{"id":"F2006B10668","name":"AD/HU 369/109 - Tail Rotor Gearbox Attachment","slug":"ad-hu-369-109-tail-rotor-gearbox-attachment","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116600,"registerId":"commonwealth-F2006B10668-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)\n\nMcDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters","sortOrder":0},{"sectionNumber":"AD/HU 369/109 Tail Rotor Gearbox Attachm","sectionType":"part","heading":"AD/HU 369/109 Tail Rotor Gearbox Attachment 10/2002","content":"# AD/HU 369/109 Tail Rotor Gearbox Attachment 10/2002\n\nApplicability: MD Helicopters Inc. Model 369D, 369E, 369F, and 369FF helicopters, modified in accordance with Aerometals Supplemental Type Certificate (STC) SH5055NM or SH4801NM.\n\nRequirement: 1. Initial Inspection and bolt replacement:\n\n    Carry out an inspection of the tail rotor gearbox attachment bolts to determine the part number.\n\n    b. If the part number cannot be determined or if the bolt is not P/N NAS1304- 26, replace the bolt with bolt, P/N NAS1304-26.\n    c. Torque the bolt to 100-110 in- lbs and apply slippage mark.\n\n    d. Remove the tailboom control rod and determine the number of threads protruding from each nutplate on the internal surface of the aft tailboom frame casing, P/N 369D23503, as shown in Figure 1 of this Directive. At least one thread must protrude. If more than four threads protrude, add an additional washer, P/N AN960D416, under the bolt head.\n\n    e. Torque the bolt to 100-110 in- lbs and re apply slippage mark.","sortOrder":1},{"sectionNumber":"2. Repetitive Inspection:","sectionType":"part","heading":"2. Repetitive Inspection:","content":"## 2. Repetitive Inspection:\n\n    Re check the attachment bolts for correct torque and re-torque if necessary.\n\n    b. Re apply slippage mark if re-torque is required.\n\nNote: FAA AD 2002-13-05 Amdt 39-12793 refers.","sortOrder":2},{"sectionNumber":"Figure 1 — Inspection Location","sectionType":"part","heading":"Figure 1 — Inspection Location","content":"## Figure 1 – Inspection Location\n\n![](image.002.jpeg)  \n\nCompliance: 1. Initial Inspection and bolt replacement:\n\nWithin 25 flight hours from the effective date of this Directive.","sortOrder":3}],"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with focused scope addressing a specific unsafe condition in defined aircraft models. The scope remains tightly constrained to the tail rotor gearbox attachment bolt issue as originally intended."},"complexity_factors":["Single specific mechanical issue (bolt replacement and torque checking)","Limited applicability (only 4 helicopter models with specific modifications)","Clear sequential steps with defined timeframes","Only 2 main compliance phases (initial and repetitive)","Minimal cross-referencing (one note to FAA AD 2002-13-05)","Straightforward measurement requirements (thread count, torque values in inch-pounds)","No nested exceptions or conditional logic beyond the basic 'if wrong bolt, replace' decision tree"],"plain_english_summary":"This safety order requires owners/operators of MD Helicopters 369D/E/F/FF modified under Aerometals STC SH5055NM or SH4801NM to inspect and, if necessary, replace the tail-rotor gearbox attachment bolts. Within 25 flight hours they must verify bolt part number (replace with P/N NAS1304-26 if incorrect/unknown), torque and mark the bolt, and perform short-interval repeat checks until the bolt remains secure. It’s mandatory to prevent possible tail-rotor detachment and loss of control."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive, as written, applies to the listed MD Helicopter models modified by the two named Aerometals STCs and prescribes inspection and corrective actions. The text contains no express amendment or expansion of an earlier instrument’s applicability; it references an FAA AD but does not on its face change or broaden the stated scope."},"complexity_factors":["Technical specificity: exact part numbers and torque values required (Requirement 1.b, 1.c).","Physical access and measurement: removal of the tailboom control rod to inspect thread protrusion inside aft tailboom casing (Requirement 1.d).","Iterative compliance: short, repeated inspection intervals (every 2–10 flight hours) until stability is achieved (Compliance: Repetitive Inspection).","Narrow applicability: applies only to specified MD Helicopter models modified by two specific Aerometals STCs (Applicability).","Implementation actions: possible part replacement, addition of washer, application of slippage marks — hands‑on maintenance tasks (Requirement 1.b–1.e).","Regulatory provenance: issued under subregulation 39.1(1) of CAR 1998 and cross‑references FAA AD 2002‑13‑05 (introductory text; Note)."],"plain_english_summary":"This Airworthiness Directive requires operators of MD Helicopters Models 369D, 369E, 369F and 369FF modified by Aerometals STC SH5055NM or SH4801NM to inspect tail‑rotor gearbox attachment bolts, replace non‑conforming bolts with P/N NAS1304‑26, torque to 100–110 in‑lbs, check thread protrusion in the aft tailboom and add a washer if needed, and carry out repeated torque checks every 2–10 flight hours until no bolt movement occurs.\n\nCASA states the action corrects an unsafe condition; the direct costs and labour fall to aircraft owners/operators, who must perform hands‑on and recurring maintenance under the AD."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-109-tail-rotor-gearbox-attachment","history":"/api/acts/ad-hu-369-109-tail-rotor-gearbox-attachment/history","analysis":"/api/acts/ad-hu-369-109-tail-rotor-gearbox-attachment/analysis","conflicts":"/api/acts/ad-hu-369-109-tail-rotor-gearbox-attachment/conflicts","importantCases":"/api/acts/ad-hu-369-109-tail-rotor-gearbox-attachment/important-cases","documents":"/api/acts/ad-hu-369-109-tail-rotor-gearbox-attachment/documents"}}