{"id":"F2006B09690","name":"AD/F27/123 - Flight Compartment Window Frames","slug":"ad-f27-123-flight-compartment-window-frames","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115843,"registerId":"commonwealth-F2006B09690-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/123 - Flight Compartment Window Frames","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/F27/123 Flight Compartment Window Frames 10/91\n\nApplicability: Serial numbers 10102, 10105 to 10684 inclusive, 10686, 10687, and 10689 to 10692 inclusive, which have been modified in accordance with Fokker Service Bulletin F27/21-30.\n\nRequirement: Inspect in accordance with the Technical Requirements of RLD AD 89-125, dated 13 October 1989.\n\nNote: Fokker Service Bulletin F27/53-109, dated 10 October 1989 refers.\n\nCompliance: (i) On aircraft serial numbers 10561 to 10684 inclusive, 10686, 10687, and 10689 to 10692 inclusive; upon accumulating 20 000 pressurisation cycles, or before\n\n26 December 1991, whichever is the later, or\n\n(ii) On aircraft serial numbers 10102, and 10105 to 10560 inclusive: upon accumulating 30 000 pressurisation cycles, or before 26 December 1991, whichever is the later.\n\nBackground: Full-scale fatigue tests on the similar F50 forward fuselage have indicated that cracks may occur in the F27 window post assemblies, particularly the side frames and frame corners. This AD calls for a one-time inspection. Incorporation of Repair Schemes I to V inclusive, in accordance with Fokker Service Bulletin F27/53-110, constitutes compliance with this AD.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD confines action to specific serial numbers modified per Fokker Service Bulletin F27/21-30 and prescribes a one-time inspection or incorporation of specified repair schemes to address fatigue cracks identified in F50 tests (Applicability; Background). It does not expand applicability beyond those modified aircraft or add recurring inspections; it enforces inspection/repair options consistent with the stated safety objective."},"complexity_factors":["Precise serial-number applicability narrows and complicates identification of affected aircraft (Applicability).","Two different pressurisation-cycle thresholds (20,000 v. 30,000) tied to serial ranges create operational tracking requirements (Compliance (i)/(ii)).","Cross-reference to foreign airworthiness directive (RLD AD 89-125) delegates technical detail to another document (Requirement).","Multiple Fokker service bulletins are referenced for modification, inspection and repair details, requiring operators to consult several external documents (Applicability; Note; Background).","Alternative compliance via incorporation of Repair Schemes I–V requires implementation and recordkeeping of structural repairs (Background).","Timing rule 'whichever is the later' adds date-or-cycle decision logic for compliance scheduling (Compliance).","Technical subject matter (fatigue cracking from pressurisation cycles) requires specialised inspection methods and interpretation."],"plain_english_summary":"Mandates one‑time inspections of flight‑compartment window frames on specified Fokker F27 aeroplanes and allows approved repair schemes as an alternative means of compliance. Operators must follow the technical requirements of RLD AD 89‑125 (as referenced) and the Fokker service bulletins.\n\nApplies only to listed serial numbers modified per Fokker Service Bulletin F27/21‑30; inspections are required by accumulation of 20,000 or 30,000 pressurisation cycles (depending on serial number) or by 26 December 1991, whichever is later. Purpose stated: detect fatigue cracks indicated by F50 tests."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete airworthiness directive with a narrow, specific scope (inspection of window frames on specific F27 aircraft). It has not expanded beyond its original safety purpose."},"complexity_factors":["Multiple serial number ranges with different compliance thresholds (20,000 vs 30,000 pressurisation cycles)","Cross-reference to external technical documents (RLD AD 89-125 and Fokker Service Bulletins F27/21-30, F27/53-109, and F27/53-110)","Conditional compliance dates ('whichever is the later') creating a dual-threshold test","Specific applicability filter requiring prior modification per Service Bulletin F27/21-30"],"plain_english_summary":"This is a one‑time safety inspection order requiring owners/operators of specified Fokker F27 aeroplanes (those modified per Fokker SB F27/21‑30) to inspect cockpit window frames for fatigue cracks. It responds to F50 testing that found corner and side‑post cracking that could threaten structural integrity.\n\nCompliance: for serials 10561+ inspect after 20,000 pressurisation cycles or by 26 Dec 1991 (whichever is later); for serials 10102 and 10105–10560 inspect after 30,000 cycles or by 26 Dec 1991. Follow RLD AD 89‑125 or Fokker SB F27/53‑110 repairs."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-123-flight-compartment-window-frames","history":"/api/acts/ad-f27-123-flight-compartment-window-frames/history","analysis":"/api/acts/ad-f27-123-flight-compartment-window-frames/analysis","conflicts":"/api/acts/ad-f27-123-flight-compartment-window-frames/conflicts","importantCases":"/api/acts/ad-f27-123-flight-compartment-window-frames/important-cases","documents":"/api/acts/ad-f27-123-flight-compartment-window-frames/documents"}}