{"id":"F2006B09695","name":"AD/F27/128 - Outer Flap Lower Skin and Rib","slug":"ad-f27-128-outer-flap-lower-skin-and-rib","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115852,"registerId":"commonwealth-F2006B09695-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/128 - Outer Flap Lower Skin and Rib","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Fokker F27 Series Aeroplanes\n\n \n\nAD/F27/128 Outer Flap Lower Skin and Rib 2/92\n\nApplicability: All model F27, all serial numbers.\n\n \n\nRequirement: Inspect the outer flap lower skin and rib in accordance with the technical requirements of Fokker SB F27/57-67.\n\n \n\nNote: RLD AD 91-122 refers.\n\n \n\nCompliance: As specified in the Requirement document with a revised effective date of 3 February 1992 (a four month extension).\n\n \n\nBackground: Country of origin AD. Some operators are reported to have found cracks at various locations in the lower skin and rib at STA.580 of the outer flaps. As these cracks are likely to exist on other aircraft of the same type, this AD requires inspection of the affected areas and provides for a repair if necessary.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural issue on a specific aircraft type. It has not expanded beyond its original purpose of mandating inspection for fatigue cracks in the outer flap assembly."},"complexity_factors":["Single, specific mechanical component addressed (outer flap lower skin and rib)","No defined terms section — uses plain technical language","Single cross-reference to external technical document (Fokker SB F27/57-67)","No conditional logic or nested exceptions","Very short document (approximately 150 words of substantive content)","Straightforward applicability (all model F27, all serial numbers)"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:** It requires owners and operators of Fokker F27 aircraft to inspect a specific part of the plane — the outer flap lower skin and rib (a structural component of the wing flaps). The inspection must follow technical instructions laid out in a Fokker Service Bulletin (SB F27/57-67).\n\n**Why it matters:** Cracks had been found in this area on some F27 aircraft. Because these cracks could weaken the aircraft structure and potentially affect flight safety, the directive mandates checks across all F27 models to catch problems before they become dangerous. If cracks are found, repairs are required.\n\n**Who it affects:** Anyone who owns, operates, or maintains Fokker F27 aircraft in Australia — all models and serial numbers are covered.\n\n**Key details:**\n- **Compliance deadline:** The inspection must be done by the date specified in the Fokker Service Bulletin, with a four-month extension to 3 February 1992\n- **Origin:** This mirrors a Dutch aviation safety directive (RLD AD 91-122), as the Fokker F27 is a Dutch-designed aircraft\n- **Purpose:** Prevent structural failure by catching fatigue cracks early"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Applicability remains all F27 models/serials, but the compliance timing was amended: the effective date was revised to 3 February 1992 (a four‑month extension). The inspection and repair requirement itself is unchanged (Applicability; Requirement; Compliance)."},"complexity_factors":["Narrow technical focus but requires physical inspections and possible structural repairs across the entire fleet (Applicability; Requirement; Background).","Mandates compliance with an external manufacturer Service Bulletin (Fokker SB F27/57-67), creating reliance on that document for procedures and thresholds (Requirement).","Cross-references other directives (country of origin AD and RLD AD 91-122), increasing traceability and coordination needs (Note; Background).","Revised compliance date (effective 3 Feb 1992) changes scheduling and operational planning for operators (Compliance).","Operators bear direct costs and operational downtime for inspections and repairs; extent of repairs depends on inspection findings (Requirement; Background).","Limited procedural detail in the AD itself — implementers must consult the Service Bulletin for inspection methods and repair standards (Requirement)."],"plain_english_summary":"Requires inspection of the outer flap lower skin and rib on all Fokker F27 aircraft according to Fokker Service Bulletin F27/57-67; operators must carry out repairs if defects are found (Requirement). The AD follows a country‑of‑origin directive after reported cracks at STA.580 and sets a revised compliance effective date of 3 February 1992 (Background; Compliance). Operators pay for inspections and any repairs and must follow the specified service bulletin."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-128-outer-flap-lower-skin-and-rib","history":"/api/acts/ad-f27-128-outer-flap-lower-skin-and-rib/history","analysis":"/api/acts/ad-f27-128-outer-flap-lower-skin-and-rib/analysis","conflicts":"/api/acts/ad-f27-128-outer-flap-lower-skin-and-rib/conflicts","importantCases":"/api/acts/ad-f27-128-outer-flap-lower-skin-and-rib/important-cases","documents":"/api/acts/ad-f27-128-outer-flap-lower-skin-and-rib/documents"}}