{"id":"F2006B03151","name":"AD/B747/252 - Pitot Static Probe Wiring","slug":"ad-b747-252-pitot-static-probe-wiring","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42523,"registerId":"commonwealth-F2006B03151-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\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 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\n![](image.001.png)\n\nBoeing 747 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B747/252 Pitot Static Probe Wiring 8/","sectionType":"part","heading":"AD/B747/252 Pitot Static Probe Wiring 8/2001","content":"# AD/B747/252 Pitot Static Probe Wiring 8/2001\n\nApplicability: Model 747-400 series airplanes, as listed in Boeing Alert Service Bulletin (ASB) 747- 30A2078, Revision 1, dated 16 November 2000.\n\nRequirement: 1. Perform a special detailed inspection to detect miswiring of diodes in the heating system of the pitot static probes in accordance with ASB 747-30A2078, Revision 1.\n\nInspections accomplished prior to the effective date of this Directive in accordance with ASB 747-30A2078, dated 24 August 2000, are acceptable for compliance with the action specified in Requirement 1.\n\n2. If any miswiring is found during the Requirement 1 inspection, rewire per Boeing 747-400 Wiring Diagrams 30-31-11 and 30-31-21, as referenced in ASB 747- 30A2078, Revision 1.\n\nNote 1: For the purposes of this Directive, a special detailed inspection is defined as: “An intensive examination of a specific item(s), installation, or assembly to detect damage, failure, or irregularity. The examination is likely to make extensive use of specialized inspection techniques and/or equipment. Intricate cleaning and substantial access or disassembly procedures may be required.”\n\nNote 2: FAA AD 2001-12-14 Amdt 39-12269 refers.\n\nCompliance: For Requirement 1 \\- Within 15 months after the effective date of this Directive.\n\nFor Requirement 2 - Before further flight after the Requirement 1 inspection. This Airworthiness Directive becomes effective on 9 August 2001.\n\nBackground: Boeing advised that several operators reported burnt diodes in the Pitot Probe Heat System. The cause of the anomalies was determined to be miswiring of the diodes in the power reduction circuitry. Reduced power to the heating system of the pitot static probes could lead to ice accumulation on the pitot static probes. Ice accumulation may result in erroneous airspeed or altitude indications to the flight crew, and consequent reduced safety of flight.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD confines action to Boeing 747-400 series aircraft as listed in the referenced Boeing ASB and cross-references FAA AD 2001-12-14; the text contains no indication of expansion or narrowing of that applicability beyond the cited service bulletin (Applicability; Note 2)."},"complexity_factors":["Technical specificity: requires a 'special detailed inspection' defined to potentially need specialized techniques, cleaning, and disassembly (Note 1).","Narrow applicability: applies only to Model 747-400 series airplanes listed in Boeing ASB 747-30A2078, Revision 1 (Applicability).","External normative documents: compliance depends on Boeing Alert Service Bulletin 747-30A2078 Rev 1 and Boeing wiring diagrams 30-31-11 and 30-31-21 (Requirement, Requirement 2).","Timing constraints: inspection must be done within 15 months and any rewiring must be completed before further flight, creating potential operational disruption (Compliance; Requirement 2).","Regulatory authority: issued by CASA under subregulation 39.1(1) of CAR 1998, centralising the decision to the CASA delegate (header).","Safety rationale tied to specific failure mode: miswiring caused burnt diodes and reduced power to pitot heating, with risk of icing and erroneous airspeed/altitude (Background).","Prior-action acceptance: inspections performed under the earlier ASB dated 24 Aug 2000 are accepted, limiting retrospective compliance cost for some operators (Requirement).","Immediate grounding risk: requirement to rewire 'before further flight' if miswiring is found creates a hard operational and cost consequence for affected aircraft (Requirement 2; Compliance)."],"plain_english_summary":"*Boeing 747‑400* operators must carry out a special detailed inspection for miswired diodes in the pitot‑probe heating system and rewire any probes found faulty before further flight. CASA issued the directive because miswiring can reduce probe heating, allow ice build‑up, and lead to erroneous airspeed or altitude readings. Operators bear the cost and scheduling impact; the AD sets specific deadlines (inspection within 15 months; repairs before next flight) and points to Boeing service instructions."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with a narrow, specific safety purpose. It addresses a defined technical issue (miswiring of diodes in pitot probe heating systems) for a specific aircraft model. There is no indication of scope creep; the directive remains tightly focused on its original safety intent."},"complexity_factors":["Short, single-purpose directive with only 2 requirements","Minimal defined terms (only 1 explicit definition in Note 1)","Single cross-reference to FAA AD 2001-12-14","Clear applicability limited to specific aircraft model and service bulletin","Straightforward compliance timeline (15 months for inspection, immediate for repairs)","No nested exceptions or conditional logic beyond the basic 'if found, then fix' structure"],"plain_english_summary":"CASA has issued a safety order for Boeing 747‑400s requiring operators to inspect pitot‑static probe heating diode wiring within 15 months and correct any miswiring before further flight. It applies to aircraft listed in the relevant Boeing service bulletin. The action prevents probe icing that can produce false airspeed/altitude readings and reduce flight safety."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-252-pitot-static-probe-wiring","history":"/api/acts/ad-b747-252-pitot-static-probe-wiring/history","analysis":"/api/acts/ad-b747-252-pitot-static-probe-wiring/analysis","conflicts":"/api/acts/ad-b747-252-pitot-static-probe-wiring/conflicts","importantCases":"/api/acts/ad-b747-252-pitot-static-probe-wiring/important-cases","documents":"/api/acts/ad-b747-252-pitot-static-probe-wiring/documents"}}