{"id":"F2009L03362","name":"AD/HU 369/48 Amdt 1 - Main Rotor Lead-Lag Bolts - Inspection for Corrosion","slug":"ad-hu-369-48-amdt-1-main-rotor-lead-lag-bolts-inspection-for-corrosion","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":140929,"registerId":"commonwealth-F2009L03362-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"McDonnell Douglas (Hughes) and Kawasaki ","sectionType":"division","heading":"McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters","content":"### McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters\n\n| AD/HU 369/48 Amdt 1 | Main Rotor Lead-LagBolts - Inspection for Corrosion | 10/2009 |\n| ------------------- | --------------------------------------------------- | ------- |\n\n| Applicability: | All model 369H series helicopters.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | In accordance with the procedures laid down in Section 7 of the Basic H.M.I., inspect the inner bores of the lead-lag bolts for presence of corrosion. If corrosion is found, treat bolts in accordance with the manufacturer’s instructions.                                                                                                                                                                                                                                                                                                                                                                                                       |\n| Compliance:    | Within 100 hours TIS after 31 July 1981 and thereafter at intervals not exceeding 300 hours TIS.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n|                | This Amendment becomes effective on 24 September 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| Background:    | There has been one local occurrence of failure of a lead-lag bolt on a model 369H helicopter and another found corroded, frozen and cracked. The failed bolt was believed to have been caused by hydrogen embrittlement induced from a corrosion reaction inside the lower bore of the bolt. As there is no specific scheduled inspection of the lead-lag bolts in the HMI inspection schedules, this AD was found necessary. Amendment 1 to this AD is raised to remove reference to the 369D helicopter as no reports of bolt failures, corrosion or cracking have been received regarding this model. Compliance with this AD remains unchanged. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n14 August 2009","sortOrder":0},{"sectionNumber":"AD/HU 369/48 Amdt 1","sectionType":"part","heading":"AD/HU 369/48 Amdt 1","content":"## AD/HU 369/48 Amdt 1","sortOrder":1},{"sectionNumber":"Main Rotor Lead-LagBolts - Inspection fo","sectionType":"part","heading":"Main Rotor Lead-LagBolts - Inspection for Corrosion","content":"## Main Rotor Lead-Lag  \nBolts - Inspection for Corrosion","sortOrder":2},{"sectionNumber":"10/2009","sectionType":"part","heading":"10/2009","content":"## 10/2009","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment narrows scope by removing the 369D model from applicability; the directive now applies only to 369H series helicopters. The inspection requirement, intervals and compliance obligations remain unchanged."},"complexity_factors":["Narrow applicability: applies only to McDonnell Douglas/Kawasaki 369H series (limited fleet size reduces complexity).","External-procedure dependency: inspection procedure references Section 7 of the Basic H.M.I., creating a dependency on another document for operational detail.","Manufacturer discretion for remediation: if corrosion is found, treatment follows manufacturer instructions rather than prescriptive steps, introducing variable cost and outcome.","Fixed, recurring compliance intervals: initial and repetitive TIS timeframes (100 hours then ≤300 hours) create ongoing scheduling and recordkeeping obligations.","Amendment altered scope: removal of 369D from applicability requires operators to check model coverage and may affect previous compliance assumptions.","Safety rationale tied to specific failure mode (hydrogen embrittlement): inspection targets a technical corrosion mechanism rather than a broad systems check."],"plain_english_summary":"This airworthiness directive requires operators of McDonnell Douglas/Kawasaki 369H helicopters to inspect the inner bores of main-rotor lead‑lag bolts for corrosion using the procedures in Section 7 of the Basic H.M.I., and to treat any corrosion per the manufacturer’s instructions. Inspections must be done within 100 hours time-in-service after 31 July 1981 and then at intervals not exceeding 300 hours TIS. CASA issues the requirement; operators pay inspection and treatment costs and will incur recurring maintenance and reliance on manufacturer remedies to reduce risk of bolt failure."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":true,"description":"The scope has narrowed from the original directive. Amendment 1 specifically removes the 369D helicopter model from coverage, restricting the AD to only the 369H series. This is a reduction in scope based on operational experience showing no defects in the excluded model."},"complexity_factors":["Very short document (approximately 250 words of substantive content)","Only 1 defined term implied ('TIS' — Time In Service, a standard aviation term)","Single, straightforward requirement with no nested conditions or exceptions","No cross-references to other legislation or complex procedural rules","Clear, linear structure: applicability → requirement → compliance → background","Amendment simplifies rather than complicates (removes one model from scope)"],"plain_english_summary":"This AD requires owners/operators of Hughes/Kawasaki 369H series helicopters to inspect main-rotor lead‑lag bolts for internal corrosion and treat any corrosion per manufacturer instructions. It narrows scope to 369H (369D removed), sets initial and recurring inspection intervals, and aims to prevent bolt failure from hydrogen embrittlement that could cause catastrophic rotor loss."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-48-amdt-1-main-rotor-lead-lag-bolts-inspection-for-corrosion","history":"/api/acts/ad-hu-369-48-amdt-1-main-rotor-lead-lag-bolts-inspection-for-corrosion/history","analysis":"/api/acts/ad-hu-369-48-amdt-1-main-rotor-lead-lag-bolts-inspection-for-corrosion/analysis","conflicts":"/api/acts/ad-hu-369-48-amdt-1-main-rotor-lead-lag-bolts-inspection-for-corrosion/conflicts","importantCases":"/api/acts/ad-hu-369-48-amdt-1-main-rotor-lead-lag-bolts-inspection-for-corrosion/important-cases","documents":"/api/acts/ad-hu-369-48-amdt-1-main-rotor-lead-lag-bolts-inspection-for-corrosion/documents"}}