{"id":"F2006B02631","name":"AD/B727/108 - Aileron Power Control Unit","slug":"ad-b727-108-aileron-power-control-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41947,"registerId":"commonwealth-F2006B02631-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/108 - Aileron Power Control Unit","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)  \nBoeing 727 Series Aeroplanes\n\nAD/B727/108 Aileron Power Control Unit 6/89\n\nApplicability: All model 727 series.\n\nRequirement: Unless already accomplished in accordance with National Water Lift SB 27-21-1/200 or NWL SB 27-10-1/200 Revision 1;\n\n    In accordance with Boeing Alert SB 727-27A0220: Remove and replace any aileron PCU which has accumulated 18000 or more hours since new or since piston seal replacement, OR\n\n    2. In accordance with Boeing Alert SB 727-27A0220: Remove any aileron PCU which has accumulated 18000 or more hours since new or since piston seal replacement and perform a hydraulic bench internal leakage check. Replace any aileron PCU which fails the internal leakage test.\n\nNote 1: Compliance to National Water Lift SB 27-21-1/200 or NWL SB 27-10-1/200 Revision 1 constitutes terminating action for this AD. NOTE 2. FAA AD 89-07-05 Amdt 39-6163 refers.\n\nCompliance: 1. Within the next 3000 hours time in service on the PCU, after 15 June 1989 and thereafter at intervals not exceeding 18,000 hours.\n\n2. Within the next 3,000 hours time in service on the PCU after 15 June 1989 and thereafter at intervals not exceeding 2,500 flight cycles.\n\nBackground: Incidents of aileron control wheel binding have been attributed to internal damage in the aileron power control unit. This damage was due to deterioration of the piston primary seals. Service experience indicates that significant seal deterioration can be anticipated on units that have accumulated 18,000 hours or more since new or last overhaul.","sortOrder":0}],"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical failure mode in a specific aircraft type. It has not expanded beyond its original purpose of preventing aileron control binding due to PCU seal deterioration."},"complexity_factors":["Single, specific mechanical component targeted (Aileron PCU)","Two clear alternative compliance paths (replacement vs. test-and-replace)","Simple hour/cycle-based triggering threshold (18,000 hours)","Minimal cross-referencing (only references two manufacturer service bulletins and one FAA AD)","Straightforward compliance timeline (3,000 hours from effective date, then recurring intervals)","No nested definitions or interpretation sections","Single applicability criterion (all Boeing 727 series models)"],"plain_english_summary":"This AD requires Australian operators of Boeing 727s to address aileron Power Control Unit (PCU) piston‑seal deterioration that can cause control wheel binding. PCUs at or beyond ~18,000 hours must be removed and either replaced or bench‑tested for internal leaks (and replaced if they fail). Work is due within 3,000 flight hours after 15 June 1989 and repeated every 18,000 hours (or every 2,500 cycles if using the test option). It prevents potential loss‑of‑control incidents."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive targets PCUs with 18,000+ hours to address piston-seal deterioration causing aileron control wheel binding. It applies to all Model 727 aircraft and offers terminating action if specified National Water Lift service bulletins have been complied with; the scope aligns with that stated purpose."},"complexity_factors":["Clear technical threshold: action required once a PCU reaches 18,000 hours since new or since piston seal replacement.","Two compliance paths: mandatory removal/replacement or removal plus hydraulic bench internal leakage check with conditional replacement on test failure.","Multiple time metrics to track: hours since new/repair and flight cycles (compliance intervals include 3,000 hours and 2,500 flight cycles).","Dependence on Boeing Alert Service Bulletin procedures for method and on National Water Lift SBs for terminating action.","Applicability to all Boeing 727 models increases operator population affected and record-keeping burden.","Safety-critical maintenance requiring removal from the aircraft and bench testing, creating parts, labour and outage costs for operators.","Notes reference external ADs and service documents, creating cross-document compliance verification needs."],"plain_english_summary":"This directive requires operators of Boeing 727 aircraft to remove-and-replace, or inspect and replace if needed, any aileron power control unit (PCU) that has reached 18,000 hours since new or since the piston seal was last replaced, using Boeing service bulletin procedures. It responds to reported piston-seal deterioration linked to aileron control wheel binding; aircraft owners/operators pay for the work and must track PCU hours and flight cycles to meet the directive's compliance windows."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-108-aileron-power-control-unit","history":"/api/acts/ad-b727-108-aileron-power-control-unit/history","analysis":"/api/acts/ad-b727-108-aileron-power-control-unit/analysis","conflicts":"/api/acts/ad-b727-108-aileron-power-control-unit/conflicts","importantCases":"/api/acts/ad-b727-108-aileron-power-control-unit/important-cases","documents":"/api/acts/ad-b727-108-aileron-power-control-unit/documents"}}