{"id":"F2006B09703","name":"AD/F27/136 - Outer Flap Centre Hinge","slug":"ad-f27-136-outer-flap-centre-hinge","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115868,"registerId":"commonwealth-F2006B09703-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/136 - Outer Flap Centre Hinge","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)  \nFokker F27 Series Aeroplanes\n\nAD/F27/136 Outer Flap Centre Hinge 9/94\n\nApplicability: Fokker Model F27 aircraft, serial numbers 10102 and 10105 to 10240 inclusive.\n\nRequirement: Conduct a High Frequency Eddy Current (HFEC) inspection of the outer flap centre hinge bearing bore, on both wings, in accordance with Part 1 of Fokker Service Bulletin (SB) F27/57-66. Repair flap centre hinge fittings whether cracked or not.\n\nNote: RLD AD 91-129 refers.\n\nCompliance: 1. Hinge fittings not modified in accordance with Fokker SB F27/57-22.\n\n    Inspect per Fokker SB F27/57-66 part 1\n\n    (i) If the aircraft has exceeded 72000 flights, then inspect within 1000 flights from 18 August 1994 or before 1 February 1995, whichever occurs first.\n\n    b. Repair per Fokker SB F27/57-66 part 2\n\n    (i) Within 300 flights if the crack length inside the bore is less than 5mm and no cracking exists on the faces of the bore,\n\n    (ii) Before further flight if cracking exceeds either of the limitations of para\n\n1.b. (i).\n\n    (iii) Within 2800 flights or two years if no cracks are found.\n\n    2. Hinge fittings modified in accordance with Fokker SB F27/57-22.\n\n    Inspect per Fokker SB F27/57-66 part 1\n\n    (i) If the aircraft has exceeded 55000 flights, then inspect within 1000 flights from 18 August 1994 or before 1 February 1995, whichever occurs first.\n\n    b. Repair per Fokker SB F27/57-66 part 2\n\n    (i) Within 300 flights if the crack length inside the bore is less than 5mm and no cracking exists on the faces of the bore,\n\n    (ii) Before further flight if cracking exceeds either of the limitations of para 2.b.(i), or if a crack inside the bore is located near the grease nipple bore.\n\n    (iii) Within 2800 flights or two years if no cracks are found.\n\nNote: Outer flap centre hinges which have not yet reached the newly established retirement lives of 72000 or 55000 flights are covered by the F27 Structural Integrity Program, Part 1, Item 57-50-02 (AD/F27/103 refers).\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nBackground: Analysis of the service loads spectrum has shown that the loads on the outer flap centre hinge are higher than originally expected. This has resulted in a reduction in the fatigue life for the early style hinge fittings. This Directive requires inspection and repair to maintain airworthiness integrity on affected aircraft which now find themselves in excess of the new hinge fitting retirement lives.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive remains tightly focused on its original purpose: addressing a specific structural fatigue issue in Fokker F27 aircraft outer flap centre hinges. The scope has not expanded beyond the specific serial number range and component identified in the original safety concern."},"complexity_factors":["Multiple conditional pathways based on modification status (modified vs unmodified hinges)","Nested time-based compliance deadlines (flight counts vs calendar dates)","Cross-references to external technical documents (Fokker Service Bulletins F27/57-66, F27/57-22, and AD/F27/103)","Technical aviation terminology requiring specialized knowledge (HFEC, fatigue life, retirement lives)","Dual threshold system (55,000 vs 72,000 flights) creating parallel but distinct compliance regimes","Hierarchical numbering system (1.b.(i), 2.b.(ii)) with conditional logic ('if...then', 'whichever occurs first')","Reference to foreign regulatory document (RLD AD 91-129 from Netherlands aviation authority)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of specified Fokker F27s to perform High Frequency Eddy Current inspections of the outer flap centre hinge and to repair any cracking found. Repair timing is immediate for serious cracks, sooner for minor cracks, or later if no cracks are detected, with thresholds varying by hinge modification history and flight cycles.\n\nIt prevents hinge fatigue and potential flap/wing structural failure, protecting flight safety."},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Scope was effectively changed: the AD responds to a reassessment that reduced hinge fitting fatigue lives and therefore applies mandatory inspection and repair requirements to aircraft now exceeding the newly established retirement lives (72,000 flights for unmodified fittings; 55,000 for fittings modified per SB F27/57-22). This extends enforceable surveillance/repair obligations to airframes that were previously within earlier retirement limits."},"complexity_factors":["Applicability limited to specific serial-number range (serials 10102 and 10105–10240) which requires operators to verify affected fleet status.","Different inspection triggers and retirement thresholds depending on modification status (unmodified: 72,000 flights; modified per SB F27/57-22: 55,000 flights).","Multiple compliance windows expressed as flight-count limits, an absolute calendar/date option (inspect within 1,000 flights from 18 Aug 1994 or before 1 Feb 1995), and longer periodic intervals (within 2,800 flights or two years if no cracks).","Conditional repair requirements tied to crack characteristics and location (repair within 300 flights if bore crack <5 mm and no face cracking; before further flight if cracking exceeds limits or is near grease nipple bore).","Mandates a specific non‑destructive test method (HFEC) and cross-references external technical documents (Fokker SB F27/57-66 parts 1 & 2 and SB F27/57-22), increasing reliance on external service bulletin content for execution.","References to other directives and programs (RLD AD 91-129; AD/F27/103; F27 Structural Integrity Program) create traceability and potential overlap with existing compliance obligations.","Operational impact implied by 'before further flight' and staged deadlines (possible unplanned grounding, logistics for HFEC inspection and repair) increasing compliance burden."],"plain_english_summary":"Requires High Frequency Eddy Current inspections of the outer‑flap centre‑hinge bearing bores on specified Fokker F27 serial numbers and mandates repair of hinge fittings per Fokker Service Bulletin F27/57‑66. It differentiates aircraft by whether they were modified under SB F27/57‑22 and by accumulated flight counts, setting staged inspection and repair deadlines. The rule affects operators of the listed aircraft, who must pay for inspections, repairs and any out‑of‑service time to comply with the newly established hinge retirement lives."},"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-f27-136-outer-flap-centre-hinge","history":"/api/acts/ad-f27-136-outer-flap-centre-hinge/history","analysis":"/api/acts/ad-f27-136-outer-flap-centre-hinge/analysis","conflicts":"/api/acts/ad-f27-136-outer-flap-centre-hinge/conflicts","importantCases":"/api/acts/ad-f27-136-outer-flap-centre-hinge/important-cases","documents":"/api/acts/ad-f27-136-outer-flap-centre-hinge/documents"}}