{"id":"F2006B03929","name":"AD/BEECH 400/26 - Spoiler Mixer Bay Drain Holes","slug":"ad-beech-400-26-spoiler-mixer-bay-drain-holes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43538,"registerId":"commonwealth-F2006B03929-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\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 CASR 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\nBeechcraft 400 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/BEECH 400/26 Spoiler Mixer Bay Drain ","sectionType":"part","heading":"AD/BEECH 400/26 Spoiler Mixer Bay Drain Holes 1/2005","content":"# AD/BEECH 400/26 Spoiler Mixer Bay Drain Holes 1/2005\n\nApplicability: Model 400, 400A, and 400T series aircraft.\n\nRequirement: 1. Accomplish a visual inspection of the spoiler mixer bay panels to determine the presence of drain holes, in accordance with the Accomplishment Instructions of Raytheon Service Bulletin SB 53-3486, dated June 2003. Following the inspection, before further flight, drill at least one new drain hole, and any additional drain holes needed.\n\n2. Accomplish a visual inspection for discrepancies of the sealant on the relief cutout on the aft pressure bulkhead, and of the small triangular-shaped baffles at left butt line BL 19.13 and right butt line BL 10.43; in accordance with SB\n\n53-3486. Accomplish any applicable corrective actions before further flight.\n\nNote: FAA AD 2004-22-02 Amdt 39-13830.\n\nCompliance: Within 400 flight hours or 12 months after 20 January 2005, whichever occurs first.\n\nThis Airworthiness Directive becomes effective on 20 January 2005.\n\nBackground: The FAA received a report of fuel leaking from components in the spoiler mixer bay of several Model 400A series aircraft. The accumulation of fuel and/or fuel vapour in the spoiler mixer bay and/or the aft fuselage compartment could result in a fire in the aircraft.\n\n![Signature: David Villiers](image.002.png)  \n\nDavid Villiers\n\nDelegate of the Civil Aviation Safety Authority 30 November 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 22 December 2004.","sortOrder":1}],"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD is narrowly focused on correcting a specific unsafe condition (fuel leakage and potential fuel accumulation in the spoiler mixer bay/ aft fuselage) on specified Beechcraft 400-series models. The measures (inspect, drill drain hole(s), check sealant and baffles, and repair) align with that stated purpose. It does not expand the scope beyond those aircraft or beyond remedial inspections and repairs related to that condition."},"complexity_factors":["Short, single-topic AD (two primary inspection/corrective actions)","Applies to a limited set of models (Model 400, 400A, 400T)","One compliance window (400 flight hours or 12 months) — simple conditional timing","References an external technical document (Raytheon Service Bulletin SB 53-3486) which contains the detailed procedures","Cross-reference to FAA AD 2004-22-02 noted, but no layered exceptions or multiple compliance tracks"],"plain_english_summary":"**What this rule does**\n\n- This Airworthiness Directive (AD) requires owners/operators of certain Beechcraft 400-series aeroplanes to inspect parts of the spoiler mixer bay and aft fuselage area, fix any problems found, and add at least one drain hole if drain holes are missing. The specific work must follow the instructions in Raytheon Service Bulletin SB 53-3486 (June 2003).\n\n**Who it applies to**\n\n- Applies to Beechcraft Model 400, 400A and 400T series aircraft (see \"Applicability\").\n\n**What you must do, mechanically**\n\n- Requirement 1: Visually inspect the spoiler mixer bay panels to see if drain holes exist (follow Raytheon SB 53-3486). If drain holes are missing, drill at least one new drain hole (and more if needed) before the aeroplane flies again.\n- Requirement 2: Visually inspect the sealant around the relief cutout on the aft pressure bulkhead and inspect two small triangular-shaped baffles at specified butt line locations for any discrepancies (again, follow SB 53-3486). Fix any defects before further flight.\n- Compliance deadline: complete the work within 400 flight hours or 12 months after 20 January 2005, whichever comes first. The AD becomes effective 20 January 2005.\n\n**Why it matters (stated reason and practical effect)**\n\n- The AD was issued because fuel leaks had been reported around components in the spoiler mixer bay on Model 400A aircraft. Fuel pooling or vapour accumulation in the spoiler mixer bay or aft fuselage could create a fire hazard. The mechanical effect of the AD is to reduce the chance that fuel will collect in those compartments by ensuring drain holes exist and that sealant and baffles are intact.\n\n**Who pays and who decides**\n\n- Aircraft owners/operators bear the cost (inspection time, drilling, repairs, parts, and any downtime). The CASA delegate imposed the requirement under subregulation 39.1(1) of CASR 1998 and directs compliance with the Raytheon service bulletin.\n\n**Implementation notes, trade-offs and operational impact**\n\n- This is a one-time inspection and corrective action per aircraft (not recurring unless future ADs require it). The main costs are labour and possible short-term grounding for the work.\n- The instruction to follow Raytheon SB 53-3486 means operators must obtain and follow that service bulletin; actions must be carried out by personnel authorised to perform structural/airworthiness maintenance. Improper drilling or repairs could damage structure or create other maintenance problems, so adherence to the SB is important.\n- The AD creates demand for maintenance work for approved maintenance organisations; operators incur direct costs but receive the concentrated benefit of reduced fire risk for the affected aircraft.\n\n**Source claim vs consequences**\n\n- The AD’s stated purpose (prevent fire risk from fuel accumulation) is explicit in the Background. That purpose trades an upfront, per-aircraft maintenance cost and some downtime for reduced risk of fuel-related fire. The requirement is targeted and procedural (inspect, drill, repair), leaving little regulatory discretion beyond enforcing compliance and referencing the service bulletin for technical detail.\n\n(References in the AD: \"Requirement\" paragraphs 1 and 2; \"Compliance\" paragraph; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope — addressing a specific unsafe condition (fuel accumulation) in specific aircraft models. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (approximately 250 words)","Only 2 main requirements with clear sequential steps","Single applicability criterion (specific aircraft models)","Simple compliance trigger (flight hours OR calendar date)","Minimal defined terms (only standard aviation references like 'butt line' which are industry-standard measurements)","No nested exceptions or conditional logic","Direct reference to only one external technical document (Raytheon Service Bulletin SB 53-3486)"],"plain_english_summary":"This CASA safety order affects Beechcraft Model 400, 400A and 400T aeroplanes and requires owners/operators to inspect and modify the spoiler mixer bay to prevent fuel entering that compartment. It mandates checking and adding drain holes, inspecting and repairing sealant on the aft pressure bulkhead and triangular baffles, and fixing defects before further flight. It’s a fire‑prevention measure with a compliance window tied to 400 flight hours or 12 months from 20 Jan 2005."}},"importantCases":[],"_links":{"self":"/api/acts/ad-beech-400-26-spoiler-mixer-bay-drain-holes","history":"/api/acts/ad-beech-400-26-spoiler-mixer-bay-drain-holes/history","analysis":"/api/acts/ad-beech-400-26-spoiler-mixer-bay-drain-holes/analysis","conflicts":"/api/acts/ad-beech-400-26-spoiler-mixer-bay-drain-holes/conflicts","importantCases":"/api/acts/ad-beech-400-26-spoiler-mixer-bay-drain-holes/important-cases","documents":"/api/acts/ad-beech-400-26-spoiler-mixer-bay-drain-holes/documents"}}