(f)
Test 5 - Disengage Synchronization
1) The yaw damper is disengaged, hydraulics are turned off and GO is pressed. A stimulus is applied to input 3 at the valve amplifier. The valve amplifier output is synchronized and the integrator output read at 1. Test time is approximately 5 seconds.
(g)
Test 6 - Derived Acceleration First Stage
1) The yaw damper is disengaged, hydraulics are turned off, and GO is pressed. The stimulus at input 3 is removed and a 10v dc stimulus is applied to input 4 at the demodulation amplifier. The derived acceleration output is read at 6. Test time is approximately 1 second.
(h)
Test 7 - Rate Gyro Filter 2
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1) The yaw damper is disengaged, hydraulics are turned OFF, and GO is pressed. The stimulus at input 4 is removed and a 10v dc stimulus is applied to input 5 at the airspeed gain circuit and airspeed gain is read at 7. Test time is approximately 1 second.
(I) Test 8 - Rate Gyro 1) The yaw damper is disengaged, hydraulics are off and GO is pressed. The stimulus at input 3 is removed and the rate gyro is torqued. The rate gyro demodulator output is read at 2. Test time is approximately 1 second. Torquing stimulus is removed from the rate gyro at the end of the test.
2) The BITE switch is returned to OFF at the end of the tests. Hydraulics are applied and the yaw damper coupler is engaged for normal operation. AUTOPILOT AND YAW DAMPER SYSTEM - TROUBLE SHOOTING
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EFFECTIVITY
GJ ALL EXCEPT B-2509 and B-2510
1. General
A. The following trouble shooting procedures are intended to help trouble shoot the yaw damper system and autopilot system down to a component level. Trouble shooting charts are based on possible failure reports which may occur and the corresponding isolation procedure to detect and replace the faulty component. The charts are listed under the system heading and are separated into engage problems or operational problems.
B. Yaw Damper System (All except coupler P/N 4084042)
NOTE: For aircraft with coupler P/N 4084042 installed (incorporating SB 27A1206), see 22-12-01.
(1)
Trouble shooting the yaw damper system operational faults can be accomplished fairly quickly through use of the system test circuits. The yaw damper test switch on the center instrument panel torques the rate gyro in the yaw damper coupler. With hydraulic and electrical power on and the system engaged, a complete check of the system is made as indicated on the yaw damper indicator on the center instrument panel and observed rudder movement. If the system is faulty, the yaw damper coupler is usually at fault. The yaw damper coupler has a self-test or BITE switch on the front panel. Operation of the self-test switch or performing BITE sequence checks the majority of the signal paths in the system (Ref Autopilot and Yaw Damper System - Adjustment/Test). Proper analysis of the self-test readings, while performing a self-test, or BITE failure analysis after completion of BITE sequence, helps indicate whether the coupler is at fault or a fault is at the rudder hydraulic power pack (Ref Yaw Damper System Operation Trouble Shooting Charts). It should be noted that the autopilot warning lights illuminate steadily if a self-test or BITE switch on the yaw damper coupler (and roll channel or pitch channel) is in any position other than off or if the rate gyro switch on the coupler (when installed) is operated.
CAUTION: OPERATION OF THE YAW DAMPER TEST SWITCH AND THE RATE GYRO TEST SWITCH ON THE COUPLER MUST BE LIMITED TO 10 SECONDS OR LESS TO PREVENT OVERHEATING OF THE RATE GYRO TORQUING COILS. TEST SWITCH MAY BE OPERATED AGAIN AFTER ALLOWING RATE GYRO TO COOL FOR APPROXIMATELY 1 MINUTE.
(2)
Trouble shooting yaw damper system engage faults involves checking the operation of the autopilot accessory box, autopilot switching accessory box (when installed) and yaw damper coupler. If the yaw damper system does not engage or has nuisance trips, the fault will probably be in one of the accessory boxes (Ref Yaw Damper System Engage Trouble Shooting Charts).
(3)
The solenoid valves, transfer valves and position transducers on the hydraulic power pack have proven to be very reliable. Operational problems will more than likely be traced to relays in one of the autopilot accessory boxes. Hydraulic power pack
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problems are usually indicated by operational faults when the yaw damper system is not engaged, such as sloppy centering of the rudder due to hydraulic wear or leaking seals (Ref Chapter 27, Flight Controls). 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737 AMM 飞机维护手册 AUTO FLIGHT 自动飞行 1(32)
