{"id":"F2006B05988","name":"AD/PA-42/21 - Main Landing Gear Upper Strut Housing","slug":"ad-pa-42-21-main-landing-gear-upper-strut-housing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":136202,"registerId":"commonwealth-F2006B05988-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-42/21 - Main Landing Gear Upper Strut Housing","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)  \nPiper PA-42 (Cheyenne III) Series Aeroplanes\n\nAD/PA-42/21 Main Landing Gear Upper Strut Housing 5/95\n\nApplicability: Piper PA-42-1000 Cheyenne 400/400LS, S/N 42-5527001 to 42-5527044, equipped with P/N 75215-04 main landing gear upper strut housings.\n\nRequirement: Dye penetrant inspect the main landing gear upper strut housing in accordance with Piper Service Bulletin No 929A.\n\nCompliance: Inspect before 450 hours time in service or before 100 hours time in service after\n\n27 April 1995, whichever is the later. Re-inspect at intervals not to exceed 100 hours time in service.\n\nNote: Installation of new P/N 75215-06 upper strut housing cancels the applicability of this AD.\n\nBackground: Piper have found that the main landing gear upper strut housing may develop cracks which could cause loss of structural integrity of the main landing gear.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2713},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument maintains its original targeted scope as a mandatory safety directive addressing a specific defective component in a defined aircraft fleet. No expansion beyond the original safety purpose is evident."},"complexity_factors":["Incorporates external technical document by reference (Piper Service Bulletin No 929A) without reproducing inspection procedures","Applicability limited by specific aircraft serial number range and part number","Dual-trigger compliance deadline requiring calculation based on accumulated flight hours and fixed calendar date","Recurring inspection obligation at defined intervals"],"plain_english_summary":"This AD requires recurring dye-penetrant inspections of the main landing-gear upper strut housings on Piper PA-42-1000 Cheyenne 400/400LS (S/N 42-5527001–42-5527044) equipped with P/N 75215-04 to detect cracks that could cause gear collapse. \n\nInspections must be repeated at intervals not exceeding 100 flight hours; installing a replacement housing P/N 75215-06 permanently removes the inspection requirement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-42-21-main-landing-gear-upper-strut-housing","history":"/api/acts/ad-pa-42-21-main-landing-gear-upper-strut-housing/history","analysis":"/api/acts/ad-pa-42-21-main-landing-gear-upper-strut-housing/analysis","conflicts":"/api/acts/ad-pa-42-21-main-landing-gear-upper-strut-housing/conflicts","importantCases":"/api/acts/ad-pa-42-21-main-landing-gear-upper-strut-housing/important-cases","documents":"/api/acts/ad-pa-42-21-main-landing-gear-upper-strut-housing/documents"}}