{"id":"F2006B05987","name":"AD/PA-42/20 - Main Landing Gear Forward Side Brace","slug":"ad-pa-42-20-main-landing-gear-forward-side-brace","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":136200,"registerId":"commonwealth-F2006B05987-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-42/20 - Main Landing Gear Forward Side Brace","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-42/20 Main Landing Gear Forward Side Brace 8/90\n\nApplicability: PA-42-1000 Cheyenne 400/400LS with S/Nos 42-5527001 and up.\n\nRequirement: For aircraft with S/Nos 42-557001 through 42-5527035; Action in accordance with Piper Mandatory SB 817C, Parts I and II dated 21 May 1990, and\n\nFor aircraft with S/Nos 42-5527036 and up; Action in accordance with Piper Mandatory SB 817C Part II dated 21 May 1990.\n\nCompliance: For Part I: Unless already accomplished, prior to exceeding 100 hours time in\n\nservice, or at the next scheduled inspection for issue of Maintenance Release after 9 August 1990, whichever occurs later, and thereafter at intervals not exceeding 3000 hours time in service.\n\nFor Part II: Prior to exceeding 1800 hours time in service after initial installation and thereafter at periods not exceeding 200 hours time in service until 3000 hours time in service life limit is reached, and\n\nWhenever the landing gear has been extended at speeds above 170 knots IAS (VLo).\n\nBackground: Cracking has been experienced in the MLG forward side braces. Failure of a brace could lead to landing gear collapse. The manufacturer has considered replacement of original side braces with improved parts, together with repetitive inspections and a life limit on improved parts as mandatory.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2268},"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD addresses the specific safety issue of main landing gear forward side brace cracking as originally intended, with no expansion beyond this technical airworthiness concern."},"complexity_factors":["Bifurcated requirements based on aircraft serial number ranges","Multiple overlapping compliance timeframes (flight hours, calendar dates, and event-based triggers)","Technical aviation terminology requiring specialist knowledge (VLo, Time in Service, Maintenance Release)","Incorporation by reference to external technical document (Piper Mandatory SB 817C) without reproducing its content","Conditional logic distinguishing between Part I and Part II actions"],"plain_english_summary":"This AD mandates inspections and maintenance of the main landing gear forward side braces on Piper PA‑42‑1000 Cheyenne 400/400LS aircraft (S/N 42‑5527001 and up). Compliance follows Piper Service Bulletin 817C, with earlier serials requiring both Parts I & II and later serials only Part II, on specified intervals tied to flight hours and gear‑lowering events above VLo.\n\nThe rule responds to detected brace cracks that could cause landing‑gear collapse, posing serious damage and injury risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-42-20-main-landing-gear-forward-side-brace","history":"/api/acts/ad-pa-42-20-main-landing-gear-forward-side-brace/history","analysis":"/api/acts/ad-pa-42-20-main-landing-gear-forward-side-brace/analysis","conflicts":"/api/acts/ad-pa-42-20-main-landing-gear-forward-side-brace/conflicts","importantCases":"/api/acts/ad-pa-42-20-main-landing-gear-forward-side-brace/important-cases","documents":"/api/acts/ad-pa-42-20-main-landing-gear-forward-side-brace/documents"}}