{"id":"F2006B10671","name":"AD/HU 369/111 - Tail Rotor Blade Pitch Horn","slug":"ad-hu-369-111-tail-rotor-blade-pitch-horn","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116606,"registerId":"commonwealth-F2006B10671-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 CASR 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 369/111 Tail Rotor Blade Pitch Hor","sectionType":"part","heading":"AD/HU 369/111 Tail Rotor Blade Pitch Horn 6/2003","content":"# AD/HU 369/111 Tail Rotor Blade Pitch Horn 6/2003\n\nTX\n\nApplicability: Model 369A, D, E, H, HE, HM, HS, F, and FF helicopters; with tail rotor blades, part number 369D21640-501, 369D21641-501, 369D21642-501, 369D21643-501, 500P3100-101, 500P3100-301, 500P3300-501, or 500P3500-701, installed.\n\nRequirement: 1. Perform a one-time visual inspection of each tail rotor blade pitch horn for a crack or corrosion in the area indicated by Note 2 in Figure 1 of this Directive. Paint removal in accordance with Note 1 of Figure 1 of this Directive is not required for the visual inspection.\n\n    2. This Directive establishes a new retirement life of 400 hours time in service for affected tail rotor blades. For helicopters with an affected tail rotor blade installed that has between 390 and 700 hours time in service, remove and replace the tail rotor blade with a serviceable blade.\n    3. Revise the helicopter Airworthiness Limitations section of the maintenance manual to indicate the new retirement for affected tail rotor blades.\n\nFor helicopters with a tail rotor blade installed that has more than 700 hours time in service, a one-time special flight permit to fly to a repair facility may be issued only upon completion of an eddy current surface scan of each affected pitch horn (refer Figure 1). Paint removal in accordance with Note 1 of Figure 1 of this Directive is required for the surface scan. If a crack is found, before further flight, replace the cracked tail rotor blade with a serviceable blade.","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, targeted Airworthiness Directive addressing a specific unsafe condition in defined helicopter models. It has not expanded beyond its original safety purpose."},"complexity_factors":["Multiple specific part numbers listed (8 different part numbers in applicability)","Tiered compliance requirements based on flight hours (three distinct thresholds: <390, 390-700, >700 hours)","Conditional exception for over-700-hour blades requiring special flight permit and advanced inspection technique (eddy current scan)","Cross-reference to Figure 1 and Notes 1-2 (external diagram not included in text)","Requires manual revision (administrative compliance burden)"],"plain_english_summary":"This AD requires operators of specified McDonnell Douglas (Hughes) and Kawasaki 369 tail rotor blades to inspect the pitch horn for cracks/corrosion, retire blades at 400 flight hours, and replace ones with 390–700 hours. Records and maintenance manuals must be updated to show the new 400‑hour life limit. Blades over 700 hours may get one ferry flight to a repair facility only after an eddy‑current inspection with paint removal and no cracks found. It prevents catastrophic tail‑rotor failure."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"The directive introduces a new mandatory 400‑hour retirement life for the specified tail rotor blades and adds inspection, replacement and maintenance‑manual revision obligations. It therefore changes the lifecycle and inspection obligations for those blades by imposing mandatory retirement and conditional ferrying procedures where those specific limits and conditions did not apply in this form before."},"complexity_factors":["Multiple affected helicopter models and several specific tail rotor blade part numbers to identify and track","Two inspection regimes: a one‑time visual inspection versus an eddy‑current surface scan (the latter requires paint removal) depending on blade hours","A new fixed retirement life (400 hours) with transitional replacement requirement for blades between 390–700 hours","Administrative requirement to revise the Airworthiness Limitations section of maintenance manuals","Operational constraints tied to special flight permit issuance (conditional on scan results), creating potential short‑term ferrying and grounding logistics","Compliance enforcement depends on maintenance records and accurate time‑in‑service tracking"],"plain_english_summary":"This airworthiness directive requires operators of specified McDonnell Douglas (Hughes) and Kawasaki 369-series helicopters to inspect tail‑rotor blade pitch horns for cracking/corrosion, sets a new 400‑hour retirement life for listed tail rotor blades, requires replacement of blades in the 390–700 hour range, and limits ferry flights for blades over 700 hours to cases with a prior eddy‑current scan and paint removal. It affects owners/operators who must carry out inspections, make replacements, update maintenance limits and fund any repairs or grounded aircraft."},"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-369-111-tail-rotor-blade-pitch-horn","history":"/api/acts/ad-hu-369-111-tail-rotor-blade-pitch-horn/history","analysis":"/api/acts/ad-hu-369-111-tail-rotor-blade-pitch-horn/analysis","conflicts":"/api/acts/ad-hu-369-111-tail-rotor-blade-pitch-horn/conflicts","importantCases":"/api/acts/ad-hu-369-111-tail-rotor-blade-pitch-horn/important-cases","documents":"/api/acts/ad-hu-369-111-tail-rotor-blade-pitch-horn/documents"}}