{"id":"F2007L04222","name":"AD/F50/88 Amdt 1 - Power Plant - Feathering Pump","slug":"ad-f50-88-amdt-1-power-plant-feathering-pump","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":70424,"registerId":"commonwealth-F2007L04222-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Fokker F50 (F27 Mk 50) Series Aeroplanes","sectionType":"division","heading":"Fokker F50 (F27 Mk 50) Series Aeroplanes","content":"### Fokker F50 (F27 Mk 50) Series Aeroplanes\n\n| AD/F50/88 Amdt 1 | Power Plant - Feathering pump | 13/2007 TX |\n| ---------------- | ----------------------------- | ---------- |\n\n| Applicability: | Model F.27 Mk.50, 0502 and 0604 aeroplanes all serial numbers, unless the engines that are installed have previously been modified in accordance with Fokker Service Bulletin (SB) SBF50-61-024 Revision 1 dated 4 July 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Visually inspect both engines externally in two specific areas for any indication of oil leakage in accordance with the instructions detailed in Fokker Services All Operator Message AOF50.037 (ref TS04.57535) dated 2 November 2004.The pilot may carry out Requirement 1 of this AD provided the pilot has completed an approved training program.Note 1: Fokker Services All Operator Message AOF50.037 includes graphics to show the specific areas that need to be inspected.2. If any indication of oil leakage is found during the inspection as detailed in Requirement 1 of this AD, perform a detailed inspection for oil leakage at the feathering pump of the affected engine in accordance with Part 1 of the Accomplishment Instructions of Fokker Services SB F50-61-023 Revision 1 dated 4 July 2007 or later NAA approved revision.3. Perform a detailed inspection for oil leakage at the feathering pump on both engines in accordance with Part 1 of the Accomplishment Instructions of Fokker Services SB F50-61-023 Revision 1 dated 4 July 2007 or later NAA approved revision.4. If during the inspection as detailed in Requirement 2 or 3 of this AD, oil leakage is found at the feathering pump mounting pad of an engine, replace bobbin part number (P/N) 638005614 with bobbin P/N 638005637 and install a gasket on the feathering pump of that engine in accordance with the Accomplishment Instructions of Fokker Services SB F50-61-025 dated 4 July 2007 or later NAA approved revision.5. Replace bobbin P/N 638005614 with bobbin P/N 638005637 and install a gasket on the feathering pump of that engine in accordance with the Accomplishment Instructions of Fokker Services SB F50-61-025 or later NAA approved revision. |\n\n|             | 6. The replacement of a modified engine with an unmodified (i.e. pre-SBF50-61-024 or pre-SB F50-61-025) engine is no longer authorised.7. Do not install a replacement engine or QEC unit on any aircraft unless it has been modified in accordance with the Accomplishment Instructions of Fokker Services SB F50-61-025 or later NAA approved revisions.After accomplishment of the modification in accordance with Fokker Services SB F50-61-025 on both engines of the aircraft the repetitive visual and detailed inspections in Requirements 1, 2 and 3 of this AD may be discontinued.Note 2: EASA AD 2007-0203 dated 1 August 2007 refers. This AD supersedes CAA Netherlands AD (BLA) 2003-089/2 and BLA 2004-129.                                                                                                                                                                                       |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | 1. Prior to each take-off after the effective date of this AD.2. Before further flight.3. At the intervals specified in the requirement document.4. Before further flight.5. At the next scheduled or unscheduled aircraft maintenance opportunity with sufficient aircraft downtime but no later than 15 August 2009.6. After accomplishment of the modification in accordance with Fokker Services SB F50-61-025.7. From the 15 August 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n|             | This Amendment becomes effective on 26 October 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| Background: | This AD was originally in addition to those requirements previously detailed in AD/F50/85. That AD required replacement of certain parts. This action has not been satisfactory in addressing the unsafe condition. There have been several incidents involving in-flight shut down or aborted take-offs due to oil leakage at the feathering pump. It has been determined that such leakage can be readily identified at the intervals specified in this AD to allow timely rectification of any defects discovered and prevent the unsafe condition from occurring.This amendment supersedes the requirements of AD/F50/85 Amdt 1. This AD now requires in addition to the existing inspections, the fitment of an improved version of the gasket and bobbin, which interface the feathering pump to the engine. Once fitted to both engines the inspections currently required by this AD may be discontinued. |\n\n|     | The original issue of this AD became effective 15 November 2004. AD/F50/85 will be cancelled when this AD becomes effective. |\n| --- | ---------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n23 October 2007","sortOrder":0},{"sectionNumber":"AD/F50/88 Amdt 1","sectionType":"part","heading":"AD/F50/88 Amdt 1","content":"## AD/F50/88 Amdt 1","sortOrder":1},{"sectionNumber":"Power Plant - Feathering pump","sectionType":"part","heading":"Power Plant - Feathering pump","content":"## Power Plant - Feathering pump","sortOrder":2},{"sectionNumber":"13/2007 TX","sectionType":"part","heading":"13/2007 TX","content":"## 13/2007 TX","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"This amendment supersedes AD/F50/85 and expands the prior approach. The original AD required replacement of certain parts; the amended AD adds mandatory repetitive inspections, specific replacement of bobbin P/N 638005614 with P/N 638005637 and gasket fitment (Requirements 2–5), and a prohibition on installing unmodified engines or QECs (Requirements 6–7). Once both engines are modified per the service bulletin, the inspection requirements may be discontinued (Requirement 6; Background)."},"complexity_factors":["Applicability carve-out for engines already modified per Fokker SB SBF50-61-024 Revision 1 (Applicability).","Multiple inspection types and timing: repetitive pre-flight visual checks and separate detailed inspections (Requirement 1; Requirements 2–3; Compliance 1–3).","Pilot-performed inspection allowed only after approved training, shifting some compliance responsibility to operators/pilots (Requirement 1).","Mandatory parts replacement with exact part numbers (bobbin P/N 638005614 → P/N 638005637) and gasket installation (Requirements 4–5).","Prohibition on installing unmodified replacement engines or QEC units, constraining maintenance/parts sourcing (Requirement 6–7; Compliance 7).","Hard deadline for retrofit: next maintenance opportunity but no later than 15 August 2009 (Compliance 5).","Dependence on external technical documents and national authority approvals (Fokker SBs and later NAA approved revisions referenced in Requirements 2–5; Note 2 cites EASA AD 2007-0203).","Inspections may be discontinued only after both engines are modified, creating a stop‑condition contingent on physical work on both engines (Requirement 6; Background).","Administrative effective date and supersession of prior ADs, requiring operators to track regulatory history (Compliance effective date; Background)."],"plain_english_summary":"This airworthiness directive requires operators of Fokker F.27 Mk.50 aeroplanes to carry out pre-flight visual checks and more detailed inspections of the feathering pump area for oil leaks, and to replace a specified bobbin and fit a gasket where leakage is found. Pilots may perform the visual check after approved training. It also bans fitting unmodified replacement engines and allows the inspection regime to stop once both engines have the required modification."},"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":4,"scope_assessment":{"changed":false,"description":"This is an amendment to an existing Airworthiness Directive (AD/F50/88), not a scope expansion. The amendment supersedes related requirements from AD/F50/85 Amdt 1 and consolidates the safety measures into a single directive. The original purpose was addressing oil leakage at feathering pumps; this amendment adds the permanent fix (bobbin/gasket replacement) while maintaining the inspection regime until that fix is applied. This represents a natural evolution of the safety response rather than scope creep."},"complexity_factors":["Multiple cross-references to external technical documents (Fokker Service Bulletins SBF50-61-024, F50-61-023, F50-61-025, and All Operator Message AOF50.037)","Seven distinct numbered requirements with different compliance deadlines and conditions","Nested conditional logic: Requirement 2 only applies if Requirement 1 finds a leak; Requirement 4 only applies if Requirements 2 or 3 find leaks at the mounting pad","Specific part numbers (P/N 638005614 and P/N 638005637) that must be tracked","Interaction with superseded directives (AD/F50/85 and AD/F50/85 Amdt 1) and foreign equivalents (EASA AD 2007-0203, CAA Netherlands ADs)","Dual compliance paths: inspections can be discontinued only after both engines are modified per SB F50-61-025","Pilot-performed maintenance exception requiring 'approved training program' qualification"],"plain_english_summary":"This mandatory CASA Airworthiness Directive affects operators of Fokker F50 (F.27 Mk.50, 0502, 0604) in Australia. It requires trained pilots to visually check specified areas around both engines’ feathering pumps before every take‑off, and mandates mechanic follow‑up inspections and, by August 2009, replacement/modification of parts to fix the leak path. The fix ends repeat checks and forbids reinstalling unmodified engines. It responds to oil leaks that have caused engine shutdowns and aborted take‑offs."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-88-amdt-1-power-plant-feathering-pump","history":"/api/acts/ad-f50-88-amdt-1-power-plant-feathering-pump/history","analysis":"/api/acts/ad-f50-88-amdt-1-power-plant-feathering-pump/analysis","conflicts":"/api/acts/ad-f50-88-amdt-1-power-plant-feathering-pump/conflicts","importantCases":"/api/acts/ad-f50-88-amdt-1-power-plant-feathering-pump/important-cases","documents":"/api/acts/ad-f50-88-amdt-1-power-plant-feathering-pump/documents"}}