{"id":"F2006B09654","name":"AD/F100/51 - Vertical Stabiliser Torsion Box - 2","slug":"ad-f100-51-vertical-stabiliser-torsion-box-2","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115773,"registerId":"commonwealth-F2006B09654-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.002.png)![](image.001.png)AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nFokker F100 (F28 Mk 100) Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/F100/51 Vertical Stabiliser Torsion B","sectionType":"part","heading":"AD/F100/51 Vertical Stabiliser Torsion Box - 2 7/2002","content":"# AD/F100/51 Vertical Stabiliser Torsion Box \\- 2 7/2002\n\nApplicability: Model F.28 Mk.0100 aircraft, serial numbers 11244 through 11460, 11463 through 11469, 11471, 11474 through 11483, 11489, 11490, 11491, 11497, 11498, 11499,\n\n11501, 11502, 11504, 11506, 11507, 11512 through 11515, 11517, and 11520.\n\nRequirement: Cold expand the 12 hi- lok bolt holes at the Rib 5.0 position of the vertical stabiliser torsion box, in accordance with Parts 1, 2, and 3 of the Accomplishment Instructions, as applicable, of Fokker Service Bulletin (SB) F100-55-023, dated 3 January 1995.\n\nNote: Netherlands CAA AD 1995-017 refers.\n\nCompliance: 1. For aircraft which have already been in-service modified to post SB F100-55- 018-configuration:\n\nBefore accumulating 10,000 flight cycles since the accomplishment of the modification in accordance with Fokker SB F100-55-018 (as required by AD 93- 069); or,\n\n    2. For aircraft which are still in pre-SB F100-55-018-configuration:\n\nConcurrent with the accomplishment of the modification in accordance with Fokker SB F100-55-018 (as required by AD 93-069); or,\n\n    3. For aircraft which have had SB F100-55-018 factory incorporated: Before accumulating 10,000 flight cycles since new.\n\nThis Airworthiness Directive becomes effective on 11 July 2002.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive specifies corrective work for a defined set of serial-numbered aircraft and sets conditional deadlines tied to prior modification status or flight cycles. The text does not indicate an expansion or narrowing of applicability beyond the listed aircraft or a change from the stated corrective action."},"complexity_factors":["Technical procedure required: cold expanding 12 hi‑lok bolt holes at Rib 5.0 of the vertical stabiliser torsion box (Requirement).","Work must follow multiple Parts (1–3) of Fokker SB F100‑55‑023, creating dependency on external technical instructions (Requirement).","Applicability limited to a long, specific list of serial numbers, requiring operators to check serial inclusion (Applicability).","Conditional compliance paths tied to prior modification status (SB F100‑55‑018) and accumulated flight cycles, producing multiple deadlines and record checks (Compliance).","Cross-references to earlier ADs and foreign CAA AD (AD 93‑069; Netherlands CAA AD 1995‑017) add historical compliance context that operators must reconcile (Note/Compliance).","Administrative enforcement through CASA under CAR 1998 subregulation 39.1(1) — operators must schedule, fund and document the corrective action (intro/Compliance)."],"plain_english_summary":"This Airworthiness Directive requires operators of specific Fokker F.28 Mk 100 (F100) aircraft (listed by serial number) to cold-expand 12 hi‑lok bolt holes at Rib 5.0 of the vertical stabiliser torsion box, following Parts 1–3 of Fokker Service Bulletin F100‑55‑023. Compliance deadlines depend on whether the aircraft already has the SB F100‑55‑018 modification, was factory‑built with it, or is having it done now; operators must arrange and pay for the work within the flight‑cycle/timing windows stated."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — a specific structural repair on specific aircraft. It does not expand beyond its original safety purpose."},"complexity_factors":["Multiple conditional compliance pathways based on aircraft modification history (3 distinct scenarios)","Technical aviation terminology requiring specialized knowledge (e.g., 'cold expand', 'hi-lok bolt holes', 'torsion box', 'flight cycles')","Cross-reference to external technical document (Fokker Service Bulletin F100-55-023) which is not reproduced in the AD","Reference to prior regulatory action (AD 93-069) and foreign aviation authority document (Netherlands CAA AD 1995-017)","Specific serial number applicability list (32 individual serial numbers or ranges)"],"plain_english_summary":"This Airworthiness Directive mandates a specific repair on the vertical stabiliser torsion box of certain Fokker F100 serial-numbered aircraft: cold‑expanding 12 bolt holes per Fokker Service Bulletin F100‑55‑023. It affects owners/operators and maintenance personnel and is intended to prevent fatigue cracking around bolt holes that could compromise structural integrity. Compliance timing varies by whether the aircraft was previously modified or entered service with the factory modification, with actions required within defined flight‑cycle limits."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-f100-51-vertical-stabiliser-torsion-box-2","history":"/api/acts/ad-f100-51-vertical-stabiliser-torsion-box-2/history","analysis":"/api/acts/ad-f100-51-vertical-stabiliser-torsion-box-2/analysis","conflicts":"/api/acts/ad-f100-51-vertical-stabiliser-torsion-box-2/conflicts","importantCases":"/api/acts/ad-f100-51-vertical-stabiliser-torsion-box-2/important-cases","documents":"/api/acts/ad-f100-51-vertical-stabiliser-torsion-box-2/documents"}}