{"id":"F2006B11391","name":"AD/MU-2/61 Amdt 1 - Trim In Motion and Automatic Pilot Disconnect System","slug":"ad-mu-2-61-amdt-1-trim-in-motion-and-automatic-pilot-disconnect-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57292,"registerId":"commonwealth-F2006B11391-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/MU-2/61 Amdt 1 - Trim In Motion and Automatic Pilot Disconnect System","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)  \n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/MU-2/61 and issues the following 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\nMitsubishi MU-2 Series Aeroplanes\n\nAD/MU-2/61\n\nAmdt 1\n\n  \n\nTrim In Motion and Automatic Pilot Disconnect System\n\n  \n7/2001\n\nApplicability: Mitsubishi Model MU-2B, MU-2B-10, -15, -20 and -25 aircraft having serial numbers 008 through 279 inclusive; and MU-2B-30, \\-35 and \\-36 airplanes having\n\nserial numbers 502 through 651 inclusive, and 653.\n\nRequirement: Unless previously accomplished in accordance with Mitsubishi MU-2 Service Bulletin (SB) No.231 dated 2 July 1997, install a trim-in-motion alert system and an automatic autopilot disconnect system in accordance with. Mitsubishi MU-2 SB No.231A dated 20 December 2000.\n\nNote 1: There is a flight manual revision associated with this installation. Note 2: Japanese Civil Aviation Bureau AD TCD-4625A-2001 refers.\n\nCompliance: Before 1 December 2001.\n\nThis Amendment becomes effective on 12 July 2001.\n\nBackground: The original issue of this Directive was issued to minimise the risk of undetected airspeed decreasing during flight with autopilot engaged in icing conditions, which could result in the aircraft stalling. Reports had been received by the manufacturer that pilots have inadvertently allowed their aircraft to slow while climbing or in cruise with the autopilot engaged in an attitude or altitude hold mode.\n\nThis amendment introduces an additional aeroplane model and an alternative method of compliance.\n\nThe original issue of this Directive became effective on 4 December 1997.\n\n![Signature of Eugene Paul Holzapfel Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 30 May 2001\n\n![](image.001.png)\n\nThe above AD is notified in the Commonwealth of Australia Gazette on 13 June 2001.\n\n  \nPage 1 of 1","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment stays true to the original purpose of preventing autopilot-related stall incidents in icing conditions. The changes are minor: adding one additional aircraft serial number and referencing an updated service bulletin as an alternative compliance method. The core safety objective and regulatory scope remain unchanged."},"complexity_factors":["Single-page document with straightforward structure (Applicability, Requirement, Compliance, Background)","Only 3 defined references (Service Bulletin 231, Service Bulletin 231A, and Japanese Civil Aviation Bureau AD TCD-4625A-2001)","No nested conditional logic — simple 'unless already done, you must install' requirement","Limited cross-referencing — only refers to manufacturer's service bulletins and one foreign aviation directive","Clear, unambiguous compliance deadline with no exceptions or alternative compliance methods detailed in the text itself"],"plain_english_summary":"This CASA safety order requires owners of certain Mitsubishi MU-2B aircraft to install a trim‑in‑motion warning and an automatic autopilot disconnect to prevent unrecognised airspeed decay and possible stall when autopilot masks control issues in icing. It applies to specific serial-number ranges (1960s–early 1980s production), had a compliance deadline of 1 December 2001, and this version adds one serial (653) and an alternative means of compliance."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment makes limited, specific changes to the original AD: it adds one additional aeroplane model/serial range and recognises an alternative method of compliance. These are narrow extensions that preserve the original safety objective (preventing undetected airspeed decay with autopilot engaged in icing conditions) rather than expanding the AD's purpose or introducing new regulatory aims."},"complexity_factors":["Short, single-page AD with limited provisions","Applicability restricted to specific MU-2 models and serial number ranges (several discrete ranges to check)","One primary operational condition and remedial action (install two systems)","References an external detailed compliance document (Mitsubishi MU-2 SB No.231A) that contains technical steps","Conditional language: \"Unless previously accomplished in accordance with SB No.231\" (creates an exception)","Notes require a flight manual revision (additional administrative step)","Cross-reference to a foreign (Japanese) AD for related context","Introduces an alternative method of compliance (adds some choice and minor complexity)"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This Airworthiness Directive (AD) orders operators of certain Mitsubishi MU-2 aeroplanes to install two safety systems: a \"trim-in-motion\" alert and an automatic autopilot disconnect system. The installation must follow the manufacturer's Service Bulletin (Mitsubishi MU-2 SB No.231A dated 20 December 2000) unless the earlier SB No.231 (2 July 1997) has already been complied with. (Requirement)\n- The AD applies only to specific MU-2 models and serial number ranges listed in the AD. (Applicability)\n- Operators must complete the work by 1 December 2001. A flight manual revision is required as part of the installation. (Compliance and Note)\n- The AD was issued because of reports that in icing conditions pilots have inadvertently allowed airspeed to decrease while the autopilot was engaged in altitude or attitude hold, increasing the risk of a stall. The AD aims to reduce that risk by alerting crews to trim movement and by disconnecting the autopilot when the trim condition occurs. (Background)\n\n**Who this affects**\n\n- Owners and operators of the listed Mitsubishi MU-2 models and serial numbers. They are responsible for scheduling and paying for the modification, arranging approved maintenance, and updating the aircraft flight manual. (Applicability; Requirement; Note)\n- Maintenance organisations and technicians who must install the equipment to the manufacturer's Service Bulletin standard.\n\n**Why it matters (stated purpose and practical effect)**\n\n- Stated purpose: to reduce the chance of an undetected airspeed decrease while the autopilot is engaged in icing conditions, which can lead to a stall. (Background)\n- Practical effect: once installed, the aircraft will give a crew alert when trim moves unexpectedly and will automatically disconnect the autopilot in specified conditions. This changes cockpit indications and autopilot behaviour, forcing a pilot to fly manually or take corrective action when the condition arises. (Requirement; Note)\n\n**Costs, incentives and trade-offs (mechanical and organisational consequences)**\n\n- Direct costs: parts, labour, downtime for installation, and the administrative cost of updating flight manuals. These are borne by the aircraft owners/operators. (Requirement; Compliance; Note)\n- Operational impact: potential for increased manual flying if the autopilot disconnects; possible nuisance disconnects could impose recurrent pilot workload. The AD allows an alternate compliance method (introduced by the amendment), which can affect the cost and method of meeting the requirement. (Background)\n- Implementation risk: depends on availability of parts, the experience of maintenance providers, and correct adherence to the referenced Service Bulletin. Improper installation or incomplete flight manual updates would undermine the intended safety benefit. (Requirement; Note)\n- Incentives: Operators are incentivised to comply before the deadline to remain airworthy and legal to operate; alternative compliance paths offer some flexibility in how to meet the mandate. (Requirement; Background)\n\n**Who pays, who decides, and what behaviour changes**\n\n- Who pays: aircraft owners/operators pay for installation, maintenance and the flight manual revision. (Requirement; Note)\n- Who decides: the Civil Aviation Safety Authority (through its delegate) mandates the AD and sets the compliance date; operators choose when and where to have the work done, subject to meeting the Service Bulletin instructions or an approved alternative. (Prefatory paragraph; Requirement)\n- Behaviour changes: pilots will receive a new trim-in-motion alert and may experience autopilot disconnects under the conditions the system detects; maintenance organisations must perform the SB installation and update manuals. (Requirement; Note)\n\n**Sources and cross-references**\n\n- The AD requires compliance with Mitsubishi MU-2 SB No.231A (20 Dec 2000) unless the earlier SB No.231 (2 Jul 1997) has already been done. It also notes a related Japanese Civil Aviation Bureau AD (TCD-4625A-2001). (Requirement; Note)\n\n**Analyst's practical appraisal (short)**\n\n- The measure is narrowly targeted: it mandates a specific retrofit on a defined set of aircraft to address a specific aerodynamic safety risk. The main burdens are direct retrofit cost and possible increased manual workload if the autopilot disconnects. The amendment adds one model and an alternative compliance route; it does not materially broaden the AD's safety objective.\n"},"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-mu-2-61-amdt-1-trim-in-motion-and-automatic-pilot-disconnect-system","history":"/api/acts/ad-mu-2-61-amdt-1-trim-in-motion-and-automatic-pilot-disconnect-system/history","analysis":"/api/acts/ad-mu-2-61-amdt-1-trim-in-motion-and-automatic-pilot-disconnect-system/analysis","conflicts":"/api/acts/ad-mu-2-61-amdt-1-trim-in-motion-and-automatic-pilot-disconnect-system/conflicts","importantCases":"/api/acts/ad-mu-2-61-amdt-1-trim-in-motion-and-automatic-pilot-disconnect-system/important-cases","documents":"/api/acts/ad-mu-2-61-amdt-1-trim-in-motion-and-automatic-pilot-disconnect-system/documents"}}