{"id":"F2006B06798","name":"AD/SC7/24 - Main Landing Gear Shock Absorber Attachment Pin","slug":"ad-sc7-24-main-landing-gear-shock-absorber-attachment-pin","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114655,"registerId":"commonwealth-F2006B06798-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SC7/24 - Main Landing Gear Shock Absorber Attachment Pin","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)  \nShort SC7 (Skyvan) Series Aeroplanes\n\nAD/SC7/24 Main Landing Gear Shock Absorber Attachment Pin 10/95\n\nApplicability: All Skyvan MK 3, 3A, 3M and Skyliner series aircraft fitted with main landing gear type numbers EH1831-D, EH1832-D, EH1837-B, EH1838-B, EH1885-1 and EH1886-1.\n\nRequirement: Replace the main landing gear shock absorber attachment pin P/N EH183113 with a new pin of the same P/N or with a new design pin, P/N 200621639.\n\nNote: CAA(UK) AD 004-04-81 refers.\n\nCompliance: If pin P/N EH183113 has exceeded 5280 landings, replace before 14 November 1995 or before 300 landings after 14 September 1995, whichever is the sooner.\n\nContinue to replace pin P/N EH183113 at 5280 landing intervals, replace pin P/N 200621639 at 23 000 landing intervals.\n\nBackground: A life limitation has been established on main landing gear shock absorber attachment pin. Installation of a new part number pin provides a substantial increase in fatigue life.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused on one specific part on one specific aircraft type. It has not expanded beyond its original safety purpose."},"complexity_factors":["Single, specific mechanical component addressed","Only 6 defined aircraft/landing gear variants in applicability","Clear binary compliance path (old pin vs new pin)","Simple arithmetic compliance trigger (landing counts)","No nested exceptions or conditional sub-clauses","Background section provides plain explanation of safety rationale","Total length: approximately 150 words"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it like a compulsory recall notice, but for aircraft parts rather than cars.\n\n**What it does:** It orders owners and operators of specific Short SC7 Skyvan aircraft to replace a particular bolt (the \"main landing gear shock absorber attachment pin\") that holds the plane's landing gear together. \n\n**Who it affects:** Anyone who owns or operates Short SC7 Skyvan MK 3, 3A, 3M or Skyliner aircraft with specific landing gear model numbers (EH1831-D, EH1832-D, EH1837-B, EH1838-B, EH1885-1 and EH1886-1).\n\n**The safety issue:** The original pin (part number EH183113) wears out after about 5,280 landings. If not replaced, it could fail due to metal fatigue — potentially causing the landing gear to collapse. There's a newer, stronger pin available (part number 200621639) that lasts much longer (23,000 landings).\n\n**What must be done:**\n- **If your old pin has already done 5,280+ landings:** Replace it by 14 November 1995, or within 300 more landings after 14 September 1995 — whichever comes first\n- **Going forward:** Keep replacing the old-style pin every 5,280 landings, OR upgrade to the new-style pin and replace it only every 23,000 landings\n\n**Why it matters:** This prevents catastrophic landing gear failure. The directive references a UK safety notice (CAA(UK) AD 004-04-81), showing this is part of international aviation safety coordination."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This directive establishes a life limitation and mandatory replacement requirement for the specified shock absorber attachment pin and introduces a new-design part with a longer fatigue life. It does not broaden applicability beyond the listed Skyvan/Skyliner models or add other component types; it replaces an unbounded service practice with defined landing-count limits and explicit deadlines."},"complexity_factors":["Narrow applicability to specific aircraft models and multiple listed landing-gear type numbers (affects only certain Skyvan/Skyliner aircraft).","Two specific part numbers involved (old P/N EH183113 and new-design P/N 200621639) and permission to replace with either part.","Different life limits for each part (5,280 landings for EH183113; 23,000 for 200621639) requiring distinct tracking.","Conditional compliance timing: fixed calendar deadline plus a ‘whichever is sooner’ provision tied to landing counts (adds scheduling complexity).","Ongoing maintenance regime: continued replacement at specified landing intervals (recurring compliance and record-keeping burden).","Operational administration: operators must monitor and record landings accurately to determine replacement triggers."],"plain_english_summary":"Requires owners/operators of Skyvan MK3, 3A, 3M and Skyliner aircraft fitted with listed main landing gear types to replace shock absorber attachment pin P/N EH183113 with either the same P/N or a new-design P/N 200621639. The directive sets life limits (5,280 landings for EH183113; 23,000 for 200621639) and imposes specified compliance deadlines. CASA issued the directive; operators pay replacement costs and must track landing counts to meet the intervals."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sc7-24-main-landing-gear-shock-absorber-attachment-pin","history":"/api/acts/ad-sc7-24-main-landing-gear-shock-absorber-attachment-pin/history","analysis":"/api/acts/ad-sc7-24-main-landing-gear-shock-absorber-attachment-pin/analysis","conflicts":"/api/acts/ad-sc7-24-main-landing-gear-shock-absorber-attachment-pin/conflicts","importantCases":"/api/acts/ad-sc7-24-main-landing-gear-shock-absorber-attachment-pin/important-cases","documents":"/api/acts/ad-sc7-24-main-landing-gear-shock-absorber-attachment-pin/documents"}}