{"id":"F2006B09660","name":"AD/F100/6 - Rib/Auxiliary Spar Attachment Rivets","slug":"ad-f100-6-rib-auxiliary-spar-attachment-rivets","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115784,"registerId":"commonwealth-F2006B09660-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F100/6 - Rib/Auxiliary Spar Attachment Rivets","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 F100 (F28 Mk 100) Series Aeroplanes\n\nAD/F100/6 Rib/Auxiliary Spar Attachment Rivets 4/99\n\nApplicability: F.28 MK.0100 aircraft serial numbers, 11244 through 11256, 11259, 11260 and\n\n11268 through 11278.\n\nRequirement: Replace affected aluminium alloy rivets with two nickel-copper alloy rivets and four hilok bolts in accordance with Fokker Service Bulletin (SB) F100-57-017 dated 12 September 1991.\n\nNote: RLD BLA 91-107 refers.\n\nCompliance: Unless previously accomplished, before accumulating 18,000 flight cycles since new or before 50 flight cycles after 22 April 1999, whichever occurs later.\n\nThis Airworthiness Directive becomes effective on 22 April 1999.\n\nBackground: During fatigue tests on the F.28 Mk.0100, six broken rivets were found. These rivets are located at the rib-to-auxiliary-spar attachment at wing STA.10110. This AD requires a modification to strengthen this attachment.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD’s operative requirements match the stated purpose in the background: to strengthen the rib‑to‑auxiliary‑spar attachment at wing STA.10110 after broken rivets were found during fatigue testing. The instrument applies only to the specifically listed serial numbers and mandates a single corrective modification in accordance with the referenced Fokker Service Bulletin, so the scope as written aligns with that original, technical intent (Applicability; Requirement; Background)."},"complexity_factors":["Narrow applicability by specific serial numbers (Applicability) — reduces scope but requires accurate aircraft identification","Single, technically specific modification mandated (replace aluminium rivets with two nickel‑copper rivets and four hilok bolts) — technical but procedurally simple (Requirement)","Mandatory reference to a manufacturer Service Bulletin for method and parts creates dependency on that document for execution (Requirement)","Time‑based compliance that uses an either/or condition (18,000 flight cycles since new OR within 50 flight cycles after 22 April 1999, whichever occurs later) — requires operators to monitor flight cycles accurately (Compliance)","Safety‑critical nature of the affected structure (rib‑to‑auxiliary‑spar attachment) increases operational importance though not legal complexity (Background)"],"plain_english_summary":"What this rule does mechanically\n\n- It requires a physical modification on a specific set of Fokker F100 (F28 Mk 100) aeroplanes (listed by serial number in the “Applicability” section) to change the fastenings at a particular wing attachment point. (Applicability; Requirement)\n- The work specified is: replace the affected aluminium alloy rivets with two nickel‑copper alloy rivets and four hilok bolts, carried out in accordance with Fokker Service Bulletin F100‑57‑017 dated 12 September 1991. (Requirement)\n- The modification must be done by the deadline in the AD: before the aeroplane accumulates 18,000 flight cycles since new or within 50 flight cycles after 22 April 1999, whichever is later. The AD became effective on 22 April 1999. (Compliance; Effective date)\n\nWhy the rule exists (official rationale)\n\n- The background provided says that fatigue tests discovered six broken rivets at the rib‑to‑auxiliary‑spar attachment at wing station STA.10110. The AD’s stated purpose is to strengthen that attachment by requiring the replacement described above. (Background; Requirement)\n\nWho pays and who decides\n\n- The operator/owner of each affected aeroplane is required to have the modification carried out on that aeroplane (the AD imposes the action and the compliance timing). The AD specifies the method to be used by referencing the manufacturer’s Service Bulletin, so the required technique and parts are set by that SB. (Requirement)\n\nCompliance burden and implementation mechanics\n\n- Operators must: identify whether their aircraft serial number is within the listed set (Applicability); source the specified nickel‑copper rivets and hilok bolts and follow the procedures in Fokker SB F100‑57‑017; and schedule the work within the AD’s flight‑cycle deadline. (Applicability; Requirement; Compliance)\n- The AD does not specify who must perform the work (for example, a type‑rated maintenance organisation vs. the operator’s own engineers); it prescribes the parts and the Service Bulletin as the method. That places practical reliance on whoever is engaged to carry out maintenance to follow the SB. (Requirement)\n\nTrade‑offs, incentives and risks (mechanical, logistical and economic)\n\n- The directive creates a near‑term compliance cost for owners/operators of the affected serial‑numbered aircraft in the form of parts, labour and scheduling (Compliance; Requirement). The AD does not provide funding or exemptions. (Requirement; Compliance)\n- The AD reduces technical discretion about how to fix the problem by mandating the manufacturer’s Service Bulletin as the required procedure, which channels operators to use the specified parts and steps. (Requirement)\n- Implementation risks that follow from the AD’s text include availability of the specified parts and the need to schedule the modification within the flight‑cycle limit; the AD does not state allowances for parts shortages or alternative procedures. (Requirement; Compliance)\n\nNet mechanical effect\n\n- Aircraft in the listed serial‑number range must have the specified rivets and bolts installed at the rib‑to‑auxiliary‑spar attachment at wing STA.10110 by the stated flight‑cycle deadline, with the aim (per the AD’s background) of preventing failures like the broken rivets found in fatigue testing. (Applicability; Requirement; Background)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope — a specific structural repair for identified aircraft. It has not expanded beyond its original safety purpose."},"complexity_factors":["Single, specific technical requirement with clear replacement instructions","Limited applicability to exactly 17 identified aircraft by serial number","Straightforward compliance deadline with simple 'whichever occurs later' logic","No defined terms section or complex interpretive provisions","Single cross-reference to a Fokker Service Bulletin and one related document (RLD BLA 91-107)","No conditional exceptions, exemptions, or nested provisions"],"plain_english_summary":"This is a **safety order for specific Fokker F100 aircraft**.\n\n**What it does:**\nThe Civil Aviation Safety Authority (CASA) has issued a mandatory repair order for 17 specific Fokker F100 aeroplanes (serial numbers 11244-11256, 11259, 11260, and 11268-11278). These planes must have certain rivets in their wings replaced with stronger fasteners.\n\n**The problem:**\nDuring fatigue testing, engineers found six broken rivets where the wing rib connects to the auxiliary spar (a structural beam in the wing). Broken rivets in this location could weaken the wing structure.\n\n**What must be done:**\n- Remove specific aluminium alloy rivets\n- Install two nickel-copper alloy rivets and four \"hilok bolts\" (a type of high-strength fastener) instead\n- Follow the exact instructions in Fokker Service Bulletin F100-57-017\n\n**When it must be done:**\nBefore the aircraft reaches 18,000 flight cycles (takeoff-landing cycles) OR within 50 flights after 22 April 1999 — whichever comes later.\n\n**Who it affects:**\nOwners and operators of these specific 17 Fokker F100 aircraft registered in Australia.\n\n**Why it matters:**\nThis prevents potential structural failure in the wing. Airworthiness Directives are legally binding — operators cannot fly these aircraft without completing this modification."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f100-6-rib-auxiliary-spar-attachment-rivets","history":"/api/acts/ad-f100-6-rib-auxiliary-spar-attachment-rivets/history","analysis":"/api/acts/ad-f100-6-rib-auxiliary-spar-attachment-rivets/analysis","conflicts":"/api/acts/ad-f100-6-rib-auxiliary-spar-attachment-rivets/conflicts","importantCases":"/api/acts/ad-f100-6-rib-auxiliary-spar-attachment-rivets/important-cases","documents":"/api/acts/ad-f100-6-rib-auxiliary-spar-attachment-rivets/documents"}}