{"id":"F2005L03580","name":"AD/BAe 146/118 - Left Control Cable Duct at Frame 12 and Toilet Bulkhead Structure","slug":"ad-bae-146-118-left-control-cable-duct-at-frame-12-and-toilet-bulkhead-structure","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":39168,"registerId":"commonwealth-F2005L03580-current","compilationNumber":null,"startDate":"2026-04-01","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 146/118 | Left Control Cable Duct at Frame 12and Toilet Bulkhead Structure | 13/2005 |\n| -------------- | ---------------------------------------------------------------- | ------- |\n\n| Applicability: | All Models BAe 146 and AVRO 146-RJ series aircraft with Service Bulletin25-436-50303C installed.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. For aircraft with Service Bulletin 25-436-50303C installed:Carry out the modification to the control cable duct in accordance with Paragraph 2, Part 1 of Service Bulletin 25-459-36241A initial issue, or later EASA approved revision.2. For aircraft with Service Bulletin 25-436-50303C installed and which also have a toilet unit installed under modification HCM30033E or HCM30033F or HCM30033G or HCM30033N at the forward left position:Carry out the modifications to the control cable duct and toilet bulkhead structure in accordance with Paragraph 2, Part 1 and Part 2 of Service Bulletin25-459-36241A initial issue, or later EASA approved revision.Note: UK CAA AD G-2005-0026 refers. |\n| Compliance:    | Before 30 June 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\n|                | This Airworthiness Directive becomes effective on 22 December 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n| Background:    | Under certain conditions, if a Windscreen A Panel were to fail causing a rapid decompression and the flight deck door were in a closed position, the resultant differential pressure between the flight deck and cabin could result in deformation of the flight deck bulkhead at Frame 12 and the cable duct attached to it. This duct protects the primary flying control cables that run in this area and any deformation could result in the duct contacting these cables, leading to restriction of the primary flying controls.                                                                                                                                                                           |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n8 November 2005","sortOrder":0},{"sectionNumber":"AD/BAe 146/118","sectionType":"part","heading":"AD/BAe 146/118","content":"## AD/BAe 146/118","sortOrder":1},{"sectionNumber":"Left Control Cable Duct at Frame 12and T","sectionType":"part","heading":"Left Control Cable Duct at Frame 12and Toilet Bulkhead Structure","content":"## Left Control Cable Duct at Frame 12  \nand Toilet Bulkhead Structure","sortOrder":2},{"sectionNumber":"13/2005","sectionType":"part","heading":"13/2005","content":"## 13/2005","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a targeted airworthiness directive addressing a specific safety defect identified in the background section. The scope remains precisely focused on the control cable duct and toilet bulkhead modifications necessary to prevent flight control restriction following rapid decompression events. No evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Short, single-purpose directive with only 2 main requirements","Conditional applicability based on specific Service Bulletin installation (SB 25-436-50303C)","Nested condition for second requirement (toilet unit installed under specific modification numbers HCM30033E/F/G/N)","Cross-reference to external technical document (Service Bulletin 25-459-36241A) for actual implementation details","Reference to equivalent UK aviation safety directive (G-2005-0026)","Minimal defined terms (relies on aircraft industry standard terminology)","Clear compliance date and effective date"],"plain_english_summary":"This CASA Airworthiness Directive mandates modifications to the control-cable duct at Frame 12 — and, where a forward-left toilet is installed, the toilet bulkhead — on certain BAe 146 and AVRO 146‑RJ aircraft with SB 25‑436‑50303C. It prevents cable jamming from wall deformation during rapid decompression. Operators must carry out the work per Service Bulletin 25‑459‑36241A (or later approved) by 30 June 2006."},"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD stays within the original safety purpose: to prevent deformation of the Frame 12 bulkhead and cable duct that could restrict primary flight controls after a windsreen A panel failure (Background). It targets a specific subset of the BAe 146/AVRO 146‑RJ fleet (those with SB 25‑436‑50303C installed) and adds a narrowly defined extra requirement only where a particular toilet modification is present (Requirement). It therefore does not materially broaden the legislation beyond its stated hazard‑mitigation purpose."},"complexity_factors":["Narrow, focused subject matter limited to one structural area (left control cable duct at Frame 12) and an associated toilet bulkhead when a specific toilet modification is present","Single clear compliance deadline (30 June 2006) and effective date (22 December 2005)","Conditional requirement branches: baseline modification for aircraft with SB 25‑436‑50303C; additional work only if toilet mod HCM30033E/F/G/N is present","Cross‑reference to specific service bulletins (SB 25‑459‑36241A) and allowance for later EASA‑approved revisions","Reference to another regulator's AD (UK CAA AD G‑2005‑0026) but no multiple layers of exceptions or complex definitions","No extensive definitions section or numerous statutory exceptions","Technical dependency on external documents (service bulletins) increases practical complexity for implementers but not legal textual complexity"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- This Airworthiness Directive (AD) orders operators of certain BAe 146 / AVRO 146‑RJ aeroplanes to modify the left control cable duct at fuselage Frame 12.  If the aeroplane also has a specific forward‑left toilet installation, it also requires modifications to the toilet bulkhead structure.  The work must be done exactly as set out in Service Bulletin 25‑459‑36241A (Part 1 for the duct; Part 2 additionally for the toilet bulkhead) or a later revision approved by EASA.  (See: Requirement, Applicability.)\n\n- The AD applies only to aircraft that already have Service Bulletin 25‑436‑50303C installed; among those, a subset that also has a forward‑left toilet installed under modification HCM30033E/F/G/N must have the additional toilet‑bulkhead work.  (See: Applicability, Requirement.)\n\n- The AD sets a compliance deadline: the required modification must be completed by 30 June 2006. The AD became effective on 22 December 2005.  (See: Compliance.)\n\nWhy the AD was issued (stated risk)\n\n- The paperwork explains that if a windsreen A panel fails and the flight deck door is closed, a rapid decompression can create a pressure difference that deforms the flight‑deck bulkhead at Frame 12 and the cable duct attached to it.  That deformed duct can contact the primary flying control cables that run inside it and restrict primary flight controls.  The AD therefore mandates structural changes to avoid that failure mode.  (See: Background.)\n\nWho is affected and who pays\n\n- Affected parties: operators and owners of BAe 146 / AVRO 146‑RJ aeroplanes that have Service Bulletin 25‑436‑50303C installed. If the forward‑left toilet modification (HCM30033E/F/G/N) is also present, additional work is required.\n\n- Who pays: aircraft operators/owners pay for the engineering work, parts, and any aircraft downtime required to carry out the service‑bulletin modifications. Maintenance organisations doing the work must follow the SB instructions and any applicable regulatory approvals.\n\nWhat the AD changes about how operators must behave\n\n- Operators of affected aircraft must schedule and complete the mandated structural modifications by the deadline or the aircraft will not meet the AD (and thus are not airworthy for normal operations).  The AD allows following later EASA‑approved revisions of the cited service bulletin, giving some procedural flexibility on the exact method so long as it has the regulator's approval.  (See: Requirement.)\n\nPurpose claims and an analyst's test of trade‑offs, costs and incentives\n\n- Purpose claim: the AD is designed to reduce the risk that decompression plus a closed flight deck door deforms the Frame 12 bulkhead and compromises flight controls.  This is an engineering‑risk mitigation measure (Background).\n\n- Direct costs and who bears them: costs are concentrated on owners/operators of the affected fleet (parts supply, labour, and aircraft out‑of‑service time). There are no new ongoing fees; this is a one‑off retrofit obligation tied to a safety hazard. (See: Requirement, Compliance.)\n\n- Productivity and opportunity cost: aircraft will be unavailable while modified, which affects scheduling and revenue for operators. Smaller operators with fewer spares may face proportionally higher disruption.\n\n- Competition and private choice: the AD does not alter market rules or ownership; it imposes a uniform technical standard on affected aircraft. Operators cannot contract around the AD for commercial flights: compliance is a regulatory requirement for airworthiness.\n\n- Implementation risk and compliance burden: the AD references a specific service bulletin (25‑459‑36241A) and permits later EASA‑approved revisions. The quality of the outcome depends on competent maintenance organisations, availability of parts, and correct interpretation of the SB. Misapplication of the SB or poor workmanship could leave the risk unmitigated.\n\n- Bureaucratic discretion and interactions with other regulators: the AD accepts later EASA‑approved revisions and notes a related UK CAA AD, creating a cross‑jurisdictional influence on acceptable corrective action. That reduces some regulatory uncertainty but requires operators to track approvals. (See: Requirement, Note.)\n\n- Concentrated benefits vs diffuse costs: the immediate safety benefit accrues to passengers and crew (diffuse beneficiaries), while the compliance cost is concentrated on the operators of these specific aircraft. That allocation is typical for ADs addressing specific fleet risks.\n\n- Substitution and unintended effects: operators may need to reschedule flights or use other aircraft; small operators with older fleets could incur larger marginal costs or retire affected airframes sooner than planned.\n\nPractical takeaways\n\n- If you operate an affected BAe 146 / AVRO 146‑RJ with SB 25‑436‑50303C installed, arrange for the duct modification (and the additional toilet bulkhead work if you have the specified toilet mod) per SB 25‑459‑36241A or an EASA‑approved later revision no later than 30 June 2006. The AD is binding for airworthiness purposes and non‑compliance affects the aircraft's legal ability to operate. (See: Applicability, Requirement, Compliance.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-118-left-control-cable-duct-at-frame-12-and-toilet-bulkhead-structure","history":"/api/acts/ad-bae-146-118-left-control-cable-duct-at-frame-12-and-toilet-bulkhead-structure/history","analysis":"/api/acts/ad-bae-146-118-left-control-cable-duct-at-frame-12-and-toilet-bulkhead-structure/analysis","conflicts":"/api/acts/ad-bae-146-118-left-control-cable-duct-at-frame-12-and-toilet-bulkhead-structure/conflicts","importantCases":"/api/acts/ad-bae-146-118-left-control-cable-duct-at-frame-12-and-toilet-bulkhead-structure/important-cases","documents":"/api/acts/ad-bae-146-118-left-control-cable-duct-at-frame-12-and-toilet-bulkhead-structure/documents"}}