{"id":"F2006B05572","name":"AD/PA-25/36 Amdt 3 - Fuselage Wing Spar Attachment Fittings","slug":"ad-pa-25-36-amdt-3-fuselage-wing-spar-attachment-fittings","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46579,"registerId":"commonwealth-F2006B05572-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-25/36 Amdt 3 - Fuselage Wing Spar Attachment Fittings","content":"![](image.001.png)  \nPiper PA-25 (Pawnee) Series Aeroplanes\n\nAD/PA-25/36\n\nAmdt 3\n\n  \nFuselage Wing Spar Attachment Fittings 11/99\n\nApplicability: PA-25 (PA-25-150 & PA-25-180), PA-25-235 and PA-25-260 aeroplanes all serial numbers.\n\nRequirement: 1. Gain access to the forward wing spar to fuselage and aft wing spar to fuselage attachment fittings. Remove any cracked, flaking or bubbling paint and any chemical build up.\n\nPerform a close detailed visual inspection of the front and rear fuselage tubular cluster wing attach fittings. Inspect for cracks, corrosion and general condition. Pay particular attention to the areas indicated in Figure 1.\n\n    2. Remove the wings from the aircraft. Thoroughly clean the forward wing spar fuselage attachment fitting. Carry out the following inspections:\n\n    (a) Visually inspect the forward fitting for corrosion and general condition. The bore of the lugs of the fitting should be particularly examined for evidence of corrosion occurring between the lug laminates.\n\n    (b) Perform a Magnetic Particle inspection of the forward fittings for cracks in accordance with CAO 108.8 using the magnetic flow technique. Pay particular attention to the areas indicated in Figure 1. Replace any cracked fittings.\n\nNote 1: FAA AD 95-12-01 and FAA AD 93-21-12 refers.\n\nNote 2: In assessing serviceability of a fitting after corrosion removal, consideration should be made of the possibility of corrosion between the laminates. In a number of cracked fittings provided to the Authority, interlaminate corrosion has been significant, even though it was not apparent in the bore of the fitting.\n\nNote 3: Numerous proposals for repair by welding of cracked fittings have been received by CASA, the FAA and the manufacturer. Because of difficulties ensuring complete crack removal and alteration of the strength and fatigue properties of the fitting by welding, repair is not viable, and cracked fittings must be replaced.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.002.png)\n\nCompliance: 1. Inspect in accordance with Requirement 1 of this Directive within 100 hrs time in service or 900 landings whichever occurs first after 4 January 1996.\n\nRe-inspect at intervals not exceeding 100 hours time in service or 900 landings, whichever occurs first.\n\n2. Initially inspect in accordance with Requirement 2 of this Directive within 2000 hrs time in service of forward fitting installation or within 100 hrs time in service after 4 January 1996, whichever occurs last;\n\nRe-inspect at intervals not exceeding 500 hrs time in service or 4500 landings, whichever occurs first.\n\nIf the forward fitting has been modified in accordance with Gippsland Aeronautics CASA STC 83-8 (Modification GA96-01) or Kosola & Associates Inc FAA STC SA00992AT, then the requirement to carry out Requirement 2 is removed.\n\nHowever, incorporation of either STC makes the fitting subject to the inspection, maintenance and fatigue limitations in the relevant STC instructions. Further, as the Gippsland Aeronautics fitting is common to the Gippsland Aeronautics GA- 200, any Airworthiness Directives issued against the GA-200 relating to the wing fitting will be applicable to this STC.\n\nAny fitting found cracked is to be replaced before further flight.\n\nNote 4: The Authority is aware of a number of instances where the wing bolts have been overtightened upon wing reinstallation. This combined with poor tolerances between the wing lugs and the fittings can cause the fitting lugs to bend and crack. The need to comply with the appropriate wing installation instructions is emphasised.\n\nThis Amendment becomes effective on 4 November 1999.\n\nBackground: Two failures of a wing front spar fuselage attachment have been reported. In both cases the wing separated from the aeroplane. Since issue of this Directive, numerous cracked and corroded fittings have been reported.\n\nAmendment 2 extended the interval for inspection with wings removed, and required a magnetic particle inspection in lieu of the previous fluorescent penetrant inspection. The magnetic particle inspection has been demonstrated to be considerably more effective than dye penetrant methods.\n\nAmendment 3 clarifies the inspection requirements and addresses the amended FAA AD. Further, it includes reference to two approved STCs that relieve the Magnetic Particle Inspection.\n\nAmendment 2 of this Directive became effective on 4 January 1996\\. Amendment 1 of this Directive became effective on 25 May 1995.\n\nThe original issue of this Directive became effective in September 1977.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"The instrument has been amended over time. Amendment 2 changed inspection intervals and replaced dye-penetrant inspection with Magnetic Particle Inspection (Background). Amendment 3 clarified inspection requirements, addressed an amended FAA AD, and added two approved STCs that relieve the Requirement 2 MPI obligation for modified forward fittings (Background; Compliance: 2). These amendments alter how operators meet the inspection obligations (timing, method and possibility of STC-based exemption) compared with the original Directive."},"complexity_factors":["Multiple inspection modalities (close visual inspections and Magnetic Particle Inspection) with different scopes (Requirement 1 vs Requirement 2).","Different compliance intervals for each inspection level and for initial vs repeat inspections (Compliance: 1 and Compliance: 2).","Requirement 2 may require wing removal, increasing logistical complexity and downtime (Requirement 2).","Exception pathway via two specific STCs that remove Requirement 2 but impose STC-specific maintenance/fatigue limits (Compliance: 2).","Prohibition on welding as a repair method (Note 3) forces part replacement and affects supply/repair decisions.","Technical specificity (MPI per CAO 108.8 magnetic flow technique) requires trained personnel and equipment (Requirement 2(b); Background).","Safety-critical outcome (wing separation reported) increases enforcement and replacement urgency (Background; Compliance)."],"plain_english_summary":"### What this instrument does (mechanics)\n\n- Applies to all Piper PA-25 series aeroplanes listed (PA-25-150, PA-25-180, PA-25-235 and PA-25-260; all serial numbers) (Applicability). \n\n- Requires operators/maintainers to inspect the fuselage wing-spar attachment fittings for cracks, corrosion and general condition and to remove and replace any cracked fittings before further flight. The inspections are split into two levels:\n  - Requirement 1: Gain access to the forward and aft wing-spar-to-fuselage fittings, remove flaking paint/chemical build-up and perform close, detailed visual inspections of the front and rear tubular cluster wing attach fittings, paying particular attention to areas shown in Figure 1 (Requirement 1).\n  - Requirement 2: With the wings removed, thoroughly clean the forward wing-spar fuselage attachment fitting, visually check for corrosion (with special attention to corrosion between lug laminates) and perform a Magnetic Particle Inspection (MPI) for cracks using the magnetic flow technique in accordance with CAO 108.8. Replace any cracked fittings (Requirement 2(a)–(b)).\n\n- Prohibits repair of cracked fittings by welding: cracked fittings must be replaced because welding cannot reliably remove cracks or preserve original strength/fatigue properties (Note 3).\n\n- Sets firm compliance intervals for initial and repeat inspections. For Requirement 1 inspections: within 100 hours time-in-service or 900 landings after 4 January 1996, then re-inspect at intervals not exceeding 100 hours or 900 landings (Compliance: 1). For Requirement 2 (with wings removed): initial inspect within 2000 hours time-in-service of forward fitting installation or within 100 hours after 4 January 1996 (whichever is later); re-inspect at intervals not exceeding 500 hours or 4500 landings (Compliance: 2).\n\n- Provides an exception to Requirement 2 if the forward fitting has been modified under one of two approved Supplemental Type Certificates (STCs). If modified under Gippsland Aeronautics CASA STC 83-8 (Modification GA96-01) or Kosola & Associates Inc FAA STC SA00992AT, the MPI/Requirement 2 is not required; however, the modified fitting becomes subject to the inspection, maintenance and fatigue limits in the relevant STC (Compliance: 2).\n\n- Emphasises correct wing reinstallation procedures because overtightening and poor tolerances can bend and crack fitting lugs (Note 4).\n\n- Any cracked fitting found must be replaced before further flight (Compliance: general; Requirement 2(b)).\n\n\n### Why the rule exists (official rationale and what the source says)\n\n- The Background states two reported failures of the front wing-spar fuselage attachment that resulted in wing separation, and since the Directive was issued numerous cracked and corroded fittings have been reported. The AD was amended to improve inspection effectiveness (Background).\n\n- The instrument notes that Amendment 2 extended certain inspection intervals and replaced dye-penetrant testing with Magnetic Particle Inspection because MPI is demonstrated to be more effective (Background). Amendment 3 clarifies inspection requirements, addresses an amended FAA AD and adds the two STC references that remove the MPI requirement for modified fittings (Background).\n\n\n### Who pays and who decides\n\n- Aircraft owners/operators and their maintenance organisations pay the direct costs: labour to access fittings, clean and inspect, remove wings where required, perform MPI (a specialised NDT task), and purchase and fit replacement fittings where cracks/corrosion are found (Requirement 1; Requirement 2; Compliance).\n\n- Civil Aviation Safety Authority (CASA) imposes the Directive and sets intervals and acceptable methods; approval of STCs is a mechanism that alters the inspection obligation for fitted aeroplanes (Compliance: 2; Background).\n\n\n### Incentives, trade-offs and implementation risks (practical effects)\n\n- Compliance imposes recurring direct maintenance costs and aircraft downtime because:\n  - Requirement 2 may require wing removal and specialised MPI at stated intervals (Requirement 2; Compliance: 2). \n  - Replacement of cracked fittings requires parts and fitment time; repair by welding is not permitted (Note 3).\n\n- The STC route is an explicit substitution: operators who incorporate one of the two approved STCs avoid the Requirement 2 MPI, but then must follow the STC-specific inspection/maintenance/fatigue limits. This shifts costs and inspection patterns for modified aircraft and concentrates decision power in the hands of STC holders and approvers (Compliance: 2).\n\n- Behavioural risks identified in the instrument: overtightening bolts during wing reinstallation and poor lug-fitting tolerances can cause bending and cracking of fitting lugs. The Directive emphasises correct wing installation instructions to mitigate this (Note 4).\n\n- Technical execution risk: MPI is required because it detects cracks that dye-penetrant methods missed; MPI requires trained technicians and appropriate equipment (Requirement 2(b); Background). Failure to perform the specified technique risks undetected cracks.\n\n\n### Effects on private enterprise, competition and choice\n\n- Maintenance providers experienced increased demand for MPI-capable non-destructive testing and part replacement work; smaller maintenance operators without MPI capability may face lost work or must subcontract (Requirement 2(b)).\n\n- Operators face a choice: continue with recurring MPI and wing removals under this AD, or install an approved STC (if eligible) and follow the STC's inspection/fatigue regime. The STC path may change long-run maintenance costs and aircraft availability (Compliance: 2).\n\n- Because welding repairs are disallowed (Note 3), parts replacement is the available remedial option; that affects part suppliers and inventory decisions.\n\n\n### Concrete compliance obligations (who does what and when)\n\n- Aircraft owners/operators must:\n  - Perform Requirement 1 visual inspections within 100 hours or 900 landings after 4 Jan 1996 and repeat at those intervals (Compliance: 1).\n  - Perform Requirement 2 inspections (wings off + MPI) within the stated initial threshold (2000 hours since forward fitting installation or 100 hours after 4 Jan 1996, whichever is later) and repeat at intervals not exceeding 500 hours or 4500 landings (Compliance: 2).\n  - Replace any cracked fittings before further flight (Requirement 2(b); Compliance).\n  - Follow correct wing reinstallation instructions to avoid inducing cracks (Note 4).\n\n- If the forward fitting is modified under the specified STCs, Requirement 2 (MPI with wings removed) is not required; instead comply with the STC’s instructions (Compliance: 2).\n\n\n### Implementation burdens and opportunity costs\n\n- Direct maintenance expense, specialised NDT labour/equipment, aircraft downtime (wing removal), and replacement parts (Requirement 1; Requirement 2; Note 3).\n- Choosing an STC incurs modification cost and shifts the aircraft into the STC’s inspection/fatigue regime (Compliance: 2).\n\n\n### Source citations\n\nAll statements above are grounded in the Directive text: Applicability; Requirement 1; Requirement 2(a)–(b); Notes 1–4; Compliance paragraphs; Background; and Amendment history contained in the instrument."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The directive has evolved significantly from its original 1977 issue. What began as a basic corrosion and crack inspection has expanded to include: (1) mandatory magnetic particle inspection replacing less effective dye penetrant methods (Amendment 2); (2) recognition of approved modification pathways via STCs that relieve certain inspection burdens (Amendment 3); and (3) explicit prohibition of welding repairs following industry pressure. The compliance framework has also become more nuanced, moving from simple hourly intervals to dual-trigger systems (hours OR landings) and conditional relief mechanisms. The scope has effectively shifted from 'inspect and repair' to 'inspect with advanced methods, replace only, or modify via approved alternative'."},"complexity_factors":["Multiple inspection tiers with different methods (visual vs magnetic particle) and access requirements (wings on vs wings off)","Dual compliance metrics (flight hours OR landings, whichever comes first) with different thresholds for initial vs recurring inspections","Conditional logic for STC modifications that remove certain requirements but impose alternative compliance obligations","Cross-references to external documents: CAO 108.8 (inspection standards), two FAA ADs (95-12-01 and 93-21-12), and two STCs (Gippsland Aeronautics CASA STC 83-8 and Kosola FAA STC SA00992AT)","Amendment history tracking (original 1977, Amendments 1-3) with varying effective dates and requirement changes","Technical aviation terminology requiring specialised knowledge (magnetic flow technique, interlaminate corrosion, lug laminates, STC)"],"plain_english_summary":"This is a **safety directive for specific Piper Pawnee aircraft** used mainly in agricultural operations (crop dusting, aerial work). It mandates **mandatory inspections of critical wing attachment points** where the wings bolt to the fuselage.\n\n**What it does:**\n- Requires owners/operators to inspect the wing spar attachment fittings for **cracks, corrosion, and general deterioration**\n- Mandates two levels of inspection:\n  - **Visual inspection** of the tubular cluster fittings (looking for cracked paint, bubbling, corrosion)\n  - **Magnetic Particle Inspection** (a specialised crack-detection method using magnetic fields and iron particles) of the forward fittings after wing removal\n- **Prohibits welding repairs** — cracked fittings must be replaced entirely\n- Sets **strict time limits**: inspections every 100 flight hours or 900 landings for visual checks; every 500 hours or 4,500 landings for detailed magnetic inspections\n\n**Who it affects:**\n- Owners and operators of **Piper PA-25 series aircraft** (models 150, 180, 235, and 260 horsepower variants)\n- All serial numbers are covered — no exceptions\n\n**Why it matters:**\nTwo aircraft have already suffered **complete wing separation in flight** due to fitting failures. The directive prevents catastrophic structural failure by catching fatigue cracks and corrosion before they cause the wing to detach. The rules are non-negotiable — cracked fittings must be replaced before the aircraft flies again.\n\n**Key relief:** If owners install approved modified fittings (via specific Supplemental Type Certificates from Gippsland Aeronautics or Kosola & Associates), they can skip the magnetic particle inspection requirement — but must follow the modified component's own maintenance rules instead."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-25-36-amdt-3-fuselage-wing-spar-attachment-fittings","history":"/api/acts/ad-pa-25-36-amdt-3-fuselage-wing-spar-attachment-fittings/history","analysis":"/api/acts/ad-pa-25-36-amdt-3-fuselage-wing-spar-attachment-fittings/analysis","conflicts":"/api/acts/ad-pa-25-36-amdt-3-fuselage-wing-spar-attachment-fittings/conflicts","importantCases":"/api/acts/ad-pa-25-36-amdt-3-fuselage-wing-spar-attachment-fittings/important-cases","documents":"/api/acts/ad-pa-25-36-amdt-3-fuselage-wing-spar-attachment-fittings/documents"}}