{"id":"F2007L01226","name":"AD/HU 369/117 - Tail Rotor Blade Root Fitting","slug":"ad-hu-369-117-tail-rotor-blade-root-fitting","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65367,"registerId":"commonwealth-F2007L01226-current","compilationNumber":null,"startDate":"2026-04-02","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 369/117 | Tail Rotor Blade Root Fitting | 7/2007 TX |\n| ------------- | ----------------------------- | --------- |\n\n| Applicability: | Model 369, 369A, 369H, 369HM, 369HS, 369HE, 369D, 369E, 369F, and 369FF helicopters, equipped with a tail rotor blade part number 369A1613, 369D21606, 369D21613, 369D21615, or 421-088, all dash numbers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect each affected tail rotor blade for a smooth radius as follows:a. Remove the tail rotor blade assembly by following the Accomplishment Instructions, paragraphs 2.B.(1) through 2.B.(3), Part 2., of MD Helicopters Inc., Service Bulletin SB369H-247, SB369D-204, SB369E-099, and SB369F-084, dated 26 April 2007, as applicable.b. Using a bright light, inspect the bore of the tail rotor blade root fitting by following the Accomplishment Instructions, paragraphs 2.B.(4) and 2.B.(5),Part 2, and Figures 1 and 2 of the applicable service bulletin.c. Before further flight, replace each blade assembly that does not have a smooth radius by following the Accomplishment Instructions, paragraphs 2.B.(6) and 2.B.(7), Part 2, and Figure 2 of the applicable service bulletin.d. Identify the serviceable tail rotor blade assembly with the applicable model of helicopter by following the Identification, paragraphs 3.(1) through 3.(4) of the applicable service bulletin.Note 1: Special Flight permits will not be allowed.Note 2: FAA Emergency AD 2007-09-51 refers. |\n| Compliance:    | Before further flight after 1 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\n|                | This Airworthiness Directive becomes effective on 1 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n\n| Background: | The FAA received a report of an accident after the loss of a tail rotor blade. This condition, if not corrected, could result in the failure of a tail rotor blade and subsequent loss of control of the helicopter. |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n30 April 2007","sortOrder":0},{"sectionNumber":"AD/HU 369/117","sectionType":"part","heading":"AD/HU 369/117","content":"## AD/HU 369/117","sortOrder":1},{"sectionNumber":"Tail Rotor Blade Root Fitting","sectionType":"part","heading":"Tail Rotor Blade Root Fitting","content":"## Tail Rotor Blade Root Fitting","sortOrder":2},{"sectionNumber":"7/2007 TX","sectionType":"part","heading":"7/2007 TX","content":"## 7/2007 TX","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific safety defect in specific helicopter models. It has not expanded beyond its original purpose of preventing tail rotor blade failure."},"complexity_factors":["Multiple cross-references to external manufacturer service bulletins (SB369H-247, SB369D-204, SB369E-099, SB369F-084) rather than spelling out procedures in the AD itself","Technical aviation terminology requiring specialized knowledge (\"tail rotor blade root fitting\", \"smooth radius\", \"dash numbers\")","Nested applicability criteria combining aircraft models with specific part numbers across \"all dash numbers\" (variants)","Conditional compliance structure: inspect → if failed → replace → mark serviceable","Reference to foreign regulatory action (FAA Emergency AD 2007-09-51) for context but not binding instruction"],"plain_english_summary":"CASA requires immediate inspection and, if necessary, replacement of tail-rotor blades on McDonnell Douglas (Hughes) and Kawasaki Model 369 series helicopters with specified part numbers. Owners/operators must remove and inspect blade root fittings for a smooth radius and replace any defective blades before further flight; no special flight permits are allowed.  \n\nThe AD responds to an FAA report of an in‑flight tail‑rotor separation that can cause loss of directional control and catastrophic accidents."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD is narrowly targeted at preventing tail rotor blade failure on a defined set of 369‑series helicopters fitted with specified blade part numbers. It does not broaden scope beyond that safety objective: the instrument prescribes a single inspection/remedy pathway using manufacturer service bulletins, contains a firm compliance deadline and disallows special flight permits. There is no substantive expansion of purpose or mission creep compared with the AD’s stated intent to prevent loss of a tail rotor blade."},"complexity_factors":["Single, focused safety requirement (inspect and replace) — low intrinsic procedural complexity","Applicability lists 10 helicopter models and 5 tail rotor blade part numbers (moderate specificity)","Cross‑references to four model‑specific MD Helicopters service bulletins with multiple paragraph and figure citations (adds implementation complexity)","Binary compliance timing: \"before further flight after 1 May 2007\" (simple deadline)","Prohibition on special flight permits (Note 1) increases operational impact but not legal complexity","Reference to an FAA Emergency AD (Note 2) introduces an external document to consult","Requirement steps are linear (remove, inspect, replace, identify) rather than nested exceptions — reduces complexity"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- It requires operators of specific McDonnell Douglas (Hughes) and Kawasaki 369-series helicopters to inspect the *root fitting bore* (the hole where the tail rotor blade mounts) of certain tail rotor blade part numbers and to replace any blade that fails the inspection before the helicopter flies again. (Requirement a–d; Compliance.)\n\n- The inspections must be carried out by removing the tail rotor blade assembly and following the removal, inspection and replacement steps shown in the relevant MD Helicopters service bulletin for each model (the AD names SB369H‑247, SB369D‑204, SB369E‑099, and SB369F‑084 dated 26 April 2007). The AD also requires marking/identifying the serviceable blade assembly per the bulletin. (Requirement a–d.)\n\n- Special flight permits are explicitly disallowed: if the blade fails inspection, the helicopter cannot be ferried under a special permit to perform the corrective work. (Note 1.)\n\n- The AD became effective 1 May 2007 and requires compliance before further flight after that date. (Compliance.)\n\n**Who this affects**\n\n- Owners and operators of Model 369, 369A, 369H, 369HM, 369HS, 369HE, 369D, 369E, 369F, and 369FF helicopters when those helicopters are equipped with tail rotor blade part numbers 369A1613, 369D21606, 369D21613, 369D21615, or 421‑088 (all dash numbers). (Applicability.)\n\n- Maintenance organisations and mechanics who perform the removal, inspection and replacement in accordance with the MD Helicopters service bulletins referenced by the AD.\n\n**Why it matters (official rationale and practical implications)**\n\n- The regulator’s stated reason: the FAA reported an accident caused by the loss of a tail rotor blade. The AD says a non‑smooth radius in the blade root fitting bore could lead to blade failure and loss of control. The AD therefore mandates inspection and removal of any blade assembly that does not have a smooth radius. (Background; Requirement.)\n\n- Practical effects and the trade‑offs operators face:\n  - Who pays: owners/operators pay for labour, inspection time, and any replacement blades or parts required. If replacement blades must be purchased from a manufacturer or authorised supplier, that cost is concentrated on affected operators.\n  - Who decides: the regulator (Delegate of the Civil Aviation Safety Authority) mandates the action; the operator or maintainer chooses how and when to schedule the inspection and arranges procurement of replacement parts if needed. (AD text; signing delegate.)\n  - Behaviour changes: affected helicopters must be inspected and any failing blade replaced before flight; operators will schedule maintenance and possibly ground aircraft until compliance is achieved because special flight permits are prohibited. (Requirement; Note 1; Compliance.)\n  - Incentives and costs: the AD reduces the risk of in‑flight blade failure (the intended safety benefit) but imposes direct costs (parts, labour, downtime). The prohibition on special flight permits raises the cost of compliance because aircraft cannot be ferried to an alternate worksite under permit.\n  - Implementation risks: availability of replacement blades, lead times for parts or qualified maintenance, and correct interpretation/application of the service bulletin procedures could delay return to service. The AD cross‑references multiple service bulletin paragraphs and figures, so maintainers must ensure they use the correct bulletin for the helicopter model. (Requirement a–d.)\n  - Compliance burden and verification: inspect/remove/replace steps are detailed in the service bulletins; operators must keep records showing the inspection and any replacement and identification marking required by the bulletin.\n\n**Mechanisms that concentrate benefits or costs**\n\n- Concentrated costs: affected operators (a limited set of helicopter models with specific part numbers) bear replacement and downtime costs directly.\n\n- Concentrated benefit to parts/maintenance suppliers: if replacement blades or specialist services are required, those suppliers may see increased demand from a limited group of operators. The AD itself references manufacturer service bulletins as the method to comply, which channels repair work and parts procurement to established suppliers.\n\n**Net framing (mechanical summary followed by claim testing)**\n\n- The AD mechanically imposes an immediate, mandatory inspection and replacement requirement for listed helicopter models with listed blade part numbers, grounded by the rule that no aircraft with a failing blade may fly until corrected. (Requirement; Compliance; Note 1.)\n\n- The regulator’s safety claim (preventing tail rotor blade failure) is directly addressed by the inspection-and-replace mechanism. The main trade‑offs are the economic cost to operators, potential downtime and logistics (parts and qualified labour), and the operational impact of the prohibition on special flight permits. These trade‑offs create clear incentives for operators to promptly inspect and replace any defective blades but also create short‑term concentration of expense and possible supply pressure for replacement parts. (Background; Requirement; Notes.)"},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-117-tail-rotor-blade-root-fitting","history":"/api/acts/ad-hu-369-117-tail-rotor-blade-root-fitting/history","analysis":"/api/acts/ad-hu-369-117-tail-rotor-blade-root-fitting/analysis","conflicts":"/api/acts/ad-hu-369-117-tail-rotor-blade-root-fitting/conflicts","importantCases":"/api/acts/ad-hu-369-117-tail-rotor-blade-root-fitting/important-cases","documents":"/api/acts/ad-hu-369-117-tail-rotor-blade-root-fitting/documents"}}