{"id":"F2006B09627","name":"AD/F100/26 - MLG Main Fitting Sub-Assembly","slug":"ad-f100-26-mlg-main-fitting-sub-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54406,"registerId":"commonwealth-F2006B09627-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F100/26 - MLG Main Fitting Sub-Assembly","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)  \nFokker F100 (F28 Mk 100) Series Aeroplanes\n\nAD/F100/26 MLG Main Fitting Sub-Assembly 4/99\n\nApplicability: F.28 Mk.0100 aircraft, all serial numbers equipped with Messier-Dowty MLG Part Number (P/N) 201072011, 201072012, 201072013, 201072014, 201072015, or\n\n201072016; and Messier-Dowty MLG Main Fitting Sub-Assemblies P/N 201072283, 201072284, and 201251258.\n\nRequirement: 1. Inspect MLG Main Fitting Sub-Assemblies, P/N 201072283, 201072284, and 201251258, in accordance with Part A.(3) of Section 3 of the Accomplishment Instructions of Messier-Dowty Service Bulletin (SB) F100-32-86.\n\n2. Re-inspect and rework in accordance with Parts A.(4) and/or A.(5), as applicable, of Section 3. Accomplishment Instructions of Messier-Dowty SB F100-32-86. Report findings to Messier-Dowty Limited, or to the regional Messier-Dowty Customer Support Centre.\n\nNote: RLD BLA 1996-133(A) refers.\n\nCompliance: 1. For affected Parts fitted to aircraft, within six months of the effective date of this Directive.\n\nFor affected Parts not fitted to an aircraft, within six months of the effective date of this Directive or before flight, whichever occurs last.\n\nNote: There is a possibility of the above parts being held as spares. These parts could be affected by the same problem, hence a requirement to inspect such stocks prior to use.\n\n2. Before further flight, if any defects are found during the inspection in accordance with Requirement 1.\n\nThis Airworthiness Directive becomes effective on 22 April 1999.\n\nBackground: A report has been received of a cracked main fitting sub-assembly of a Messier- Dowty MLG installed on a F.28 Mk.0100 aircraft. The crack extended from the area of the side stay attachment lug to the base of the main fitting. Apparently, the crack initiated from the bottom of the affected lug’s internal diameter. Investigation revealed that the failure was caused by corrosion of the area, resulting from damage to the surface protection during honing of the bushes.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Scope targets the listed Messier‑Dowty main fitting sub‑assembly part numbers on F.28 Mk.0100 aircraft and spare stocks to address the reported corrosion‑initiated cracking. The directive confines obligations to inspection, re‑inspection/rework where defects are found, and reporting, without expanding to unrelated parts or broader design changes."},"complexity_factors":["Applicability lists multiple specific part numbers and covers both installed parts and spares (Applicability; Compliance).","Mandates inspections and conditional rework but delegates procedural detail to Messier‑Dowty Service Bulletin F100‑32‑86 (Requirement 1–2).","Different compliance timing rules for fitted parts versus spares and immediate repair-before-flight rule for detected defects (Compliance).","Mandatory reporting of findings to manufacturer or regional support centre creates an ongoing administrative obligation (Requirement 2).","Cross-reference to an external document (RLD BLA 1996-133(A)) increases traceability requirements for implementers (Note)."],"plain_english_summary":"This Airworthiness Directive requires owners/operators of Fokker F100 (F28 Mk 100) aeroplanes fitted with specified Messier‑Dowty main fitting sub‑assembly part numbers to inspect those parts and, if defects are found, perform re‑inspection and rework per Messier‑Dowty Service Bulletin F100‑32‑86 and report the findings. Inspections must be done within six months (or before flight for spares) and any defects must be repaired before further flight. Compliance and costs fall to aircraft operators and their maintenance organisations; the measure responds to corrosion‑initiated cracking from damaged surface protection."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of mandating inspection and repair of corroded landing gear components."},"complexity_factors":["Single, specific technical requirement with clear manufacturer reference (Service Bulletin F100-32-86)","Two-part compliance structure (initial inspection + conditional re-inspection/rework)","Dual applicability (parts fitted to aircraft vs. spare parts inventory)","Minimal defined terms (only standard aviation abbreviations: MLG, P/N, SB)","No nested legislative cross-references — references only external technical document (Service Bulletin)","Straightforward temporal compliance (6 months from effective date or before flight)"],"plain_english_summary":"This Airworthiness Directive orders inspections of specific Messier-Dowty main landing‑gear fitting sub‑assemblies on Fokker F100s, with mandated re‑inspection and repair per manufacturer instructions and deadlines (within six months of 22 Apr 1999, or before next flight if parts aren’t yet fitted). Defects found must be reported to the manufacturer before flight.\n\nIt targets Fokker F100 operators and maintenance organisations (including spare‑parts holders) after corrosion from damaged protective coating during honing caused a cracked fitting that could lead to catastrophic landing‑gear failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f100-26-mlg-main-fitting-sub-assembly","history":"/api/acts/ad-f100-26-mlg-main-fitting-sub-assembly/history","analysis":"/api/acts/ad-f100-26-mlg-main-fitting-sub-assembly/analysis","conflicts":"/api/acts/ad-f100-26-mlg-main-fitting-sub-assembly/conflicts","importantCases":"/api/acts/ad-f100-26-mlg-main-fitting-sub-assembly/important-cases","documents":"/api/acts/ad-f100-26-mlg-main-fitting-sub-assembly/documents"}}