{"id":"F2006B08412","name":"AD/CESSNA 525/3 Amdt 1 - Electric Pitch Trim System","slug":"ad-cessna-525-3-amdt-1-electric-pitch-trim-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115873,"registerId":"commonwealth-F2006B08412-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 525/3 Amdt 1 - Electric Pitch Trim System","content":"![](image.001.png)\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CESSNA 525/3 and issues the following 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\nCessna 525 Series Aeroplanes\n\nAD/CESSNA 525/3\n\nAmdt 1\n\n  \n\nElectric Pitch Trim System 13/2003 TX\n\nApplicability: Model 525 aeroplanes, serial numbers 525- 0001, 525-0002 and 525-0004 through 525-0159 inclusive, without a Trim PC Board Assembly part number (P/N) 6518351- 8 installed.\n\nRequirement: 1. Unless previously accomplished, disengage the PITCH TRIM circuit breaker located on the left circuit breaker panel and install a tie strap (P/N MS3367-1- 4 or equivalent part number) on the shaft of the PITCH TRIM circuit breaker to prevent the circuit breaker from being engaged.\n\n2. Unless previously accomplished, disengage the AP SERVOS circuit breaker located in the right circuit breaker panel and install a tie strap (P/N MS3367-1-4 or equivalent part number) on the shaft of the AP SERVOS circuit breaker to prevent the circuit breaker from being engaged.\n\nNote 1: Installation of Trim PC Board Assembly P/N 6518351-8, in accordance with Cessna Citation Alert Service Letter ASL525-27-02, dated 10 October 2003, is considered an optional terminating action for Requirements 1 and 2 of this Directive.\n\nNote 2: The Minimum Crew portion of Section II \\- Operating Limitations of the Aircraft Flight Manual (AFM) provides information on applicable operating limitations with the autopilot inoperable.\n\nNote 3: FAA AD 2003-21-07 Amdt 39-13342 and FAA Wichita Aircraft Certification Office Alternate Method of Compliance (AMOC) letter dated 22 October 2003 refer.\n\nCompliance: For Requirements 1 and 2 - Remains unchanged as “Within 5 calendar days or 10 hours time-in-service after the effective date of the original issue of this Directive, whichever occurs first”.\n\nThis Amendment becomes effective on 27 October 2003.\n\nCessna 525 Series Aeroplanes\n\nAD/CESSNA 525/3 Amdt 1 (continued)\n\nBackground: Following an accident involving a Cessna Model 525 aeroplane where the pilot ditched the aeroplane in the water and reported a problem with the pitch trim system, the United States Federal Aviation Administration (FAA) and Cessna carried out an analysis of the pitch trim system. This analysis revealed the potential for a single- wire shorting to 28 volts or a failure of a relay in the electric pitch trim system such that the relay contacts remain closed and precludes disconnect of the pitch trim using the control wheel autopilot/trim disconnect switch.\n\nThe original issue of this Directive required the pitch trim circuit breaker and AP servo circuit breaker to be opened (disengaged) and tied to prevent them from being engaged. This action was designed to correct a single-point failure in the electric pitch trim system, which could result in a runaway pitch trim condition where the pilot could not disconnect using the control wheel autopilot/trim disconnect switch.\n\nThis Amendment introduces an optional terminating action to the opening (disengaging) of the circuit breakers.\n\nThe original issue of this Airworthiness Directive became effective on 24 October 2003.\n\n![Signature of Jim Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJim Coyne\n\nDelegate of the Civil Aviation Safety Authority 23 October 2003\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 27 October 2003.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment adds an optional terminating action—installation of Trim PC Board Assembly P/N 6518351-8 per Cessna Alert Service Letter ASL525-27-02—while retaining the original immediate requirement to disable and secure the PITCH TRIM and AP SERVOS circuit breakers and keeping the original compliance timeframe (Note 1; Requirement; Compliance)."},"complexity_factors":["Narrow applicability limited to specific serial numbers and absence of Trim PC Board P/N 6518351-8 (Applicability).","Simple, hardware-level required actions: disengage two circuit breakers and install tie straps on their shafts (Requirement 1 & 2).","Optional terminating action requires parts replacement (Trim PC Board P/N 6518351-8) and compliance with a Cessna Alert Service Letter (Note 1).","Short compliance window: within 5 calendar days or 10 hours time-in-service after the original directive (Compliance).","Cross-references to AFM operating limitations, FAA AD and AMOC letters add coordination and potential procedural checks (Notes 2 & 3).","Issued under subregulation 39.1(1) of CASR 1998 and revokes the prior AD, indicating administrative exercise of regulatory authority (intro/background).","Safety-critical technical root cause (single-wire short or relay failure leading to possible runaway trim) requires immediate operational and maintenance responses (Background)."],"plain_english_summary":"This Airworthiness Directive requires operators of specified Cessna 525 aeroplanes (certain serial numbers without Trim PC Board P/N 6518351-8) to disable the PITCH TRIM and AP SERVOS circuit breakers and secure them with tie straps to prevent re‑engagement. Compliance is within 5 calendar days or 10 hours time‑in‑service of the original directive.\n\nIt affects owners, pilots and maintenance providers because it addresses a potential runaway pitch‑trim failure identified after an accident. Installing Trim PC Board P/N 6518351-8 per the Cessna Alert Service Letter is offered as an optional terminating action."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 1 to an existing AD. The amendment stays within the original scope — addressing the same unsafe condition in the same aircraft population. It merely adds an optional terminating action (the circuit board upgrade) to the existing interim fix (tied-down circuit breakers). The scope has not expanded beyond the original electrical pitch trim safety issue."},"complexity_factors":["Single, specific aircraft model and narrow serial number range","Only 2 substantive requirements with clear physical actions (pull breakers, install tie straps)","One optional terminating action clearly identified","Minimal defined terms (only standard aviation abbreviations like P/N for part number)","No nested conditional logic or cross-references to other legislation","Straightforward compliance timeframe (5 days or 10 hours)","Background narrative explains the safety rationale in plain language"],"plain_english_summary":"This Australian AD orders owners/operators of specified Cessna 525 (certain serials lacking Trim PC Board P/N 6518351-8) to immediately secure—using cable ties—two circuit breakers (pitch trim and autopilot servos) within 5 days or 10 flight hours to prevent an electrical runaway pitch-trim condition that led to a ditching. Installing the upgraded Trim PC Board is an optional permanent fix that terminates the breaker restriction."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-525-3-amdt-1-electric-pitch-trim-system","history":"/api/acts/ad-cessna-525-3-amdt-1-electric-pitch-trim-system/history","analysis":"/api/acts/ad-cessna-525-3-amdt-1-electric-pitch-trim-system/analysis","conflicts":"/api/acts/ad-cessna-525-3-amdt-1-electric-pitch-trim-system/conflicts","importantCases":"/api/acts/ad-cessna-525-3-amdt-1-electric-pitch-trim-system/important-cases","documents":"/api/acts/ad-cessna-525-3-amdt-1-electric-pitch-trim-system/documents"}}