{"id":"F2006B03178","name":"AD/B747/283 - Fuel Tank Limitations","slug":"ad-b747-283-fuel-tank-limitations","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42550,"registerId":"commonwealth-F2006B03178-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/B747/283 Fuel Tank Limitations 1/2003","sectionType":"part","heading":"AD/B747/283 Fuel Tank Limitations 1/2003 TX","content":"# AD/B747/283 Fuel Tank Limitations 1/2003 TX\n\nApplicability: All Model 747 series aeroplanes.\n\nRequirement: Revise the Limitations Section of the Aircraft Flight Manual (AFM) to include the following (this may be accomplished by inserting a copy of this Directive into the AFM):","sortOrder":1},{"sectionNumber":"Model 747-100, -200B, -200F, -200C, -100","sectionType":"part","heading":"Model 747-100, -200B, -200F, -200C, -100B, -300, -100B SUD, 747SR and 747SP","content":"## Model 747-100, \\-200B, \\-200F, \\-200C, \\-100B, \\-300, -100B SUD, 747SR and 747SP\n\nCERTIFICATE LIMITATIONS\n\nFueling and use of the centre auxiliary fuel tank and auxiliary fuel tanks 1 and 4 (if installed) is prohibited.\n\nThe centre wing tank (CWT) must contain a minimum of 17,000 pounds (7,700 kilograms) of fuel prior to engine start, if the CWT override/jettison pumps are to be selected ON during flight.\n\nThe CWT fuel quantity indication system must be operative to dispatch with CWT mission fuel.\n\nBoth CWT override/jettison pump switches must be selected OFF at or before the CWT fuel quantity reaches 7,000 pounds (3,200 kilograms), if the CWT fuel quantity is less than 50,000 pounds (22,700 kilograms) prior to engine start. The CWT override pumps may be selected ON during stabilized cruise conditio ns. Both CWT override/jettison pump switches must be selected OFF at or before the CWT fuel quantity reaches 3,000 pounds (1,400 kilograms).\n\nBoth CWT override/jettison pump switches must be selected OFF at or before the CWT fuel quantity reaches 3,000 pounds (1,400 kilograms), if the CWT fuel quantity is greater than or equal to 50,000 pounds (22,700 kilograms) prior to engine start.\n\nBoth CWT override/jettison pumps must be selected OFF when either CWT override/jettison fuel pump low pressure light illuminates.","sortOrder":2},{"sectionNumber":"Boeing 747 Series Aeroplanes","sectionType":"part","heading":"Boeing 747 Series Aeroplanes","content":"## Boeing 747 Series Aeroplanes\n\nAD/B747/283 (Continued)\n\nWarning\n\nDo not reset a tripped fuel pump circuit breaker.\n\nWarning\n\nDo not cycle the CWT pump switches from ON to OFF to ON with any continuous low pressure indication present.\n\nNote\n\nThe CWT may be emptied normally in an emergency fuel jettison.\n\nNote\n\nIn a low fuel situation, both CWT override/jettison pumps may be selected ON and all CWT fuel may be used.\n\nIf a centre wing tank pump fails with fuel in the centre tank, shut off the affected fuel pump.\n\nIf the main tanks are not full, the zero fuel gross weight of the aeroplane plus the weight of CWT tank fuel may exceed the maximum zero fuel gross weight by up to 7,000 pounds (3,200 kilograms) for takeoff, climb, cruise, descent, and landing, provided that the effects of balance (CG) have been considered.\n\nWhen defueling centre or main wing tanks, the Fuel Pump Low Pressure indication lights must be monitored and the fuel pumps positioned to OFF at the first indication of fuel pump low pressure. Defueling with passengers on board is prohibited.","sortOrder":3},{"sectionNumber":"Model 747-400, -400D, and -400F CERTIFIC","sectionType":"part","heading":"Model 747-400, -400D, and -400F CERTIFICATE LIMITATIONS","content":"## Model 747-400, \\-400D, and -400F CERTIFICATE LIMITATIONS\n\nFueling and use of the horizontal stabilizer tank (if installed) is prohibited.\n\nThe centre wing tank (CWT) must contain a minimum of 17,000 pounds (7,700 kilograms) prior to engine start, if the CWT override/jettison pumps are to be selected ON during flight.\n\nThe CWT fuel quantity indication system must be operative to dispatch with CWT mission fuel.","sortOrder":4},{"sectionNumber":"The limitations contained in this Direct","sectionType":"part","heading":"The limitations contained in this Directive supersede any conflicting basic Aircraft Flight Manual limitations.","content":"## The limitations contained in this Directive supersede any conflicting basic Aircraft Flight Manual limitations.\n\nAccomplishment of Requirement 2 of AD/B747/280 is acceptable for compliance with the requirements this Directive. This Directive does not require that those actions be repeated unless the terminating actions specified in Requirements 4, 6 and 7 of AD/B747/280 have been accomplished.\n\nAccomplishment of the terminating actions specified in Requirement 4, 6 and 7 of AD/B747/280, does not allow removal of the AFM revisions required by this Directive.\n\nNote: FAA Emergency AD 2002-24-51 and AD2002-24-52 refer.\n\nCompliance: Before 29 November 2002.\n\nThis Airworthiness Directive becomes effective on 26 November 2002.\n\nBackground: The United States Federal Aviation Administration has received reports indicating that two fuel tank pumps from different Model 747 series aeroplanes showed evidence of extreme localized overheating of parts in the priming and vapour pump section of the fuel pump. The priming and vapour pump section of the pump is open to the fuel tank via the pump inlet line and the vapour vent of the pump. The cause of this overheating is believed to be friction between the pump parts; however, the specific cause of the friction is unknown at this time.\n\nOverheating of the parts in the priming and vapour pump section of the fuel pump provides an ignition source in the fuel tank during dry running of the pump, which could result in fire/explosion of the fuel tank.","sortOrder":5}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD remains focused on the original safety problem identified in the background (pump overheating in the priming/vapour section creating a potential fuel‑tank ignition source). The measures are operational and procedural (AFM revisions, pump switching rules, tank‑use prohibitions) designed to mitigate that specific unsafe condition. It does not broaden the instrument beyond fuel‑tank/pump mitigation measures, although it links to other ADs for possible terminating design actions; this is consistent with the directive’s original safety purpose rather than a scope expansion."},"complexity_factors":["Applies to all Model 747 variants but contains separate rules for older 747 variants and the 747‑400 family (model‑specific provisions).","Multiple numeric fuel thresholds and conditional pump‑operation rules (17,000 lb, 50,000 lb, 7,000 lb, 3,000 lb) creating branching operational logic.","Several procedural warnings and notes that impose crew behaviour constraints (do not reset circuit breakers; do not cycle switches with continuous low‑pressure indication; defueling restrictions).","Cross‑reference to another AD (AD/B747/280) with conditional acceptance/terminating actions, creating dependency on external compliance actions.","Mandated AFM revision and the statement that these limitations override conflicting basic AFM limitations (administrative and legal precedence).","Interaction between dispatch conditions (operative CWT indication required) and in‑flight pump usage rules (operational and maintenance dependency).","Short compliance timeline and explicit compliance date (administration/implementation pressure)."],"plain_english_summary":"**What this directive does (mechanically)**\n\n- Requires operators of all Boeing 747 series aeroplanes to revise the Aircraft Flight Manual (AFM) Limitations section (you may insert a copy of this AD into the AFM) so crews must follow new fuel‑tank operating and fueling rules. (Requirement section.)\n\n- For older 747 models (747‑100/200 series, 747‑300, 747SP, 747SR and variants) the AFM must state: \n  - Do not fuel or use the centre auxiliary fuel tank and auxiliary tanks 1 and 4, if those tanks are installed. (Certificate limitations.)\n  - If the crew intends to select the centre wing tank (CWT) override/jettison pumps ON in flight, the CWT must contain at least 17,000 lb (7,700 kg) of fuel before engine start. (Certificate limitations.)\n  - The CWT fuel quantity indication system must be operative when dispatching with CWT fuel for the mission. (Certificate limitations.)\n  - Detailed rules when the CWT override/jettison pump switches must be turned OFF depending on the CWT fuel quantity before engine start (different trigger points at 50,000 lb, 7,000 lb and 3,000 lb). (Certificate limitations.)\n  - Both CWT override/jettison pumps must be turned OFF if either low‑pressure light for those pumps illuminates. (Certificate limitations.)\n  - Warnings: do not reset a tripped fuel pump circuit breaker; do not cycle the CWT pump switches ON‑OFF‑ON if a continuous low‑pressure indication is present. (Warnings/Notes.)\n  - Operational notes about jettisoning CWT fuel in an emergency, using all CWT fuel in low fuel situations, shutting off a failed CWT pump, the possibility to exceed maximum zero fuel weight by up to 7,000 lb in specified circumstances (provided centre of gravity effects are considered), and rules for defueling (monitor low pressure lights; turn pumps OFF at first low pressure indication; no defueling with passengers onboard). (Notes/Certificate limitations.)\n\n- For 747‑400 family models (‑400, ‑400D, ‑400F) the AFM must additionally prohibit fueling and use of the horizontal stabilizer tank if installed, and must include the same minimum CWT fuel, indication, and pump‑operation requirements noted above. (Certificate limitations.)\n\n- The AD’s AFM limitations override any conflicting basic AFM limitations. (Directive note.)\n\n- Compliance deadline: the AFM revision must be done by the stated compliance date in the AD. (Compliance section.)\n\n**Why the rule exists (stated reason)**\n\n- The FAA reported two incidents where fuel tank pumps on 747s showed extreme localized overheating in the priming/vapour pump section. That section is open to the tank via the pump inlet and vapour vent. The overheating is believed to be caused by friction between internal pump parts, producing an ignition source during dry running (pump running without adequate fuel), which could cause fire/explosion in the fuel tank. The AFM restrictions are intended to reduce the risk of dry‑running, limit operation of pumps in risky fuel quantities, ensure crews have fuel‑quantity indications available, and set safe procedures for defueling, jettisoning and pump failure response. (Background and Requirement sections.)\n\n**Who this affects**\n\n- Airlines and operators that fly any Boeing 747 model covered by the AD. They must update AFMs, train flight crews and ground staff, and follow the new fueling, defueling and in‑flight pump‑operation procedures.\n\n- Maintenance organisations and pilots: required to follow the no‑reset/no‑cycle warnings and to respond to pump low‑pressure indications by shutting pumps off (operational and maintenance behaviour change). \n\n**Concrete implications, trade‑offs and costs**\n\n- Operational flexibility: The restrictions limit how crews may manage fuel between tanks in flight (e.g. selecting CWT override pumps ON is constrained by pre‑start fuel quantities and low‑pressure indications). That reduces fuel‑management options for balancing and long‑range fuel use, potentially requiring additional uplift, weight/payload trade‑offs, or changes to flight planning. (Certificate limitations.)\n\n- Payload and refuelling costs: Prohibiting use of some auxiliary tanks (and the horizontal stabilizer tank on some models) removes usable fuel capacity in affected aeroplanes. Operators may need more refuelling stops or reduce payload to meet range requirements, increasing costs. (Certificate limitations.)\n\n- Turnaround and ground operations: The prohibition on defueling with passengers aboard may require additional ground time or offload procedures in some circumstances. Monitoring for fuel pump low‑pressure indications during defueling creates a procedural burden. (Notes/Certificate limitations.)\n\n- Training and administrative cost: Operators must revise AFMs, issue temporary revisions or placards, update operating procedures, and train flight crews and ground staff. There is also the cost of compliance tracking and possible increased maintenance calls when pumps trip or low‑pressure indications occur. (Requirement; Warnings/Notes.)\n\n- Safety benefit vs. cost: The benefits are safety‑oriented and diffuse (reduction of rare but high‑consequence tank ignition events). The immediate costs are borne by operators (fuel planning, payload, operations, training), concentrated on those who still operate 747 types. \n\n- Longer‑term technical fixes: The AD references terminating actions in another AD (AD/B747/280). If operators accomplish the terminating actions specified there, some requirements of this AD may be addressed, but this AD’s AFM revisions must remain unless the separate terminating actions allow removal. That creates an interaction between short‑term operational mitigations and longer‑term design/repair solutions. (Directive note referencing AD/B747/280.)\n\n**Implementation risks and human factors**\n\n- This AD relies on correct crew and ground behaviour: monitoring fuel quantities and low‑pressure lights, switching pumps OFF at specified thresholds, and obeying the ‘‘do not reset’’ and ‘‘do not cycle’’ warnings. This introduces scope for human error, especially in atypical flight or ground situations, leading to operational disruption or non‑compliance. (Warnings/Notes/Certificate limitations.)\n\n- The rules require an operative CWT quantity indication system for dispatch when CWT fuel is used, so dispatch decisions depend on functioning sensors. If sensors fail, dispatch with CWT fuel is prohibited, which affects sortie capability. (Certificate limitations.)\n\n**Market and competition effects (brief)**\n\n- Operators of older 747 variants may face higher marginal operating costs and reduced competitiveness relative to carriers operating newer aircraft or 747s that have accomplished design‑change terminating actions. Independent maintenance organisations may see increased business for AFM updates or repairs, but no special regulatory discretion or subsidy is created by the AD. \n\n**Other notes**\n\n- The AD explicitly supersedes any conflicting AFM limitations and cross‑references related FAA Emergency ADs. (Directive notes and Background.)\n\nOverall, this AD imposes specific AFM limitations and operational constraints on fuel tank use and pump operation to mitigate a reported risk of pump overheating and potential ignition. It shifts operational behaviour, planning and some costs onto aircraft operators while preserving the option for longer‑term design fixes under related ADs."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow scope as an emergency safety intervention targeting a specific mechanical defect in Boeing 747 fuel pumps. The requirements remain tightly focused on flight manual amendments and operational procedures to mitigate the identified ignition risk."},"complexity_factors":["Multiple aircraft variants with slightly different requirements (older 747 models vs 747-400 series)","Precise numerical thresholds (fuel weights in both pounds and kilograms, multiple quantity cut-offs at 50,000, 17,000, 7,000 and 3,000 pounds)","Conditional logic ('if...then' rules) for pump operation based on fuel quantities and flight phases","Cross-reference to related directives (AD/B747/280) with complex interaction rules about what satisfies compliance","Technical aviation terminology requiring specialist knowledge (CWT override/jettison pumps, AFM, dispatch, CG considerations)"],"plain_english_summary":"Australia’s aviation regulator issued an urgent safety order for Boeing 747s requiring changes to fuel management to prevent tank explosions: banning use of certain auxiliary and stabilizer tanks and imposing minimum centre-wing fuel levels, pump-off rules, working gauges, and new emergency procedures after fuel-pump overheating risks were found.\n\nIt applies to all 747 operators in Australia (passenger and cargo, multiple 747 variants) with compliance by 29 November 2002."},"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-b747-283-fuel-tank-limitations","history":"/api/acts/ad-b747-283-fuel-tank-limitations/history","analysis":"/api/acts/ad-b747-283-fuel-tank-limitations/analysis","conflicts":"/api/acts/ad-b747-283-fuel-tank-limitations/conflicts","importantCases":"/api/acts/ad-b747-283-fuel-tank-limitations/important-cases","documents":"/api/acts/ad-b747-283-fuel-tank-limitations/documents"}}