{"id":"F2006B09620","name":"AD/F100/2 - Main Landing Gear Downlock - Inspection/Replacement","slug":"ad-f100-2-main-landing-gear-downlock-inspection-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54385,"registerId":"commonwealth-F2006B09620-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F100/2 - Main Landing Gear Downlock - Inspection/Replacement","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/F100/2 Main Landing Gear Downlock \\- Inspection/Replacement\n\n  \n1/99\n\nApplicability: F28 Mk. 100 aircraft all serial numbers, fitted with Dowty Aerospace Hydraulics MLG Downlock Actuators (Jack & Springpot Units) Part Number (P/N) 201218001, P/N 201218002, P/N 201218003, or P/N 201218004, all serial numbers.\n\nRequirement: 1. Inspect the applicable MLG Downlock Actuator in accordance with Fokker Service Bulletin SB F100-32-072 dated 30 March 1993 and in accordance with Dowty Aerospace Hydraulics SB F100-32-505 dated 24 March 1993.\n\n2. Replace MLG Downlock Actuator in accordance with the Aircraft Maintenance Manual Chapter 32-32-05 and return the defective unit to the manufacturer for further analysis.\n\nNote: RLD Airworthiness Directive 93-052 (A) dated 23 April 1993 refers.\n\nCompliance: 1. At intervals not to exceed 1250 flight hours.\n\n2. Following failure to meet the requirements of the inspection at requirement 1 above.\n\nThis Airworthiness Directive becomes effective on 28 January 1999.\n\nBackground: In service experience had revealed arisings of landing gear “unsafe” warnings which had been attributed to MLG Downlock actuator internal failures. This Directive is issued to introduce regular inspections to ensure correct operation of the MLG Downlock actuators.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical failure mode in a specific aircraft type. It has not expanded beyond its original purpose of ensuring MLG Downlock actuator airworthiness."},"complexity_factors":["Single, specific mechanical component targeted (MLG Downlock Actuator)","Only 4 specific part numbers affected","Straightforward two-step compliance: inspect periodically, replace if failed","Clear numerical compliance threshold (1250 flight hours)","References to external technical documents (Service Bulletins) rather than embedding technical specifications","No nested exceptions, conditional logic, or defined terms section","Single aircraft type and variant (F28 Mk. 100)","Total length: approximately 250 words"],"plain_english_summary":"This Airworthiness Directive for Fokker F100 aircraft mandates regular inspection and, if necessary, replacement of specific Dowty main landing gear downlock actuators (P/Ns 201218001–201218004). It responds to internal actuator failures that caused false “unsafe” gear warnings and risked the gear not locking. Operators must inspect units every 1,250 flight hours per the Fokker/Dowty service bulletins and return any failed actuators to the manufacturer. Effective 28 January 1999."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD retains the original, narrow scope: it targets the same F28 Mk.100 fleet fitted with the listed Dowty actuator part numbers and imposes recurring inspections and replacement-on-failure as described in the Background and Requirements. It does not expand applicability or introduce additional categories of work beyond inspection, replacement and return for analysis."},"complexity_factors":["Narrow technical scope — applies only to F28 Mk.100 aircraft fitted with four specific Dowty actuator P/Ns (Applicability).","Recurring compliance interval — inspections required at intervals not to exceed 1250 flight hours (Compliance).","Dependency on external service documents — inspections must follow two separate service bulletins (Requirement 1).","Mandatory replacement and returns — failed units must be replaced per the Aircraft Maintenance Manual and returned to manufacturer for analysis (Requirement 2).","Operational impact — potential for unscheduled removals and associated downtime if inspections reveal defects (Background; Compliance 2).","Traceability and administrative burden — need to track hours, inspection results, replacements and returns to manufacturer (Requirement; Compliance)."],"plain_english_summary":"This Airworthiness Directive requires operators of Fokker F28 Mk 100 aircraft fitted with specified Dowty main landing gear (MLG) downlock actuators to perform recurring inspections using the cited Fokker and Dowty service bulletins and to replace any actuator that fails inspection under the Aircraft Maintenance Manual, returning defective units to the manufacturer. Operators pay for inspections, replacements and returns; maintenance personnel must carry out the work on the timetable set by the AD (Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f100-2-main-landing-gear-downlock-inspection-replacement","history":"/api/acts/ad-f100-2-main-landing-gear-downlock-inspection-replacement/history","analysis":"/api/acts/ad-f100-2-main-landing-gear-downlock-inspection-replacement/analysis","conflicts":"/api/acts/ad-f100-2-main-landing-gear-downlock-inspection-replacement/conflicts","importantCases":"/api/acts/ad-f100-2-main-landing-gear-downlock-inspection-replacement/important-cases","documents":"/api/acts/ad-f100-2-main-landing-gear-downlock-inspection-replacement/documents"}}