{"id":"F2006B10699","name":"AD/HU 369/37 - Tail Rotor Swashplate Bearing Locknut - Inspection and Increase in Torque","slug":"ad-hu-369-37-tail-rotor-swashplate-bearing-locknut-inspection-and-increase-in-torque","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116662,"registerId":"commonwealth-F2006B10699-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/37 - Tail Rotor Swashplate Bearing Locknut - Inspection and Increase in Torque","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)  \nMcDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters\n\nAD/HU 369/37 Tail Rotor Swashplate Bearing Locknut \\- Inspection and Increase in Torque\n\n  \n6/79\n\nApplicability: All model 369D with S/Nos. from 0003D to 0409D, not modified in accordance with Hughes SIN DN-37.\n\nRequirement: 1. Visually inspect the tail rotor swashplate bearing as follows;\n\n    (a) Pull back the non-rotating boot P/N 369D21806 from the tail rotor pitch control assembly P/N 369D21800 and check the locknut and tang washer by hand for looseness.\n\n    (b) If the locknut or tang washer is loose, remove and replace the tail rotor pitch control assembly with a serviceable assembly with a white dot on the locknut, before further flight.\n\n2. Modify the tail rotor swashplate in accordance with Hughes SIN DN-37. For aircraft maintained in accordance with ANO 100.5.1, Part 1 of this Directive shall be entered on the maintenance release as maintenance required. The inspection may be performed by the pilot in command, in which case certification is not required. In all other cases certification may be made on the maintenance release. This inspection may also be performed and certified by any Licensed Aircraft Maintenance Engineer.\n\nCompliance: For Part 1 \\- At each preflight inspection, until modified in accordance with Part 2.\n\nFor Part 2 \\- Within 100 hours time in service after 10 May 1979.\n\nBackground: To prevent loosening of the tail rotor swashplate bearing locknut and possible loss of tail rotor control, the tightening torque of the locknut is increased. Until this is accomplished, the locknut is to be inspected prior to each flight.\n\ns","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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope — addressing a specific mechanical defect in a defined helicopter model range. There is no evidence of scope creep; it remains tightly focused on the tail rotor swashplate bearing locknut issue as originally identified."},"complexity_factors":["Single, specific mechanical issue with clear applicability criteria (specific model and serial number range)","Straightforward two-part compliance structure (temporary inspection + permanent modification)","Minimal defined terms (only standard aviation abbreviations like P/N for Part Number, S/N for Serial Number, SIN for Service Instruction)","No nested exceptions or conditional logic beyond the basic 'if loose, then replace' instruction","Clear compliance deadlines and responsible parties specified","Short document (approximately 250 words) with single-purpose focus"],"plain_english_summary":"This airworthiness directive requires operators of Hughes/Kawasaki 369D helicopters (S/N 0003D–0409D) to perform a preflight visual check of the tail rotor swashplate locknut/tang washer and replace the pitch control assembly if loosened, and to complete a permanent modification per Hughes Service Instruction DN‑37 within 100 flight hours to increase locknut torque.\n\nIt affects owners/operators, pilots (who may do the preflight check), and maintenance engineers who certify the work — preventing tail-rotor loosening and potential loss of directional control."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive enforces the original safety objective stated in the text—to prevent locknut loosening and potential loss of tail-rotor control—by requiring interim inspections and a permanent modification for the specified SN range. It does not expand applicability beyond the listed models/serials or add unrelated obligations."},"complexity_factors":["Narrow applicability defined by model and serial-number range (Applicability)","Two-step requirement: repeated preflight inspections (Part 1) until a mandated modification is done (Part 2)","Different certification routes: pilot may perform uncertified preflight inspections vs. maintenance-release certification by licensed engineers or under ANO 100.5.1 (Requirement)","Mandatory modification referenced to external service information (Hughes SIN DN-37), creating dependency on manufacturer documentation","Specific operational compliance timing: ‘each preflight until modified’ and ‘within 100 hours after 10 May 1979’ (Compliance)","Concrete replacement criterion: assembly must bear a white dot to be serviceable, raising stocking/parts-control implications (Requirement)"],"plain_english_summary":"This airworthiness directive requires operators of specified McDonnell Douglas (Hughes)/Kawasaki 369D helicopters (S/N 0003D–0409D not modified per Hughes SIN DN-37) to inspect the tail rotor swashplate bearing locknut at each preflight until the swashplate is modified, and to complete that modification (Hughes SIN DN-37) within 100 hours after 10 May 1979. If the locknut or tang washer is loose, the tail rotor pitch control assembly must be replaced with a serviceable unit marked with a white dot before further flight.\n\nPilots may perform the preflight inspection without certification; otherwise a licensed Aircraft Maintenance Engineer or appropriate maintenance release must record and certify the inspection or modification. Operators bear the inspection and modification costs and must schedule the corrective work."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-37-tail-rotor-swashplate-bearing-locknut-inspection-and-increase-in-torque","history":"/api/acts/ad-hu-369-37-tail-rotor-swashplate-bearing-locknut-inspection-and-increase-in-torque/history","analysis":"/api/acts/ad-hu-369-37-tail-rotor-swashplate-bearing-locknut-inspection-and-increase-in-torque/analysis","conflicts":"/api/acts/ad-hu-369-37-tail-rotor-swashplate-bearing-locknut-inspection-and-increase-in-torque/conflicts","importantCases":"/api/acts/ad-hu-369-37-tail-rotor-swashplate-bearing-locknut-inspection-and-increase-in-torque/important-cases","documents":"/api/acts/ad-hu-369-37-tail-rotor-swashplate-bearing-locknut-inspection-and-increase-in-torque/documents"}}