{"id":"F2006B09706","name":"AD/F27/139 - Outer Wing Rib-to-Stringer Connections","slug":"ad-f27-139-outer-wing-rib-to-stringer-connections","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115874,"registerId":"commonwealth-F2006B09706-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/139 - Outer Wing Rib-to-Stringer Connections","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/F27/139 Outer Wing Rib-to-Stringer Connections 3/95\n\nApplicability: F27 aircraft, S/N 10653 to 10692 inclusive, without Service Bulletins F27/57-68 Part 1 and F27/57-70 Part 1 incorporated.\n\nRequirement: 1. Visually inspect the wing upper and lower skin rib-to-stringer connections at wing stations 11260, 11860, 12660 and 13460 for loose and missing rivets. Inspect in accordance with Fokker Service Bulletin (SB) F27/57-74 Part 2.\n\n2. Replace P/N MS20600AD4W2 rivets at the wing upper and lower skin rib-to- stringer connections with P/N CR3553P4 rivets. Replace rivets at wing stations 11260, 11860, 12660 and 13460 in accordance with Fokker SB F27/57-74 Part 1.\n\nNote: Netherlands RLD AD BLA94-148(A) refers.\n\nCompliance: 1. Inspect before 10 000 flights or before 2 May 1995, whichever occurs later.\n\n2. Replace rivets before 10 000 flights or before 1 December 1995, whichever occurs later.\n\nBackground: Several F27 operators have reported missing rivets at the rib-to-stringer connections. Investigation revealed that lower strength MS2060AD4W2 rivets had been installed in production on certain serial number aircraft.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted airworthiness directive addressing a specific manufacturing defect on a limited range of aircraft. It has not expanded beyond its original purpose of ensuring structural integrity of Fokker F27 wing connections."},"complexity_factors":["Single, specific technical subject matter (rivet replacement on one aircraft type)","Only 4 defined serial number range and 4 specific wing station locations","Two straightforward compliance actions (inspect and replace) with clear deadlines","Minimal cross-referencing (only to two Fokker service bulletins and one Netherlands aviation authority document)","No nested exceptions or conditional logic — applicability is a simple binary (specific serial numbers without specific service bulletins incorporated)","Document is extremely short (under 300 words)"],"plain_english_summary":"Owners/operators of Fokker F27 serials 10653–10692 must inspect outer wing rib-to-stringer connections at four locations for loose or missing rivets, and replace specified rivets with stronger ones if required — but only if two factory service bulletins haven’t already been complied with.  \n\nThis CASA Airworthiness Directive responds to reports of inadvertently installed weaker rivets that risk wing structural failure; it sets inspection and replacement deadlines tied to flight cycles or specified 1995 dates."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD maintains a focused scope: it applies only to specified serial-number F27s lacking certain service-bulletin incorporations and requires inspection and rivet replacement to address discovered lower-strength rivets (Applicability; Requirement; Background). It does not broaden applicability beyond those aircraft or add new regulatory powers; it prescribes corrective maintenance and compliance timing only."},"complexity_factors":["Narrow applicability: limited to F27 S/N 10653–10692 and only if certain SBs are not incorporated (Applicability) — requires records checks.","Technical maintenance task: visual inspections of upper and lower skin rib-to-stringer connections at specified wing stations per Fokker SB F27/57-74 Part 2 (Requirement 1) — needs access and maintenance skill.","Parts replacement: swap P/N MS20600AD4W2 rivets for P/N CR3553P4 per SB F27/57-74 Part 1 (Requirement 2) — requires part procurement and approved installation.","Scheduling constraints: compliance tied to flight counts or fixed dates (Compliance) — creates operational planning burden.","Procedural dependency: mandates following manufacturer service bulletins for inspection and replacement procedures (Requirements 1–2) — external-document reliance.","Regulatory cross-reference: notes Netherlands RLD AD BLA94-148(A) (Note) — may require coordination with foreign airworthiness findings."],"plain_english_summary":"This Airworthiness Directive orders operators of Fokker F27 aircraft S/N 10653–10692 (unless they’ve already incorporated specified Fokker service bulletins) to inspect wing rib-to-stringer connections for loose or missing rivets and to replace lower-strength MS20600AD4W2 rivets with CR3553P4 rivets (Requirements 1–2). Operators pay for inspections, parts and work, must follow Fokker SB F27/57-74 Parts 1–2, and meet the flight-count or calendar deadlines in the AD (Applicability; Compliance; Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-139-outer-wing-rib-to-stringer-connections","history":"/api/acts/ad-f27-139-outer-wing-rib-to-stringer-connections/history","analysis":"/api/acts/ad-f27-139-outer-wing-rib-to-stringer-connections/analysis","conflicts":"/api/acts/ad-f27-139-outer-wing-rib-to-stringer-connections/conflicts","importantCases":"/api/acts/ad-f27-139-outer-wing-rib-to-stringer-connections/important-cases","documents":"/api/acts/ad-f27-139-outer-wing-rib-to-stringer-connections/documents"}}