{"id":"F2006B10039","name":"AD/G1159/36 - Corrosion and Cracking Fuselage Station 452","slug":"ad-g1159-36-corrosion-and-cracking-fuselage-station-452","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55454,"registerId":"commonwealth-F2006B10039-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/G1159/36 - Corrosion and Cracking Fuselage Station 452","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nGulfstream (Grumman) G1159 and G-IV Series Aeroplanes\n\nAD/G1159/36 Corrosion and Cracking Fuselage Station 452 9/90\n\nApplicability: Serial numbers:\n\n001, 002, 003, 005, 006, 007, 008, 010, 011, 012, 013, 014, 015, 017, 018, 019, 020,\n\n021, 022, 023, 024, 025, 026, 027, 028, 029, 031, 033, 034, 035, 037, 038, 039, 040,\n\n041, 043, 044, 045, 046, 047, 049, 050, 051, 052, 053, 055, 056, 057, 059, 061, 063 &\n\n065.\n\nRequirement: 1. Perform a visual inspection to detect corrosion or cracks in the wing rear beam/upper cap angle, wing upper aft plank, and the “clothespin” attach fitting, part number 1159WM20016, located at Fuselage Station 452.\n\n    2. Inspect the lower cavity of the “clothespin” attach fitting, using a 4.9 mm or smaller flexible borescope through the existing drain hole. If no drain hole exists, prior to further flight, install a drain hole in accordance with Gulfstream G-II Customer Bulletin No 42, Section V, dated December 15, 1969.\n\n    3. Inspect the upper cavity of the “clothespin” attach fitting, using the borescope through the gaps where the “clothespin” mates with the fitting. If foam filler is present and this inspection cannot be accomplished, perform the inspection in accordance with a scheme approved by the Authority.\n\n    4. Inspect the wing upper aft plank adjacent to the clothespin fitting for corrosion or defects using pulse echo ultrasonic equipment. (CAUTION: A machined step in this area may be misinterpreted as material loss.)\n\n    5. Replace any cracked or corroded parts in accordance with a scheme approved by the Authority.\n\nNote: FAA Emergency AD 90-13-02 refers.\n\nCompliance: Prior to 30 September 1990.\n\nBackground: There have been reports of extensive corrosion and cracking in the area of the Fus Sta 452 “clothespeg” attachment fitting. This is attributed to foam being used to retain the fitting nuts during production and the lack of drain holes in the attach fitting area. Corrosion in this area will substantially reduce wing integrity.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive maintains a focused scope: inspections and corrective action at fuselage station 452 for the listed serial numbers. It enforces specific inspection methods, drain‑hole installation per an existing Gulfstream bulletin, and replacement under Authority approval; there is no indication in the text that the scope was expanded beyond those aircraft or tasks."},"complexity_factors":["Narrow applicability limited to a specific list of serial numbers (Applicability).","Multiple inspection techniques required: visual inspection, borescope ≤4.9 mm, and pulse‑echo ultrasonic (Requirement 1,2,4).","Access constraints where foam filler blocks inspection; alternative schemes require approval from the Authority (Requirement 3).","Possible airframe modification: installing drain holes per Gulfstream G‑II Customer Bulletin No 42 when none exist (Requirement 2).","Removal and replacement of cracked or corroded parts subject to Authority‑approved schemes (Requirement 5).","Fixed compliance deadline (Prior to 30 September 1990) creates time pressure on operators (Compliance).","Reference to FAA Emergency AD and a historical Gulfstream bulletin increases cross‑jurisdictional technical reliance (Note; Requirement 2).","Safety‑critical consequence: corrosion can substantially reduce wing integrity, raising inspection and repair urgency (Background)."],"plain_english_summary":"This airworthiness directive requires operators of the listed Gulfstream G‑1159/G‑IV serial‑numbered aeroplanes to inspect the clothespin attach fitting and adjacent wing structure at fuselage station 452 for corrosion and cracking, using visual, borescope and pulse‑echo ultrasonic methods, install drain holes if missing, and replace defective parts. Operators must follow Authority‑approved repair/inspection schemes where needed (Requirement 1–5) and comply before 30 September 1990 (Compliance). Corrosion here can substantially reduce wing integrity."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope — addressing a specific safety defect in a specific aircraft component at a specific location. There is no evidence of scope creep; it remains tightly focused on the corrosion/cracking issue at Fuselage Station 452 as originally identified."},"complexity_factors":["Single, specific technical subject matter (one aircraft component at one location)","Only 5 numbered requirements with clear sequential logic","Limited applicability (52 specific serial numbers listed explicitly)","One cross-reference to FAA Emergency AD 90-13-02 for context","Minimal defined terms (only standard aviation terminology like 'Fuselage Station 452' and 'borescope')","Single compliance deadline with no conditional extensions or exceptions","Straightforward background explanation linking cause (foam + no drain holes) to effect (corrosion risk)"],"plain_english_summary":"Australia’s CASA issued an emergency Airworthiness Directive requiring owners/operators of 52 specific Gulfstream G‑II and G‑IV jets to urgently inspect a critical wing rear‑beam “clothespin” attach fitting at FS452 for corrosion and cracking.  \n\nThe AD mandates visual, borescope and ultrasonic inspections (with special procedures if foam blocks view) and replacement of damaged parts — prompted by trapped moisture from manufacturing foam and missing drain holes that can cause catastrophic wing failure (deadline 30 Sept 1990)."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-g1159-36-corrosion-and-cracking-fuselage-station-452","history":"/api/acts/ad-g1159-36-corrosion-and-cracking-fuselage-station-452/history","analysis":"/api/acts/ad-g1159-36-corrosion-and-cracking-fuselage-station-452/analysis","conflicts":"/api/acts/ad-g1159-36-corrosion-and-cracking-fuselage-station-452/conflicts","importantCases":"/api/acts/ad-g1159-36-corrosion-and-cracking-fuselage-station-452/important-cases","documents":"/api/acts/ad-g1159-36-corrosion-and-cracking-fuselage-station-452/documents"}}