{"id":"F2006B09916","name":"AD/F50/86 - Skid Control Unit","slug":"ad-f50-86-skid-control-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55123,"registerId":"commonwealth-F2006B09916-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor 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 CASR 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\n![](image.001.png)  \n\nFokker F50 (F27 Mk 50) Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/F50/86 Skid Control Unit 11/2003","sectionType":"part","heading":"AD/F50/86 Skid Control Unit 11/2003","content":"# AD/F50/86 Skid Control Unit 11/2003\n\nApplicability: Model F.27 Mk050, Mk.0502 and Mk.0604 aeroplanes, all serial numbers, equipped with Aircraft Braking Systems Corporation (ABSC) skid control units with Part Numbers (P/N) 6004125 or 6004125-1.\n\nRequirement: 1. Replace skid control units P/N 6004125 or 6004125-1 with P/N 6004125-2 units in accordance with Part 2 Accomplishment Instructions of Fokker Services Service Bulletin (SB) F50-32-038 dated 8 May 2003.\n\nNote 1: P/N 6004125 units are pre ABSC SB F50-32-4 and 6004125-1 units are post ABSC SB F50-32-4.\n\nNote 2: For modification of the skid control units refer to ABSC SB 6004125-32-01 dated 7 May 200.\n\n    2. Modify the skid control unit ground wiring in accordance with Part 2 Accomplishment Instructions of Fokker Services SB F50-32-035 dated 2 August 1999.\n\n    3. Skid control units P/N 6004125 or 6004125-1 may not be installed on any aeroplane as a replacement part.\n\nNote 3: CAA(NL) BLA 2003-091 (A) refers.\n\nCompliance: For Requirement 1:\n\nAeroplanes with skid control unit P/N 6004125 \\- Before 30 June 2004.\n\nAeroplanes with skid control unit P/N 6004125-1 \\- Before 30 December 2004.\n\nFor Requirement 2 \\- Before or concurrent with Requirement 1\\. For Requirement 3 - After 30 June 2004.\n\nThis Airworthiness Directive becomes effective on 30 October 2003.","sortOrder":1}],"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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD's scope is limited to specified Fokker F50 models equipped with the named ABSC skid control units and sets out replacement, wiring modification, and an installation ban with deadlines. The instrument does not expand or narrow that safety‑corrective scope within the text provided; it prescribes corrective actions and timing for the identified unsafe condition."},"complexity_factors":["Technical specificity: requirement ties to exact part numbers (6004125, 6004125-1, 6004125-2) and specific Fokker F50 models.","Multiple cross-references: relies on Fokker Service Bulletins (F50-32-038, F50-32-035) and an ABSC service bulletin for modification instructions.","Staggered compliance deadlines: different cut‑off dates for each part number and sequencing (wiring mod before or concurrent with replacement).","Installation prohibition: affirmative ban on reinstalling older units after the effective date, creating lifecycle controls on spares.","Operational impact: requires docking/time for replacement and wiring work, affecting scheduling and costs borne by operators.","Implementation risk: potential parts availability constraints and need for qualified maintenance providers to follow SB instructions.","Enforcement and discretion: CASA delegate issues the AD and sets compliance expectations; practical approval/acceptance of work relies on maintenance/inspector processes.","Document clarity issue: typographical/truncated year in an ABSC SB date in the text creates minor source ambiguity for implementers."],"plain_english_summary":"This Airworthiness Directive requires operators of certain Fokker F50 (F27 Mk050/0502/0604) aeroplanes fitted with ABSC skid control units P/N 6004125 or 6004125‑1 to replace those units with P/N 6004125‑2, modify skid-unit ground wiring, and prohibits reinstalling the older units. CASA issued it to correct an identified unsafe braking/skid-control condition. Operators pay for parts and maintenance, must meet staged deadlines, and choose timing and contractors subject to the AD and the referenced service bulletins; non‑compliance risks aircraft grounding."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive maintaining its original purpose: correcting a specific unsafe condition in a defined aircraft system. The scope remains tightly focused on skid control unit replacement and has not expanded beyond this safety-critical maintenance action."},"complexity_factors":["Single-purpose instrument with clear mechanical action required (replacement of specific part)","Only 2 defined part numbers in applicability, with straightforward replacement mapping","Simple conditional structure: if you have X part, do Y action by Z date","Minimal cross-referencing (only references 2 service bulletins and 1 foreign aviation notice)","No nested exceptions or complex definitional sections","Compliance dates are absolute calendar dates rather than flight hours or cycles"],"plain_english_summary":"This CASA safety order requires owners/operators of Fokker F50 (Mk.050, Mk.0502, Mk.0604) with Aircraft Braking Systems Corp. skid control units (P/N 6004125 and 6004125-1) to replace them with P/N 6004125-2 and modify the ground wiring per manufacturer instructions. Deadlines: oldest units by 30 Jun 2004, others by 30 Dec 2004; the old units are banned thereafter. Non‑compliance grounds aircraft from flying — it fixes a landing‑braking safety risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-86-skid-control-unit","history":"/api/acts/ad-f50-86-skid-control-unit/history","analysis":"/api/acts/ad-f50-86-skid-control-unit/analysis","conflicts":"/api/acts/ad-f50-86-skid-control-unit/conflicts","importantCases":"/api/acts/ad-f50-86-skid-control-unit/important-cases","documents":"/api/acts/ad-f50-86-skid-control-unit/documents"}}