{"id":"F2006B09805","name":"AD/F28/71 - Wing to Fuselage Skin Connection","slug":"ad-f28-71-wing-to-fuselage-skin-connection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54727,"registerId":"commonwealth-F2006B09805-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F28/71 - Wing to Fuselage Skin Connection","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 F28 Series Aeroplanes\n\nAD/F28/71 Wing to Fuselage Skin Connection 13/92\n\nApplicability: Serial Numbers 11003 to 11161 inclusive, 11991 and 11992.\n\nRequirement: Reinforce the connecting angles in accordance with RLD AD 91-055, dated 14 June 1991.\n\nNote: Fokker SB F28/53-101 refers.\n\nCompliance: Before 30,000 flights, or 1 June 1997, whichever is the later.\n\nNote: This reinforcement eliminates the need for further inspection in accordance with the F28 Structural Integrity Program, Part 1, item 53-10-14 (AD F28/45).\n\nBackground: Fatigue cracks have been reported in earlier F28 connection angles, which form part of the centre wing to fuselage skin connection. Service experience has shown that these cracks can grow to a large size between inspections. The RLD has therefore determined that modifying these angles should be a mandatory requirement.","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 fatigue issue in a particular aircraft model. The scope remains tightly focused on the original safety concern without expansion into unrelated areas."},"complexity_factors":["Single, specific technical requirement (reinforce connecting angles)","Only one compliance condition (30,000 flights or 1 June 1997, whichever is later)","Limited applicability (specific serial number ranges)","No nested exceptions or conditional logic","Short document with minimal cross-referencing (only references one Dutch directive and one Fokker service bulletin)","No defined terms section"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain **Fokker F28 series aeroplanes** to reinforce the metal angles that connect the wing to the fuselage (the main body of the plane). These angles are structural parts where fatigue cracks have been found.\n\n**Who it affects:**\n- Aircraft with serial numbers 11003 to 11161, plus 11991 and 11992\n- Airlines or operators flying these specific Fokker F28 planes\n\n**What must be done:**\nThe connecting angles must be strengthened following technical instructions from the Dutch aviation authority (RLD AD 91-055). This modification must be completed before the aircraft reaches 30,000 flights or by 1 June 1997 — whichever comes later.\n\n**Why it matters:**\nFatigue cracks had been appearing in these connection points. Because these cracks can grow dangerously large between routine inspections, simply checking for them wasn't enough. The reinforcement is a permanent fix that also cancels out the need for ongoing special inspections of this area.\n\n**Key point:** Once this reinforcement is done, operators no longer need to keep inspecting this specific spot under the previous safety order (AD F28/45)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This directive replaces the prior recurring inspection requirement (F28 Structural Integrity Program, Part 1, item 53-10-14) for the listed aeroplanes with a mandatory structural reinforcement (Requirement; Note). The Background explains the change responds to observed fatigue cracks that could grow between inspections, and the AD makes the modification mandatory for the specified serial numbers by the stated flight-hour/date deadline (Background; Compliance)."},"complexity_factors":["Limited and specific applicability to a defined set of serial numbers (Applicability)","Single, well-defined mandated action (reinforce connecting angles) referenced to an external technical document (RLD AD 91-055) (Requirement)","Conditional deadline expressed as ‘before 30,000 flights or 1 June 1997, whichever is later’, requiring tracking of flight counts and calendar dates (Compliance)","Interaction with existing maintenance regime: reinforcement removes a particular recurring inspection obligation (Note), creating an exchange between a one-off modification and ongoing inspections","Technical work likely requires certified maintenance organisations and parts, adding operational scheduling and supply considerations (implicit in Requirement and Background)"],"plain_english_summary":"What this instrument does (mechanically)\n\n- Mandates a physical modification: operators of certain Fokker F28 aeroplanes must reinforce the connecting angles that join the centre wing to the fuselage skin. The reinforcement must be carried out in accordance with RLD AD 91-055 (Requirement).\n- Identifies which aeroplanes are covered: serial numbers 11003 to 11161 inclusive, and serials 11991 and 11992 (Applicability).\n- Sets a deadline: the reinforcement must be completed before each affected aeroplane reaches 30,000 flights, or by 1 June 1997, whichever date is later (Compliance).\n- Removes a continuing inspection obligation for affected aeroplanes once the reinforcement is fitted: the reinforcement eliminates the need for the inspection described in the F28 Structural Integrity Program, Part 1, item 53-10-14 (Note).\n\nWhy the regulator requires this (official rationale, attributed)\n\n- The Background states that fatigue cracks were reported in earlier connection angles that form part of the centre wing-to-fuselage skin connection and that these cracks can grow to a large size between inspections. The RLD determined that modifying these angles should be mandatory to address that service experience (Background).\n\nOperational and economic effects, stated plainly with source pointers\n\n- Who pays: aircraft owners/operators of the listed serial numbers are responsible for arranging and funding the reinforcement work (Applicability; Requirement). The AD does not specify funding mechanisms or cost amounts.\n- Who decides and enforces: the Civil Aviation Safety Authority issued this airworthiness directive as a mandatory requirement within the Schedule of Airworthiness Directives; compliance is required by the dates stated (header; Compliance).\n- Compliance burden: operators must schedule and carry out a structural modification per the referenced RLD AD 91-055 (Requirement). This entails parts, labour, engineering and calendar/flight-hour planning; those specific costs and downtimes are not quantified in the text (Requirement).\n- Net change in recurring workload: after the reinforcement is installed, the affected aeroplane no longer requires the specific recurring inspection in the Structural Integrity Program (Part 1, item 53-10-14), so operators will cease that inspection for reinforced aeroplanes (Note). That reduces future inspection labour/time for those aeroplanes but substitutes a one-off modification cost (Note; Compliance).\n- Implementation dependencies and risks: the AD makes compliance conditional on following an external technical document (RLD AD 91-055). Operators must obtain and correctly implement that technical procedure to satisfy the AD (Requirement). The Background indicates the change responds to observed in-service crack growth between inspections, so timely and correct modification is necessary to realise the intended safety effect (Background).\n- Effects on the maintenance market and choice: the AD creates demand for the specified reinforcement work for the listed fleet. Maintenance organisations that can perform the modification may competitively bid for that work; operators may choose their maintenance provider subject to appropriate approvals and the technical requirements (Applicability; Requirement).\n\nTrade-offs and incentives (mechanics, not judgement)\n\n- The AD substitutes a mandatory structural modification for repeated inspections for the affected serial numbers: this creates an upfront cost and operational disruption for operators in exchange for eliminating a recurring inspection obligation (Requirement; Note).\n- Incentives for operators: operators face a clear compliance incentive — fit the reinforcement by the specified flight-hours/date — to avoid non-compliance with the directive. Once fitted, operators avoid the recurring inspection named in the AD, which reduces ongoing inspection costs for those aeroplanes (Compliance; Note).\n- Administrative discretion and openness: the AD refers operators to RLD AD 91-055 for the technical reinforcement method (Requirement). The text does not itself set engineering detail or alternate compliance methods; any variance would depend on the procedures or approvals referenced in that external document (Requirement).\n\nRelevant source passages cited: Applicability; Requirement (RLD AD 91-055); Compliance (deadline); Note (inspection elimination); Background (reported fatigue cracks and rationale)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f28-71-wing-to-fuselage-skin-connection","history":"/api/acts/ad-f28-71-wing-to-fuselage-skin-connection/history","analysis":"/api/acts/ad-f28-71-wing-to-fuselage-skin-connection/analysis","conflicts":"/api/acts/ad-f28-71-wing-to-fuselage-skin-connection/conflicts","importantCases":"/api/acts/ad-f28-71-wing-to-fuselage-skin-connection/important-cases","documents":"/api/acts/ad-f28-71-wing-to-fuselage-skin-connection/documents"}}