{"id":"F2006B09635","name":"AD/F100/33 - Wheel-Speed Sensor Wiring","slug":"ad-f100-33-wheel-speed-sensor-wiring","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54437,"registerId":"commonwealth-F2006B09635-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F100/33 - Wheel-Speed Sensor Wiring","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/F100/33 Wheel-Speed Sensor Wiring 4/99\n\nApplicability: F.28 Mk.0100 aeroplanes listed in Fokker Service Bulletins (SB) F100-32-067 Revision 1 dated 6 July 1998 and F100-32-037 Revision 1 dated 4 December 1998.\n\nRequirement: 1. If not previously accomplished, modify the grounding of the wheel speed sensor wiring shielding in a0cordance with Part 1, 2, 3, or 4, as applicable, of the Accomplishment Instructions of Fokker SB F100-32-067 dated 12 March 1993 or Revision 1 dated 6 July 1998.\n\n2. Install new electrical grounding on the wheel speed sensor channel of the anti-skid control box in accordance with Part 1, 2, or 3, as applicable, of the Accomplishment Instructions of Fokker SB F100-32-037 Revision 2 dated 4 December 1998.\n\nNote: Netherlands AD 1998-100/2 refers.\n\nCompliance: 1. Prior to 1 August 1999.\n\n2. Prior to 15 February 2000.\n\nThis Airworthiness Directive becomes effective on 22 April 1999.\n\nBackground: The RLD received a report concerning an incident with a F.28 Mk.0100, where during approach, the liftdumpers inadvertently deployed. Preliminary investigation revealed that the outboard wheel speed signal was induced to ‘high’ by electromagnetic interference (EMI). The liftdumper arming test did not detect the signal because it was not transmitted until the skid control box was powered-up on landing gear DOWN selection.\n\nFurther analysis by the RLD of the liftdumper system protection against EMI, together with investigation into the Flight Control Computer failure mode which caused the EMI, have shown that aeroplanes with a post SB F100-32-067 configuration are significantly less susceptible to EMI on the wheel speed signals. This directive requires modification of the wheel speed sensor wiring shielding and the installation of new electrical grounding of the anti-skid system to prevent EMI.\n\nThe RLD has advised that these modification are considered a partial solution to the problem and that further rulemakeing is anticipated.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific electromagnetic interference issue with Fokker F100 aircraft. The scope remains precisely focused on the original safety problem identified — preventing inadvertent liftdumper deployment due to EMI on wheel-speed sensors. The background explicitly notes this is a 'partial solution' with further rulemaking anticipated, indicating the scope has not expanded beyond the original safety intent."},"complexity_factors":["Heavy reliance on external technical documents (Fokker Service Bulletins F100-32-067 and F100-32-037) — the actual work instructions are not contained in the directive itself","Multiple applicability conditions based on aircraft configuration and previous modifications ('if not previously accomplished')","Two separate compliance deadlines with different dates","Cross-reference to foreign aviation regulation (Netherlands AD 1998-100/2)","Technical terminology requiring aviation engineering knowledge (EMI, liftdumpers, wheel-speed sensor shielding, anti-skid control box)"],"plain_english_summary":"This Airworthiness Directive orders Fokker F100 operators to fix a dangerous EMI problem in wheel‑speed sensor wiring that can cause false signals and unintended liftdumper deployment during approach. It requires grounding/wiring modifications (per Fokker service instructions) by set deadlines and applies to any F100s not yet modified. The measure prevents potential loss of control on landing; Dutch authorities warn it’s a partial fix and further action may follow."},"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 Directive implements targeted wiring shielding and grounding modifications for the F.28 Mk.0100 fleet identified in the referenced service bulletins, consistent with the stated safety intent to reduce EMI‑induced false wheel‑speed signals. It does not expand applicability beyond the aircraft listed in the SBs; however, the regulator characterises the work as a partial solution and indicates further rulemaking may follow."},"complexity_factors":["Technical electrical work (shielding and grounding) requiring qualified maintenance personnel and shop resources","Multiple Fokker Service Bulletins and revisions referenced — operators must identify applicable SB revision per aircraft","Two distinct mandatory actions with different compliance dates (short and medium term)","Applicability limited to aircraft listed in the referenced SBs — requires cross‑checking fleet records","Operational risk remains partly unresolved (regulator calls it a partial solution), creating regulatory uncertainty and potential follow‑on mandates","Traceability and paperwork: compliance must be recorded against specific SB parts and AD requirements","Cross‑jurisdictional reference (Netherlands AD) may require coordination for internationally operated aircraft"],"plain_english_summary":"**What it does:** This Airworthiness Directive requires physical changes to Fokker F100 wheel‑speed sensor wiring—rework shielding ground connections per Fokker service bulletins and install a new ground on the anti‑skid control box channel.  \n**Who it affects and why it matters:** It applies to listed F.28 Mk.0100 aeroplanes, sets compliance deadlines, and aims to reduce electromagnetic‑interference‑induced false wheel‑speed signals that led to inadvertent liftdumper deployment; the regulator notes these changes are a partial solution and further rulemaking may follow."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f100-33-wheel-speed-sensor-wiring","history":"/api/acts/ad-f100-33-wheel-speed-sensor-wiring/history","analysis":"/api/acts/ad-f100-33-wheel-speed-sensor-wiring/analysis","conflicts":"/api/acts/ad-f100-33-wheel-speed-sensor-wiring/conflicts","importantCases":"/api/acts/ad-f100-33-wheel-speed-sensor-wiring/important-cases","documents":"/api/acts/ad-f100-33-wheel-speed-sensor-wiring/documents"}}