{"id":"F2006B03905","name":"AD/BEECH 36/49 - KA-33 Cooling Blower","slug":"ad-beech-36-49-ka-33-cooling-blower","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43514,"registerId":"commonwealth-F2006B03905-current","compilationNumber":null,"startDate":"2026-04-02","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\nBeechcraft 36 (Bonanza) Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/BEECH 36/49 KA-33 Cooling Blower 8/20","sectionType":"part","heading":"AD/BEECH 36/49 KA-33 Cooling Blower 8/2001","content":"# AD/BEECH 36/49 KA-33 Cooling Blower 8/2001\n\nApplicability: Beech Model A36 aeroplanes, serial numbers E-2205 thorough E-3217 inclusive, and Model B36TC aeroplanes, serial numbers EA-443 through EA-628 inclusive.\n\nRequirement: 1. Inspect the aeroplane in accordance with Part I of the Accomplishment Instructions of Raytheon Mandatory Service Bulletin SB 34-3267, issued March 1999, to verify whether a KA-33 avionics cooling blower system is installed and operating correctly.\n\n    2. If the Requirement 1 inspection confirms that a KA-33 cooling blower is fitted, install a one ampere circuit breaker, part number 7277-2-1, in place of the factory installed three ampere or five ampere circuit breakers in accordance with Part II of the Accomplishment Instructions of SB 34-3267.\n\n    3. Three ampere or five ampere circuit breakers must not be installed on any aeroplane to protect the KA-33 cooling blower.\n\nNote: FAA AD 2001-11-03 Amdt 39-12244 refers.\n\nCompliance: For Requirement 1 - Within the next 600 hours time-in-service after the effective date of this Directive or the next six calendar months after the effective date of this Directive, whichever occurs first.\n\nFor Requirement 2 - Before further flight after the Requirement 1 inspection. For Requirement 3 - As of the effective date of this Directive.\n\nThis Airworthiness Directive becomes effective on 9 August 2001.\n\nBackground: The United States Federal Aviation Administration has received several reports of blower motors failing, seizing, smoking, and producing a burning odour that enters the cabin and passenger compartment. These events are the result of the blower motor having circuit protection of more than one ampere. This level of circuit protection does not prevent the blower motor from smoking and creating a burning odour should it fail or seize.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD is narrowly targeted to address a specific unsafe condition with KA-33 avionics cooling blowers on two defined blocks of Beechcraft serial numbers. It requires inspection and a single hardware change (install a specified 1A circuit breaker) and prohibits higher-rated breakers for that circuit. The requirements are consistent with the stated safety purpose (prevent smoke/burning odour from blower motor failures) and do not broaden the subject matter to other systems, aircraft, or regulatory domains. Therefore the scope has not significantly changed beyond the Directive’s original safety-focused purpose."},"complexity_factors":["Short document: three substantive requirements only","One main external technical reference: Raytheon Mandatory Service Bulletin SB 34-3267 (March 1999)","Single cross-reference to FAA AD 2001-11-03","Simple applicability: two contiguous serial-number ranges (A36: E-2205–E-3217; B36TC: EA-443–EA-628)","Three compliance time frames (inspect within 600 hours or 6 months; replace before further flight; prohibition effective immediately)","No dense defined-terms section or nested exceptions","Limited regulatory citation (CASA action under CAR 1998 subregulation 39.1(1))"],"plain_english_summary":"**What this directive does (mechanics)\n\n- Requires owners/operators of certain Beechcraft A36 and B36TC aeroplanes to check whether a KA-33 avionics cooling blower is fitted and working (Requirement 1).  The inspection must follow Part I of Raytheon Mandatory Service Bulletin SB 34-3267 (March 1999).\n- If a KA-33 blower is fitted, the directive requires replacing the existing circuit breaker (if it is a factory-fitted 3 ampere or 5 ampere unit) with a 1 ampere circuit breaker, part number 7277-2-1, following Part II of the same service bulletin (Requirement 2).\n- It prohibits using 3 ampere or 5 ampere circuit breakers to protect the KA-33 blower from the effective date onward (Requirement 3).\n\n**Who is affected\n\n- Owners/operators and maintenance organisations of Beechcraft Model A36 aeroplanes with serial numbers E-2205 through E-3217 inclusive, and Model B36TC aeroplanes with serial numbers EA-443 through EA-628 inclusive.  (See \"Applicability\".)\n- Maintenance providers who perform the inspection and replacement work per the Raytheon service bulletin.\n\n**When the work must be done\n\n- The inspection (Requirement 1) must be done within the earlier of: the next 600 hours time-in-service, or six calendar months after the Directive’s effective date.\n- If the inspection shows a KA-33 blower is fitted, the 1 ampere breaker must be installed before the aeroplane next flies.\n- From the effective date forward, 3A or 5A breakers must not be used to protect the KA-33 blower.\n\n**Why (official rationale)\n\n- The FAA reported several incidents where KA-33 blower motors failed, seized, smoked, and produced a burning odour in the cabin.  The investigations indicated that circuit protection rated at 3A or 5A did not prevent smoking or burning when the motor failed or seized.  The AD’s change to a 1A breaker is intended to provide earlier circuit protection to prevent smoke and burning odour entering the cabin.\n\n**Who pays and who decides\n\n- Aircraft owners/operators pay for the inspection, parts (the 1A circuit breaker, part no. 7277-2-1), and labour to fit it.  Costs are typically the cost of a small circuit breaker and a short shop visit.\n- CASA (the delegate acting under CAR 1998 subregulation 39.1(1)) enforces the AD; the inspection and replacement must follow the Raytheon service bulletin instructions.\n\n**Practical effects, compliance burden and risks\n\n- Compliance burden is procedural and modest: an inspection per the referenced service bulletin and, if applicable, replacement of a circuit breaker.\n- Implementation risk: the safety outcome depends on the inspection being done correctly and the correct breaker being fitted exactly as the service bulletin instructs.  Incorrect installation or failure to inspect leaves the unsafe condition unaddressed.\n- Operational trade-offs: installing a lower-rated (1A) breaker reduces allowable current to the blower circuit, which is intended to trip earlier if the motor seizes.  That could, in some circumstances, cause nuisance tripping if the blower’s normal inrush or running current approaches the new limit; the AD does not provide alternate mitigations beyond the breaker change.\n- Market effects: the directive imposes a small compliance cost on affected owners/operators and creates a short-term work opportunity for maintenance providers. It does not change ownership, competition, or contractual freedom except insofar as maintenance and parts must meet the AD and referenced service bulletin.\n\n**References and cross-checks\n\n- The AD requires following Raytheon Mandatory Service Bulletin SB 34-3267 (March 1999) for both inspection and installation instructions.\n- It also notes FAA AD 2001-11-03 as the associated U.S. action addressing the same problem.\n\n**Source-claimed purpose vs concrete mechanisms\n\n- The source claim: replacing 3A/5A breakers with a 1A breaker prevents blower motors from producing smoke and burning odour in the cabin should they fail or seize.\n- Concrete mechanism: lower-rated circuit protection should interrupt current sooner during a fault, limiting overheating or arcing in the blower motor. The measure’s effectiveness therefore depends on correct installation, correct breaker specification (7277-2-1), and that the motor’s normal operating/inrush current is below 1A so the breaker does not nuisance-trip. The AD addresses the unsafe condition by mandating inspection and a specific hardware change, shifting the compliance cost to aircraft owners/operators and maintenance providers."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific unsafe condition in specific aircraft. It has not expanded beyond its original purpose of preventing KA-33 cooling blower failures through incorrect circuit protection."},"complexity_factors":["Single, specific technical issue (circuit breaker sizing for one component)","Only two aircraft models affected with specific serial number ranges","Three straightforward requirements: inspect, replace if found, prohibition on old parts","Clear compliance deadlines with simple 'whichever comes first' logic","No nested definitions or cross-references to other legislation beyond a single FAA reference note","Total length is approximately one page"],"plain_english_summary":"This is a safety order for specific Beechcraft Bonanza aeroplanes. It requires owners to check if their plane has a particular avionics cooling fan (the KA-33). If it does, they must replace the existing circuit breaker with a smaller one-amp breaker. The old three or five amp breakers must never be used for this fan again. This prevents the fan motor from overheating, smoking, and creating burning smells in the cabin if it fails. Planes must be inspected within 600 flight hours or six months, and the fix must be done immediately if the fan is found."},"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-beech-36-49-ka-33-cooling-blower","history":"/api/acts/ad-beech-36-49-ka-33-cooling-blower/history","analysis":"/api/acts/ad-beech-36-49-ka-33-cooling-blower/analysis","conflicts":"/api/acts/ad-beech-36-49-ka-33-cooling-blower/conflicts","importantCases":"/api/acts/ad-beech-36-49-ka-33-cooling-blower/important-cases","documents":"/api/acts/ad-beech-36-49-ka-33-cooling-blower/documents"}}