Airworthiness Directive · Amendment 39-13729 · The Cessna Aircraft Company Model 525 Airplanes
The Cessna Aircraft Company Model 525 Airplanes
This AD affects Model 525 airplanes with the following serial numbers that are certificated in any category:
(1) Group 1 (maintains the actions from AD 2003-21-07): 525-0001, 525-0002, and 525-0004 through 525-0159.
(2) Group 2: 525-0160 through 525-0359.
The FAA supersedes Airworthiness Directive (AD) 2003-21-07, which applies to certain The Cessna Aircraft Company (Cessna) Model 525 airplanes. AD 2003-21-07 currently requires you to disengage the pitch trim circuit breaker and AP servo circuit breaker and then tie strap each of them to prevent them from being engaged. Not utilizing this equipment prevents a single-point failure. This AD is the result of Cessna having now developed and made changes in the design of the affected trim printed circuit board (PCB) assembly to allow the use of the assembly and the prevention of the single-point failure, and identification of additional airplanes that have the same unsafe condition. Consequently, this AD requires you to remove and replace an old trim PCB assembly with a new design assembly or modify an old trim PCB assembly to the new design. We are issuing this AD to correct this single-point failure in the electric pitch trim system, which will result in a runaway pitch trim condition where the pilot could not disconnect using the control wheel autopilot/trim disconnect switch. Failure of the electric trim system would result in a large pitch mistrim and would cause excessive control forces that the pilot could not overcome.
To address this problem, you must do the following:
| Actions | Compliance | Procedures |
|---|---|---|
| (1) For Group 1 airplanes only: Disengage the PITCH TRIM circuit breaker located on the left circuit breaker panel. Install a tie strap (part number (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 | Within 5 calendar days or 10 hours time-in-service after October 22, 2003-21-07), whichever occurs first | Not Applicable. |
| (2) For Group 1 airplanes only: Disengage the AP SERVOS circuit breaker located in the right circuit breaker panel. Install a tie strap (P/N MS3367-1-4 or equivalent part number) on the shaft of the AP SERVOS circuit breaker from being engaged | Within 5 calendar days or 10 hours time-in-service after October 22, 2003 (the effective date of AD 2003-21-07), whichever occurs first | Not Applicable. |
| (3) The Minimum Crew portion of Section II—Operating Limitations of the Airplane Flight Manual (AFM) provides information on applicable operating limitations with the autopilot inoperable | Not Applicable | Not Applicable. |
| (4) All affected airplanes were originally equipped with a P/N 6518351-3 or P/N 65138351-5 Trim PCB Assembly. If a P/N 6518351-8 Trim PCB Assembly is installed, contact the Wichita Aircraft Certification Office at the address in paragraph (f) of this AD to determine if the installed P/N 6518351-8 Trim PCB assembly is an alternative method of compliance to this AD | Not Applicable | Not Applicable. |
| (5) Cessna Citation Alert Service Letter ASL525-27-02, dated October 10, 2003, contains information related to this subject | Not Applicable | Not Applicable. |
| (6) For both Group 1 and Group 2 airplanes: Do the trim PCB assembly change as follows: (i) Modify the 6518351-8 trim PCB assembly to a 6518351-10 trim PCB assembly; or (ii) Replace any 6518351-3 or 6518351-5 trim PCB assembly with a 6518351-10 (EX) trim PCB assembly. | Within the next 24 calendar months after August 23, 2004 (the effective date of this AD) or within 300 hours time-in-service (TIS) after August 23, 2004 (the effective date of this AD), whichever occurs first, unless already done | Follow the ACCOMPLISHMENT INSTRUCTIONS paragraph of Cessna Citation Service Bulletin No. SB525-27-17, dated December 9, 2003. |
| (7) For both Group 1 and Group 2 airplanes: Remove any tie strap (P/N MS3367-1-4 or equivalent part number) on the AP SERVOS and PITCH TRIM circuit breakers. (Required by AD 2003-21-07.) | Before further flight after the modification or replacement of the trim PCB assembly required by paragraph (e)(6)(i) or (e)(6)(ii) of this AD | Follow the ACCOMPLISHMENT INSTRUCTIONS paragraph of Cessna Citation Service Bulletin No. SB525-27-17, dated December 9, 2003. |
| (8) For both Group 1 and Group 2 airplanes: Do not install any 6518351-8, 6518351-3, or 6518351-5 trim PCB assembly | As of August 23, 2004 (the effective date of this AD) | Not Applicable. |
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
