25 series aeroplanes (serials 25‑1 to 25‑8156024) to comply with the inspection and corrective requirements of FAA AD 2015‑08‑04 for wing lift struts, with the AD commencing 6 January 2017. It accepts earlier inspections for past repetitive-inspection requirements.\n\nIt matters because internal corrosion in these struts is difficult to detect and has caused accidents; operators bear the inspection and repair costs, and CASA now assesses any alternative methods of compliance (AMOCs) rather than automatically accepting FAA alternatives."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The legislation has evolved significantly from its original intent. What began as a basic corrosion inspection requirement has expanded through 9 amendments to include: reduced inspection intervals due to new safety data, mandatory strut removal (clarified after a fatal accident), upper strut end inspections for specific fairing types, redesigned strut components as terminating action, and now complex regulatory alignment with foreign state-of-design changes under CASR Part 39. The administrative overhead has increased with removal of automatic alternative inspection methods and requirement for individual CASA assessment of AMOC applications."},"complexity_factors":["Multiple amendment history (9 versions) with cumulative changes to inspection intervals, methods, and scope","Incorporation by reference to foreign legislation (FAA AD 2015-08-04) — requires cross-referencing to US regulations","References to superseded documents (previous FAA AD 93-10-06, earlier amendments) creating a trail of obsolete requirements","Technical aviation terminology (CAR 35 Authorised Person, AMOC, State of design, MSB — Mandatory Service Bulletins)","Conditional logic regarding inspection methods (removal required vs. previous X-ray alternatives now removed)","Specific serial number ranges and model variants creating precise applicability boundaries"],"plain_english_summary":"This CASA Airworthiness Directive forces owners/operators of certain Piper PA-25 Pawnee agricultural aircraft (specific serial range) to remove and inspect wing lift struts for hidden internal corrosion — a corrosion type that’s caused at least one fatal accident by weakening struts from the inside. Compliance follows FAA AD 2015-08-04; alternative inspection methods now require CASA approval. Failure to comply risks catastrophic wing support failure."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-25-40-amdt-9-wing-lift-struts","history":"/api/acts/ad-pa-25-40-amdt-9-wing-lift-struts/history","analysis":"/api/acts/ad-pa-25-40-amdt-9-wing-lift-struts/analysis","conflicts":"/api/acts/ad-pa-25-40-amdt-9-wing-lift-struts/conflicts","importantCases":"/api/acts/ad-pa-25-40-amdt-9-wing-lift-struts/important-cases","documents":"/api/acts/ad-pa-25-40-amdt-9-wing-lift-struts/documents"}}