2003-21-07 THE CESSNA AIRCRAFT COMPANY:
Amendment 39-13342; Docket No. 2003-CE-46-AD.

Airworthiness Directives; The Cessna Aircraft Company Model 525 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for certain The Cessna Aircraft Company (Cessna) Model 525 airplanes. This AD 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. This AD is the result of analysis that reveals 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. 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.

DATES: This AD becomes effective on October 22, 2003.

What Airplanes Are Affected by This AD?
   (c)    This AD affects Model 525 airplanes, serial numbers 525-0001, 525-0002, and 525-0004 through 525-0159, that are certificated in any category.

What Is the Unsafe Condition Presented in This AD?
(d)    This AD is the result of analysis that reveals 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. 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.