{"id":"F2006B11373","name":"AD/MU-2/42 - Autopilot/Electric Trim Switch Standardisation","slug":"ad-mu-2-42-autopilot-electric-trim-switch-standardisation","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57274,"registerId":"commonwealth-F2006B11373-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/MU-2/42 - Autopilot/Electric Trim Switch Standardisation","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)  \nMitsubishi MU-2 Series Aeroplanes\n\nAD/MU-2/42 Autopilot/Electric Trim Switch Standardisation 13/89\n\nApplicability: All model MU 2 equipped with any manual electric trim system and/or any autopilot other than Bendix.\n\nRequirement: 1. Modify the control yoke in the affected model airplanes as follows:\n\n    For MU 2B-35 model aircraft equipped with a King KFC 300 automatic flight control system (AFCS) and a Sperry manual/electric pitch trim system, in accordance with Bendix/King Certification Bulletin No. CB10, KPN 006-0712- 00.\n\n    b. For MU 2B-36 model aircraft equipped with a Sperry SPZ-200 AFCS and a MAI manual/electric pitch trim system, in accordance with MHI Kit \\- Sperry SPZ-200AP Disengagement Drawing, 035A-985006.\n\n    2. Configuration check. Visually verify that:\n\n    The autopilot disconnect and trim disconnect/interrupt functions are combined on one button mounted on the outboard control wheel grip, and is so oriented that it is easily activated by the pilot/copilot.\n\n    b. The autopilot disconnect and trim disconnect/interrupt button is properly and legibly labelled to indicate functions.\n\n    c. The button is red in colour.\n\n    d. There are no other red buttons nearby that could be mistaken for the autopilot disconnect.\n\n    e. The autopilot circuit breaker is properly labelled.\n\n    3. Pitch Trim Disconnect/Interrupt Functional Check.\n\nWith the manual electric pitch trim system armed, press the trim button to cause the manual pitch trim wheel to rotate. Verify that when each of the following operations is performed, the manual pitch trim wheel stops moving:\n\n    disconnect/interrupt switch is fully depressed;\n\n    b. The master electric power switch is positioned to “OFF”;\n\n    c. The radio master switch is positioned to “OFF” (if installed and so configured); (not applicable to MU 2B aircraft equipped with Sperry SPZ-500 autopilots); or\n\n    d. The electric trim circuit breaker is pulled. (On some MU 2B aircraft without an electric trim circuit breaker, the autopilot circuit breaker/switch is used to disconnect the system in lieu of the electric trim circuit breaker.)\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n    4. Autopilot Disconnect Functional Check. With the autopilot system engaged, verify:\n\n    That the autopilot system can be overpowered by pushing or pulling on the control yoke; and\n\n    b. That, while overpowering the autopilot, the manual pitch trim wheel stops moving and the autopilot disconnects when each of the following operations is performed:\n\n    The disconnect/interrupt switch is depressed;\n\n    ii. The master electric power switch is positioned to “OFF”;\n\n    iii. The autopilot master switch or the radio master switch or the engage/disengage switch on the autopilot controller (as appropriate), is positioned to “OFF” (On some MU 2B aircraft not equipped with an autopilot master switch beside the controller, the radio master switch must be used to disconnect the system in lieu of the autopilot master switch.);\n\n    iv. The autopilot circuit breaker is pulled; or\n\n    v. When the “GA” go-around switch on the left power lever is depressed on MU 2B aircraft equipped with Sperry SPZ 500 autopilot.\n\nNote 1: It is very important that the manual pitch trim wheel stops moving after each of the operations of paras 3 or 4b is accomplished.\n\nNote 2: FAA AD 88-21-01 refers.\n\nCompliance: Prior to 31 March 1990.\n\nBackground: This AD resulted from a request by the National Transportation Safety Board (US) who while investigating a number of fatal MU 2B accidents, concluded that pilots were becoming confused in the operation of the interrupt/disconnect switches for the electric pitch trim and autopilot systems.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":false,"description":"The AD's scope matches its stated purpose: it targets all MU-2 aircraft with manual electric trim systems and/or non-Bendix autopilots and mandates specific modifications and checks to address NTSB-identified pilot confusion. The text sets installation, labelling and functional-test requirements for those aircraft; there is no indication within the instrument that its scope was broadened beyond that safety-focused intent (see Applicability; Requirement; Background)."},"complexity_factors":["Model-specific hardware modifications that reference external manufacturer documents (Requirement 1; Bendix/King Certification Bulletin No. CB10; MHI Kit - Sperry SPZ-200AP Disengagement Drawing, 035A-985006).","Multiple conditional functional checks depending on installed equipment (Configuration check paras 2; Pitch Trim Disconnect checks para 3; Autopilot Disconnect checks para 4).","Interdependence between different power/control items (master electric switch, radio master, autopilot master, circuit breakers, go-around switch) creates multiple failure/disconnect paths to verify (paras 3–4).","Safety-critical verification requires qualified personnel and the ability to simulate engaged autopilot and powered trim, increasing procedural and technical burden (paras 3–4).","Detailed labelling, colour and placement requirements to avoid confusion (para 2a–d) require cockpit access and possible rework of neighbouring controls.","Applicability limits (all MU-2 with manual electric trim and/or non-Bendix autopilot) create variation in which aircraft need which kit and checks (Applicability).","Compliance deadline imposes scheduling pressure on operators and maintenance providers (Compliance: Prior to 31 March 1990)."],"plain_english_summary":"This airworthiness directive requires owners/operators of affected Mitsubishi MU-2 aeroplanes to modify the control yoke so the autopilot disconnect and electric pitch-trim disconnect are combined on a single, red, clearly labelled outboard button, and to carry out prescribed configuration and functional checks. It references specific manufacturer bulletins/drawings for installation. The change responds to NTSB findings about pilot confusion; the compliance work and costs fall on aircraft owners/operators and must be done by 31 March 1990."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific identified hazard (pilot confusion with disconnect switches). The scope remains tightly focused on the original safety issue identified by the NTSB investigation."},"complexity_factors":["Multiple aircraft sub-models with different equipment configurations requiring different modification procedures (MU 2B-35 vs MU 2B-36)","Nested conditional requirements ('if installed and so configured', 'not applicable to...', 'On some MU 2B aircraft...')","Cross-reference to foreign regulation (FAA AD 88-21-01)","Technical aviation terminology throughout (AFCS, circuit breakers, pitch trim, etc.)","Detailed procedural testing requirements with multiple verification steps"],"plain_english_summary":"This Civil Aviation Safety Authority Airworthiness Directive requires Mitsubishi MU-2 operators to standardise the emergency autopilot/electric trim disconnect button — making it red, clearly labelled, mounted on the control wheel, isolated from other red controls, and testable — to prevent pilots pressing the wrong switch in emergencies.\n\nIt responds to US crash findings that such confusion caused fatal accidents; affected MU-2s (except those with Bendix autopilots) had to comply by 31 March 1990."}},"importantCases":[],"_links":{"self":"/api/acts/ad-mu-2-42-autopilot-electric-trim-switch-standardisation","history":"/api/acts/ad-mu-2-42-autopilot-electric-trim-switch-standardisation/history","analysis":"/api/acts/ad-mu-2-42-autopilot-electric-trim-switch-standardisation/analysis","conflicts":"/api/acts/ad-mu-2-42-autopilot-electric-trim-switch-standardisation/conflicts","importantCases":"/api/acts/ad-mu-2-42-autopilot-electric-trim-switch-standardisation/important-cases","documents":"/api/acts/ad-mu-2-42-autopilot-electric-trim-switch-standardisation/documents"}}