{"id":"F2006B03023","name":"AD/B747/122 - Ice and Rain Protection - Pitot Static and Temperature Probe Icing","slug":"ad-b747-122-ice-and-rain-protection-pitot-static-and-temperature-probe-icing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42382,"registerId":"commonwealth-F2006B03023-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/122 - Ice and Rain Protection - Pitot Static and Temperature Probe Icing","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)  \nBoeing 747 Series Aeroplanes\n\nAD/B747/122 Ice and Rain Protection \\- Pitot Static\n\nand Temperature Probe Icing\n\nApplicability: All model 747-400 series airplanes.\n\n  \n11/93\n\nDM\n\nRequirement: Action in accordance with Boeing Alert Service Bulletin 747-30A2069 dated 15 July 1993.\n\nNote: FAA AD 93-14-21 Amendment 39-8646 refers.\n\nCompliance: Prior to 1 December 1993.\n\nBackground: Operators have reported cases of aircraft entering the ground operating mode whilst still flying, due to depressurisation of the number four hydraulic system.\n\nThe Federal Aviation Administration (FAA) has determined that when there is a loss of pressure in hydraulic system number four, the wing gear trucks may relax sufficiently to exceed the tilted position indication, when this occurs on the sensing systems for both the left and right wing gear trucks, the aircraft will enter the “ground mode”. Additionally, if hydraulic system number one is depressurised and the body gear trucks relax sufficiently, the aircraft will enter the “ground mode” when the gear is extended for landing. FAA analysis indicates that various electrical and avionics systems, including the pitot and total air temperature heat systems, will be affected by this type of failure.\n\nCompliance with this Directive will reduce the effect on aircraft systems by ensuring that full pitot and total air temperature heat in the event of an aircraft entering “ground mode” of operation.\n\nA Flight Manual Amendment is required and will be issued under Approval Number A/QF747-4/27.","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, time-bound safety directive addressing a specific technical fault. It has not expanded beyond its original purpose of mandating a fix for pitot/static and temperature probe heating failures caused by erroneous ground mode activation."},"complexity_factors":["Single, specific aircraft type (747-400 series)","Single compliance action (follow Boeing Service Bulletin 747-30A2069)","Clear deadline (prior to 1 December 1993)","No nested exceptions or conditional logic","Only 4 defined elements: applicability, requirement, compliance date, and background","Straightforward causal chain explained in background (hydraulic failure → gear position error → ground mode → heating system failure)"],"plain_english_summary":"This Airworthiness Directive orders Boeing 747-400 operators in Australia to carry out a Boeing service bulletin modification to prevent pitot and temperature probe heaters from switching off if hydraulic failures make the aircraft falsely indicate it is on the ground. Required before 1 December 1993, the fix stops in‑flight sensor icing that can produce false airspeed/temperature indications and lead to loss of control."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument applies specifically to all 747-400 series aircraft and mandates action per the Boeing service bulletin with a fixed compliance date and a Flight Manual Amendment. The text does not expand the applicability beyond that stated or alter the stated technical mitigation; it cross-references FAA AD 93-14-21 but does not change scope from what the Directive explicitly prescribes (Applicability; Requirement; Note; Compliance)."},"complexity_factors":["Single mandatory action but technical detail is delegated to an external document: compliance is “in accordance with Boeing Alert Service Bulletin 747-30A2069 dated 15 July 1993” (Requirement).","Clear, short compliance deadline creates scheduling pressure for operators: “Prior to 1 December 1993” (Compliance).","Universal applicability narrows legal ambiguity but enlarges operational impact: “All model 747-400 series airplanes” (Applicability).","Operational safety linkage across systems increases implementation importance: FAA analysis ties hydraulic failures to multiple electrical/avionics systems including pitot and total air temperature heat (Background).","Regulatory paperwork and procedural change required: a Flight Manual Amendment is to be issued under a specified approval number, implying administrative compliance and potential training/ops updates (Flight Manual Amendment).","Cross-reference to an FAA AD (FAA AD 93-14-21) may require coordination or consistency with overseas compliance actions (Note)."],"plain_english_summary":"This airworthiness directive requires all Boeing 747‑400 operators to implement the actions in Boeing Alert Service Bulletin 747‑30A2069 (15 July 1993) so pitot/static and total air temperature probe heat remain effective if the aircraft unintentionally enters a “ground mode” while airborne. Compliance must be completed prior to 1 December 1993 and a Flight Manual Amendment will be issued under Approval Number A/QF747-4/27."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-122-ice-and-rain-protection-pitot-static-and-temperature-probe-icing","history":"/api/acts/ad-b747-122-ice-and-rain-protection-pitot-static-and-temperature-probe-icing/history","analysis":"/api/acts/ad-b747-122-ice-and-rain-protection-pitot-static-and-temperature-probe-icing/analysis","conflicts":"/api/acts/ad-b747-122-ice-and-rain-protection-pitot-static-and-temperature-probe-icing/conflicts","importantCases":"/api/acts/ad-b747-122-ice-and-rain-protection-pitot-static-and-temperature-probe-icing/important-cases","documents":"/api/acts/ad-b747-122-ice-and-rain-protection-pitot-static-and-temperature-probe-icing/documents"}}