{"id":"F2006B03412","name":"AD/B767/58 - Left Hydraulic System","slug":"ad-b767-58-left-hydraulic-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42953,"registerId":"commonwealth-F2006B03412-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B767/58 - Left Hydraulic System","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 767 Series Aeroplanes\n\nAD/B767/58 Left Hydraulic System 9/91\n\nApplicability: Boeing 767 series Aeroplanes as listed in Boeing Alert Service Bulletin 767- 29A0038, dated 3 August 1989.\n\nRequirement: Action in accordance with the Technical Requirements of FAA AD 91-12-16.\n\nNote: FAA AD 91-12-16 refers to Boeing Alert Service Bulletin 767-29A0038, Amendment 39-7028.\n\nCompliance: Required within 3600 hours time-in-service or 24 months from the issue date of this AD, whichever occurs later.\n\nBackground: FAA AD action was prompted by review and analysis of the B767 flight control system functional redundancy as it relates to the ability of the aeroplane to continue safe flight and landing after structural failure. This condition, if not corrected, could result in loss of controllability of the aeroplane if, following a single event of structural failure, damage occurs to all three hydraulic systems.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD adopts and enforces the technical requirements of FAA AD 91-12-16 and identifies applicability by reference to Boeing Alert Service Bulletin 767-29A0038. The instrument does not expand or narrow the listed applicability or the mandated technical content in the text provided; it instead makes the FAA AD and Boeing service bulletin mandatory for the listed Boeing 767 aeroplanes (Applicability; Requirement; Note)."},"complexity_factors":["The AD does not reproduce the technical requirements; it mandates compliance with FAA AD 91-12-16 and a Boeing Alert Service Bulletin, so implementers must obtain and interpret external technical documents (Requirement; Note).","Applicability is limited to aircraft listed in the Boeing service bulletin, requiring operators to cross-check serial numbers against an external list (Applicability; Note).","The subject matter is safety-critical (hydraulic and flight control redundancy), which requires specialised maintenance skills and certified organisations to implement the work (Background; Requirement).","Compliance timing is a dual trigger (3,600 flight hours or 24 months, whichever is later), requiring operators to track both calendar and utilisation metrics for scheduling (Compliance).","Responsibility, costs and execution rest with operators and contracted maintenance organisations, introducing operational and budgetary coordination (Requirement; Compliance)."],"plain_english_summary":"What this instrument does, in plain language\n\n- This Airworthiness Directive (AD) requires operators of certain Boeing 767 aeroplanes to carry out the technical actions set out in FAA AD 91-12-16 (which itself refers to Boeing Alert Service Bulletin 767-29A0038 dated 3 August 1989). The directive applies only to the Boeing 767 series aeroplanes listed in that Boeing service bulletin (Applicability; Requirement; Note).\n\n- The AD must be complied with within 3,600 flight hours time-in-service or 24 months from the AD’s issue date, whichever is later (Compliance).\n\nWho decides and who acts\n\n- The Civil Aviation Safety Authority (CASA) requires compliance by issuing this AD, but it achieves the requirement by mandating the technical content of the FAA AD and the Boeing service bulletin (Requirement; Note). Aircraft operators (airlines or owners) are the parties who must arrange and pay for the work. The work will typically be done by the operator’s maintenance organisation or contracted maintenance providers.\n\nWhat behaviour changes and what gets done mechanically\n\n- Operators must perform inspections, modifications or repairs specified in FAA AD 91-12-16 and Boeing Alert Service Bulletin 767-29A0038. The AD does not itself list the technical steps; it makes compliance with those external documents mandatory (Requirement; Note).\n\nWhy the AD was issued (as stated in the source) and the safety mechanism\n\n- The AD cites FAA analysis of the Boeing 767 flight control system redundancy. The FAA concluded that, following certain structural failures, there is a risk that damage could occur to all three hydraulic systems, and that condition could lead to loss of controllability if not corrected (Background). The AD therefore requires the actions in FAA AD 91-12-16 to address that risk (Requirement; Background).\n\nCosts, incentives and trade-offs (mechanical and operational effects)\n\n- Who pays: aircraft operators bear direct costs of compliance (inspections, parts, labour, aircraft downtime). Costs are concentrated on the operators of the affected fleet because the AD applies to specific Boeing 767 aircraft (Applicability; Compliance).\n\n- Incentives and behaviour: operators have a regulatory incentive to implement the mandated technical work within the stated timeframe to keep aircraft airworthy and avoid regulatory penalties. Maintenance providers gain work from performing the mandated actions; operators may choose to use their in-house maintenance or contract out, subject to usual airworthiness approval and contractual freedom.\n\n- Trade-offs and opportunity costs: time in the maintenance hangar and resources spent on the mandated actions are not available for other maintenance or operational activities. The AD makes a particular set of technical tasks compulsory rather than optional, so operators must reallocate maintenance scheduling and budgets accordingly (Requirement; Compliance).\n\n- Compliance burden and implementation risk: the AD creates an administrative and operational burden to locate the affected serial numbers (via the Boeing service bulletin), interpret and implement the FAA AD’s technical requirements, and complete the work within the deadline. The AD delegates the technical detail to the FAA AD and Boeing service bulletin, so implementers must consult those documents to perform the correct work (Requirement; Note). If the technical actions are not completed, the background states the risk is reduced controllability after certain structural failures (Background).\n\nDiscretion and enforcement\n\n- The AD leaves little substantive discretion about what must be done because it directly requires compliance with the technical requirements of FAA AD 91-12-16 and the Boeing service bulletin. CASA enforces compliance through the usual airworthiness oversight mechanisms (Requirement; Note).\n\nEffects on markets, competition and private choice (practical points)\n\n- The AD affects only operators of the specified Boeing 767 aircraft; it does not change ownership or broader market rules. It creates demand for maintenance labour, parts and possibly engineering approvals; those effects are concentrated on affected operators and maintenance providers. It does not itself set prices or change the competitive rules for air transport, but it may impose additional operating cost on affected carriers (Applicability; Requirement; Compliance).\n\nSource citations: Applicability; Requirement; Note; Compliance; Background."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standalone airworthiness directive with a narrow, specific safety purpose. It has not expanded beyond its original intent of addressing hydraulic system vulnerability in Boeing 767 aircraft following structural failure scenarios."},"complexity_factors":["Short, single-purpose directive (approximately 200 words)","Only 4 structural sections: Applicability, Requirement, Note, Compliance, and Background","Heavy reliance on external documents — the actual technical requirements are contained in referenced FAA AD 91-12-16 and Boeing Service Bulletin 767-29A0038, not in the text itself","No defined terms section — uses standard aviation terminology without local definitions","Simple conditional logic: single deadline calculation ('whichever occurs later')","No nested exceptions or complex cross-referencing within the document itself"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific Boeing 767 aircraft.\n\n**What it does:**\n- Requires owners and operators of certain Boeing 767 series planes to carry out specific maintenance or modifications to the **left hydraulic system**\n- The exact technical work required is set out in an American Federal Aviation Administration (FAA) directive (AD 91-12-16), which in turn references a Boeing service bulletin\n\n**Who it affects:**\n- Operators of Boeing 767 aircraft covered by Boeing Alert Service Bulletin 767-29A0038 (dated August 1989)\n- This typically means airlines and cargo operators flying these specific aircraft models in Australia\n\n**Why it matters:**\n- The safety issue involves **flight control redundancy** — basically, having backup systems so the plane can still be controlled if something fails\n- Without this fix, a single structural failure could potentially damage all three hydraulic systems, leading to **complete loss of aircraft control**\n- Hydraulic systems power critical flight controls (like flaps, rudders, and landing gear), so losing all three would be catastrophic\n\n**When it must be done:**\n- Within 3,600 flight hours **or** 24 months from when the directive was issued — whichever comes later\n\n**Key point:** This is a **compliance document** — it doesn't contain the technical instructions itself, but legally mandates that operators follow the referenced Boeing/FAA technical documents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b767-58-left-hydraulic-system","history":"/api/acts/ad-b767-58-left-hydraulic-system/history","analysis":"/api/acts/ad-b767-58-left-hydraulic-system/analysis","conflicts":"/api/acts/ad-b767-58-left-hydraulic-system/conflicts","importantCases":"/api/acts/ad-b767-58-left-hydraulic-system/important-cases","documents":"/api/acts/ad-b767-58-left-hydraulic-system/documents"}}