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(m)
The servo failure monitor controls the TAT failure flag and the plus-minus display. The failure monitor circuit provides a ground to one end of the control solenoid for either a plus or minus display. The TAT failure monitor circuits also monitors for a power failure by removing ground from both leads of the control solenoid, causing the plus-minus indicator to display a failure flag.
(n)
With a TAT probe short or open, an abnormally high positive or negative output signal from the TAT sense module is applied to the function generator. The excessively high input, if negative, is applied to the level detector; if positive, it is inverted and applied to the level detector. The level detector changes from a normal negative output stage and produces a positive output to the failure monitor. This causes the failure monitor to remove the ground from the control solenoid and a failure flag is displayed.
(o)
During test conditions, when the TEST switch is pressed and the auto throttle is not engaged, a ground and 28 volts dc is provided in the test lines from the computer. The dc voltage energizes the test relay in the indicator and establishes fixed operating voltages for the TAT servo loop. This fixed operating voltage causes the TAT motor to drive and display approximately +10.C. The EPRL computation circuits are also adjusted so the combination of mode and test signals produce specific test displays on the EPRL readout.
B. Modes of Operation
(1)
Takeoff Dry (TOD)
(a) This is the maximum thrust available without the use of water injection. The rating is selected by setting the aircraft throttle to obtain the computed TOD thrust in terms of engine pressure ratio for the existing ambient temperature and barometric pressure. The rating is time limited and is used only for takeoff and as required for reverse thrust operations during landing.
(2)
Takeoff Wet (TOW) (AT 701-799)
(a) This is the maximum thrust available for takeoff. The rating is selected by actuating the water injection system and setting the aircraft throttle to obtain the computed TOW thrust in terms of engine pressure ratio. The rating is time limited, restricted to takeoff, and has altitude and ambient air or water temperature limitations.
(3)
Go-Around (GA)
(a) The GA or inflight takeoff is similar to TOD. This rating is the power setting for a missed approach.
(4)
Maximum Continuous (CON)
(a) This rating is the maximum thrust that may be used continuously and is intended only for emergency use. The rating is selected by adjusting the throttle to obtain a predetermined engine EPR limit.
(5)
Maximum Climb (CLB)
EFFECTIVITY
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(a) This rating is the maximum thrust approved for normal climb. The rating is selected by adjusting the throttle to obtain a predetermined engine EPR limit.
(6) Maximum Cruise (CRZ)
(a) This rating is the maximum thrust approved for cruising. It is obtained in the same manner as maximum climb and maximum continuous thrust.
C. Controls
(1) Power is applied to the TAT/EPRL system when circuit breakers TAT/EPRL - COMP AND IND on panel P7 are closed. The system is shut down when the circuit breakers are opened.
EFFECTIVITY
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TOTAL AIR TEMPERATURE/N1 LIMIT INDICATING SYSTEM - TROUBLE SHOOTING
___________________________________________________________________
1. General
_______
A. The following trouble shooting procedures are based on performance of the system operational test and are presented in tree-type format. The test steps (heavy-line box) are connected by shaded arrows to show the OK condition path. When all steps in the OK condition path check out, system is operable.
B. When a test step does not check out, follow the NOT OK line to the box containing the trouble symptom. Turn to the procedure indicated and continue to follow a single line by analyzing the results of each test step until the required corrective action is determined. Perform the specified corrective action, then repeat the step at which the failure was encountered.
CAUTION: DO NOT USE LOW IMPEDANCE TEST EQUIPMENT FOR TROUBLE SHOOTING
_______
AS DAMAGE TO SYSTEM COMPONENTS WILL RESULT.
2. Prepare for Trouble Shooting
____________________________
A. Provide electrical power. (Refer to 24-22-00, Manual Control -Maintenance Practices.) Apply power.
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