{"id":"F2007L01059","name":"AD/BAe 146/127 - Hydraulic Power - Accumulator Cylinders","slug":"ad-bae-146-127-hydraulic-power-accumulator-cylinders","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65016,"registerId":"commonwealth-F2007L01059-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"British Aerospace BAe 146 Series Aeropla","sectionType":"division","heading":"British Aerospace BAe 146 Series Aeroplanes","content":"### British Aerospace BAe 146 Series Aeroplanes\n\n| AD/BAe 146/127 | Hydraulic Power - Accumulator Cylinders | 5/2007 |\n| -------------- | --------------------------------------- | ------ |\n\n| Applicability: | BAe 146 and AVRO 146-RJ aeroplanes - All models.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | 1. Identify the installed hydraulic accumulator in accordance with paragraph 2C of BAe Systems Inspection Service Bulletin (ISB) 29-047 dated 3 October 2006, which makes reference to APPH Ltd. Service Bulletin (SB) AIR91666-29-03, dated July 2006, or later NAA approved revisions of these documents.2. When an accumulator is identified as being affected by this directive, remove the accumulator from service in accordance with paragraph 2D of BAe Systems ISB 29-047 and magnetic particle inspect the cylinder in accordance with APPH SB AIR91666-29-03.3. When any defects are found, replace the accumulator with a serviceable unit.4. Do not install an accumulator identified by APPH Ltd. SB AIR91666-29-03 on an aircraft, unless it has been inspected in accordance with APPH Ltd. SB AIR91666-29-02 or AIR91666-29-03 (See second Note in paragraph 1D(1) of ISB 29-047 for further explanation).Note: EASA AD 2007-0076 dated 21 March 2007 refers. |\n| Compliance:    | 1. Within 6 weeks after the effective date of this AD2. No later than 31 October 2009.3. Before further flight, after the effective date of this AD.4. After the effective date of this AD                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n|                | This Airworthiness Directive becomes effective on 10 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n| Background:    | A hydraulic accumulator cylinder had material defects and suffered an in-flight burst failure causing damage to the aircraft structure. This resulted in the issue of CASA telex AD/BAe146/119 requiring the identification and check of cylinders from known suspect batches. Further investigations and checks by the accumulator manufacturer have concluded that all cylinders from a particular supplier may not have been correctly inspected at manufacture.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\n\n|     | To prevent the risk of further failures, this AD requires all accumulators with cylinders from this supplier to be identified and inspected prior to re-installation. |\n| --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nCharles Lenarcic  \nDelegate of the Civil Aviation Safety Authority\n\n29 March 2007","sortOrder":0},{"sectionNumber":"AD/BAe 146/127","sectionType":"part","heading":"AD/BAe 146/127","content":"## AD/BAe 146/127","sortOrder":1},{"sectionNumber":"Hydraulic Power - Accumulator Cylinders","sectionType":"part","heading":"Hydraulic Power - Accumulator Cylinders","content":"## Hydraulic Power - Accumulator Cylinders","sortOrder":2},{"sectionNumber":"5/2007","sectionType":"part","heading":"5/2007","content":"## 5/2007","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a targeted safety intervention responding to a specific manufacturing defect. The scope remains precisely limited to hydraulic accumulator cylinders from one supplier on one aircraft family. No scope creep is evident."},"complexity_factors":["Short, single-purpose directive (4 numbered requirements)","Heavy reliance on external technical documents (2 service bulletins referenced but not reproduced)","Simple conditional logic: IF accumulator matches criteria → THEN inspect → IF defects found → THEN replace","No defined terms section — uses plain technical language","Clear compliance table mapping requirements to deadlines","Minimal cross-referencing (only to related EASA directive and previous CASA telex)"],"plain_english_summary":"This AD mandates that operators of BAe 146 and AVRO 146‑RJ aircraft inspect and, where required, remove and replace hydraulic accumulator cylinders from a specific supplier after a cylinder burst in flight revealed manufacturing/inspection failures. It affects any operator with those parts fitted and aims to prevent in‑flight catastrophic failure by requiring magnetic particle inspection, immediate replacement of defects, and prohibition on installing unchecked supplier units. Compliance windows range from six weeks up to 31 Oct 2009, with grounding if defects are found."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This AD expands and formalises earlier, narrower action. An earlier CASA telex (AD/BAe146/119) required identification and checks of cylinders from known suspect batches. This AD broadens the reach by requiring identification of all accumulators with cylinders from the implicated supplier (per ISB 29‑047), mandating a specific magnetic‑particle inspection procedure (per APPH SB AIR91666‑29‑03), prohibiting installation of accumulators unless inspected under the named APPH SBs, and setting explicit compliance deadlines. Mechanically, the scope moved from a limited batch check to a supplier‑wide inspection and an ongoing installation prohibition unless the inspection requirements are met."},"complexity_factors":["Short standalone AD with focused technical scope (single component type).","Several external cross‑references to manufacturer documents: BAe ISB 29‑047 and APPH SB AIR91666‑29‑03 and AIR91666‑29‑02.","Conditional sequence of steps (identify → remove → magnetic‑particle inspect → replace if defective → prohibition on installing uninspected units).","Multiple compliance time conditions (within 6 weeks; no later than a fixed calendar date; before further flight; immediate prohibition).","Dependence on definitions and procedures located in the referenced service bulletins (interpretation depends on those external texts).","Technical inspection requirement (magnetic‑particle) requiring specialist capability.","Reference to manufacturer/NAA approved revisions adds a moving‑parts element to compliance (must use latest approved revisions).","Minor interpretive ambiguity over which cylinders are \"from a particular supplier\" when traceability records are incomplete."],"plain_english_summary":"**What this instrument does (mechanically):**\n\n- **Which aircraft it covers:** All models of the British Aerospace BAe 146 and AVRO 146‑RJ aeroplanes.\n\n- **Actions required of operators / maintainers:**\n  - Identify hydraulic accumulators that have cylinders from the supplier and batches described in BAe Systems Inspection Service Bulletin (ISB) 29‑047, paragraph 2C (which refers to APPH Ltd. Service Bulletin AIR91666‑29‑03). (Action 1)\n  - If an accumulator is identified as affected, remove it from service (see ISB 29‑047 paragraph 2D) and perform a magnetic‑particle inspection of the cylinder in accordance with APPH SB AIR91666‑29‑03. (Action 2)\n  - If the inspection finds any defect, replace the accumulator with a serviceable unit before the aircraft is returned to flight. (Action 3)\n  - Do not install an accumulator that is identified by APPH SB AIR91666‑29‑03 on any aircraft unless it has been inspected in accordance with APPH SB AIR91666‑29‑02 or AIR91666‑29‑03. (Action 4)\n\n- **Timing / compliance windows:**\n  - Identify affected accumulators within 6 weeks of the AD becoming effective.\n  - Complete required inspections no later than 31 October 2009 (as set out in the AD's compliance column).\n  - Replace any defective unit before further flight after the AD takes effect.\n  - The prohibition on installing uninspected accumulators applies from the effective date of the AD. (The AD became effective 10 May 2007.)\n\n**Why the rule exists (stated rationale):**\n\n- The accumulator cylinder material had defects and an in‑flight burst occurred that damaged the airframe. Manufacturer investigations indicated cylinders from a particular supplier may not have been correctly inspected at manufacture. The AD implements mandatory identification and inspection to prevent further failures.\n\n**Who pays, who decides, and what behaviour changes:**\n\n- Operators / aircraft owners pay the direct costs: labour for identification and inspections, any magnetic‑particle testing fees, replacement parts and the opportunity cost of aircraft downtime.\n- Approved maintenance organisations perform the inspections and make the go/no‑go decisions for parts based on the referenced service bulletins. Civil Aviation Safety Authority (CASA) enforces compliance with the AD.\n- Behaviour changes required from operators: stop installing suspect accumulators unless inspected per the specified APPH service bulletins; remove and inspect suspect items; replace defective parts and schedule inspections within the specified windows.\n\n**Implementation details and control points:**\n\n- The AD delegates technical detail to the manufacturer service documents it references (BAe ISB 29‑047 and APPH SB AIR91666‑29‑03 / AIR91666‑29‑02). These documents define how to identify affected cylinders and how to carry out the magnetic‑particle inspection.\n- The prohibition on installation is immediate; actual identification and inspection activities follow the compliance timetable above.\n\n**Costs, incentives, trade‑offs and risks (practical assessment):**\n\n- Concentrated benefits: individual operators and passengers benefit from reduced risk of a repeat failure on affected aircraft. These benefits are concentrated on any operator that has affected accumulators.\n- Diffuse costs: all operators must absorb inspection and replacement costs and schedule aircraft out of service. Where a single supplier is implicated, operators may face constrained spare availability and higher replacement prices.\n- Compliance burden: operators must rely on authorised magnetic‑particle inspection capability and accurate records to establish whether a cylinder is from the supplier/batch in question; poor record keeping increases implementation cost and risk of unnecessary removals.\n- Bureaucratic discretion and clarity: the AD prescribes reliance on the named ISB/SBs; this reduces discretionary variation but places weight on how those documents define \"affected\" units. Ambiguity in traceability or in NAA approvals of revised SBs could complicate compliance.\n- Opportunity costs: aircraft out of service for inspection/repair reduce operator utilisation; some operators may choose to maintain larger spares inventories to reduce flight disruptions.\n- Substitution effects: the prohibition on installing uninspected accumulators may increase demand for inspected serviceable units or push operators to source alternative suppliers or overhauls.\n\n**Key references used by this AD:** BAe Systems ISB 29‑047 (3 October 2006) and APPH Ltd. Service Bulletins AIR91666‑29‑03 (July 2006) and AIR91666‑29‑02. The AD also refers to an EASA AD (2007‑0076) for related material.\n\n"},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-127-hydraulic-power-accumulator-cylinders","history":"/api/acts/ad-bae-146-127-hydraulic-power-accumulator-cylinders/history","analysis":"/api/acts/ad-bae-146-127-hydraulic-power-accumulator-cylinders/analysis","conflicts":"/api/acts/ad-bae-146-127-hydraulic-power-accumulator-cylinders/conflicts","importantCases":"/api/acts/ad-bae-146-127-hydraulic-power-accumulator-cylinders/important-cases","documents":"/api/acts/ad-bae-146-127-hydraulic-power-accumulator-cylinders/documents"}}