{"id":"F2005L02060","name":"AD/F100/69 - Landing Gear Integrated Axle Nut and Spacer","slug":"ad-f100-69-landing-gear-integrated-axle-nut-and-spacer","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":36238,"registerId":"commonwealth-F2005L02060-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Fokker F100 (F28 Mk 100) Series Aeroplan","sectionType":"division","heading":"Fokker F100 (F28 Mk 100) Series Aeroplanes","content":"### Fokker F100 (F28 Mk 100) Series Aeroplanes\n\n| AD/F100/69 | Landing Gear Integrated Axle Nut and Spacer | 9/2005 |\n| ---------- | ------------------------------------------- | ------ |\n\n| Applicability: | Fokker Aircraft B.V. F28 Mark 0070 and Mark 0100 aircraft, all serial numbers equipped with Messier-Dowty (formerly known as Dowty Rotol and Dowty Aerospace Gloucester) Main Landing Gear (MLG) units. |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Replace each MLG wheel axle-nut and spacer with an integrated axle-nut/spacer assembly in accordance with the accomplishment instructions of Messier-Dowty SB F100-32-72 dated 25 January 1995 or later CAA (United Kingdom) approved revisions.2. Amend the Aircraft Maintenance Manual (AMM) and Illustrated Parts Catalogue (IPC) in accordance with the instructions of Fokker Manual ChangeNotification - Maintenance (MCNM) F100-033 dated 30 April 1999.Note 1: Fokker 70/100 Service Letter (SL) 102 Revision 1 dated 12 February 1998; and Fokker Services SB F100-32-096 Revision 2 dated 29 April 2005 also pertain to this subject.Note 2: Civil Aviation Authority Netherlands Airworthiness Directive NrNL-2005-008 refers. |\n| Compliance: | 1. Within the next 12 calendar months after the effective date of this directive.2. Prior to or at the same time as the replacement as required by Requirement 1 of this directive. |\n| | This Airworthiness Directive becomes effective on 1 September 2005. |\n| | Over the years, several Fokker 100 (F28 Mark 0100) operators reported that a MLG wheel fell off during regular operation of the aircraft. These incidents occurred due to a missing spacer, which had inadvertently not been installed during a previous wheel change. Omitting the installation of the wheel spacer allows the wheel to move sideways along the axle, which subsequently leads to bearing failure, followed by loss of the wheel. Investigation by Fokker and Messier-Dowty has shown that two separate items, the spacer and the axle nut, can be replaced by a single axle-nut/spacer assembly, to prevent the possibility of omitting the spacer. In 1995, Messier-Dowty issued Service Bulletin (SB) F100-32-72 to make sure that the operator does not assemble the axle nut without the spacer. Fokker subsequently issued SB F100-32-096 to notify Fokker 100 operators of the (optional) Messier-Dowty SB’s existence. |\n\n| Background: | At a later stage, Fokker revised the SB to the status of ‘recommended”. In spite of all this attention to the spacer problem, wheel losses are still being reported due to missing wheel nut spacers. This condition, if not corrected, may lead to further wheel loss incidents, each of which could conceivably result in loss of control of the aircraft during the take-off run, landing rollout or taxiing operations. Since a potentially unsafe condition has been identified that may exist or develop on aircraft of the same type design, this Airworthiness Directive requires the replacement of the axle-nut and spacer with an integrated axle-nut/spacer assembly. In addition, the AMM and IPC must be amended to prevent reversal to a separate axle- nut and spacer installation during a subsequent wheel change. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n\n![](image.001.png) \nDavid Villiers \nDelegate of the Civil Aviation Safety Authority\n\n21 July 2005","sortOrder":0},{"sectionNumber":"AD/F100/69","sectionType":"part","heading":"AD/F100/69","content":"## AD/F100/69","sortOrder":1},{"sectionNumber":"Landing Gear Integrated Axle Nut and Spa","sectionType":"part","heading":"Landing Gear Integrated Axle Nut and Spacer","content":"## Landing Gear Integrated Axle Nut and Spacer","sortOrder":2},{"sectionNumber":"9/2005","sectionType":"part","heading":"9/2005","content":"## 9/2005","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope. It addresses a specific, well-defined safety defect (missing wheel spacers on Fokker F100 main landing gear) with a targeted technical solution. The directive does not expand beyond its original purpose of mandating a hardware modification to prevent wheel detachment."},"complexity_factors":["Single, specific technical requirement with clear manufacturer reference (Messier-Dowty SB F100-32-72)","Straightforward two-part compliance structure (physical replacement + documentation update)","Simple 12-month compliance window with no conditional exceptions or phased implementation","Limited applicability scope (specific aircraft type, specific landing gear manufacturer)","No nested definitions or extensive cross-referencing to other legislation — references are to technical manufacturer documents only","Background narrative explains rationale clearly without legal obfuscation"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Fokker 70/100 aircraft with Messier‑Dowty main landing gear to replace the two‑piece wheel axle‑nut and spacer with a single integrated axle‑nut/spacer assembly. The change—mandatory within 12 months—prevents the spacer‑omission maintenance error that led to wheels coming off during taxi, takeoff or landing. Operators must also amend maintenance manuals to mandate the new part."},"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The directive converts an earlier 'recommended' service bulletin into a mandatory requirement and adds compulsory AMM/IPC amendments. Previously the SB was advisory (Background); the AD makes installation of the integrated axle-nut/spacer and procedural changes compulsory and enforceable within a set timeframe (Requirement; Compliance)."},"complexity_factors":["Fleet-wide applicability to all serial numbers with specified MLG units — affects entire operator fleets (Applicability).","Mandatory hardware change: replace axle-nut and spacer with integrated assembly (Requirement 1).","Mandatory regulatory documentation updates: amend AMM and IPC to prevent reversion to separate parts (Requirement 2).","Dependence on manufacturer service bulletin and national authority approvals: compliance per Messier‑Dowty SB F100-32-72 or later CAA(UK)-approved revisions (Requirement 1).","Multiple cross-references to prior service letters and directives, increasing administrative tracing (Notes/Background).","Fixed compliance window (within 12 calendar months and timing relative to replacement) requiring scheduling of maintenance resources (Compliance).","Safety rationale grounded in repeated incidents of missing spacers leading to bearing failure and wheel loss (Background)."],"plain_english_summary":"This directive requires operators of Fokker F28 Mark 0070/0100 aeroplanes fitted with Messier‑Dowty main landing gear to replace separate wheel axle-nuts and spacers with a single integrated axle‑nut/spacer assembly and to update the Aircraft Maintenance Manual and Illustrated Parts Catalogue. It makes a previously recommended service bulletin mandatory to reduce incidents of wheel loss caused by missing spacers. Operators must carry out the work within 12 calendar months and schedule parts and labour accordingly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f100-69-landing-gear-integrated-axle-nut-and-spacer","history":"/api/acts/ad-f100-69-landing-gear-integrated-axle-nut-and-spacer/history","analysis":"/api/acts/ad-f100-69-landing-gear-integrated-axle-nut-and-spacer/analysis","conflicts":"/api/acts/ad-f100-69-landing-gear-integrated-axle-nut-and-spacer/conflicts","importantCases":"/api/acts/ad-f100-69-landing-gear-integrated-axle-nut-and-spacer/important-cases","documents":"/api/acts/ad-f100-69-landing-gear-integrated-axle-nut-and-spacer/documents"}}