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Engine Synchronizer System
The engine synchronizer system automatically matches the N1 or N2 speed or EPR of left engine to match right engine. The system includes a three position (N1, OFF, N2) ENG SYNC selector, ENG SYNC ON annunciation, and control system with actuator to trim left engine fuel control. The pilot can override the system at any time with throttles.
When the ENG SYNC selector is placed in N1 or N2, signals from the tachometer generators causes engine synchronizer system to trim left engine fuel control until left engine RPM (N1 or N2) matches right engine.
On airplanes with the –904 DFGC, the DFGC provides signals to match EPR of left engine to right engine when ENG SYNC selector is in OFF and autothrottle system is engaged in EPR LIM mode.
On airplanes with a -906 or -930 DFGC, the DFGC provides signals to match EPR of left engine to right engine when ENG SYNC selector is in OFF, autothrottle system is engaged, both EPRs are valid, and one EPR is greater than 1.1 EPR.
The engine synchronizer actuator is centered in its range of motion when both ENG SYNC selector and autothrottles are OFF. An ENG SYNC ON annunciation on the overhead panel will come on when landing gear handle is in the down position and the ENG SYNC selector is in N1 or N2 position.
Thrust Recoveries for Engine Failure During Takeoff
In takeoff mode, two separate systems attempt to provide maximum available thrust when the performance of one engine significantly differs from the other. These systems are automatic reserve thrust (ART) and automatic thrust restoration (ATR).
Automatic Reserve Thrust (ART) System
The ART system combines features of the digital flight guidance computer (DFGC) and the JT8D-200 fuel control to provide maximum rated thrust in the event of an engine failure during a normal thrust takeoff. Upon actuation of the ART system, thrust is increased without throttle movement by the opening of a solenoid-operated fuel valve in the engine fuel controls of both engines.
The ART system is READY when the airplane is on the ground, the ART switch is in AUTO, either slat is extended, both engines are operating at or near idle, and the ART system self-test is complete. The ART system is subsequently armed when the N1 on both engines reaches 64% RPM.
The ART system is actuated when the DFGC detects any one of the following: 30.2% differential in N1 RPM, invalid N1, DFGC failure, electrical power loss, or manual DFGC switching. Upon actuation, the ART system increases the EPR of the operating engine(s) from normal takeoff EPR to maximum takeoff EPR (an increase of approximately .05 EPR) by opening the solenoid-operated fuel valve in the engine fuel control. Once ART is actuated, the maximum takeoff EPR limit is displayed on the thrust rating indicator, and the EPR gauge. Once actuated, the ART system is latched (ART fuel valve remains open) until the ART switch is moved to OFF.
The ART has an automatic self-test feature. If the ART system fails the self-test, the ART INOP annunciation illuminates. Dispatch is allowed with a failed self-test; however, the ART switch must be moved to OFF to disable the ART system.
The ART switch, with AUTO and OFF positions, is on the upper instrument panel. Two annunciator lights are on the center instrument panel. The READY light indicates ART has successfully passed the self-test. The ART light indicates the system has successfully activated.
Automatic Thrust Restoration (ATR) System
The Digital Flight Guidance Computer (DFGC) automatic thrust restoration (ATR) is a feature, separate from the ART system, that increases thrust under certain conditions in the event of an engine failure during takeoff. Once activated, the ATR will unclamp the throttles (if the autothrottle system is engaged) and move both of them equally until one of the engines reaches the Go-Around EPR Limit.
The ATR is armed if:
.
The flight director pitch axis is in takeoff mode,
.
The airplane is above 350 feet radio altitude, and
.
Both engine EPRs are below the Go-Around EPR limit.
After arming, the system will activate if the differences between the engines are greater than or equal to 0.25 EPR and 7% N1 (in the same direction), or (for DFGC models -930) the airplane’s vertical speed decreases to less than zero for 5 seconds. In these cases, the throttles will unclamp (if the autothrottle system is engaged) and move to the Go-Around EPR limit.
If ART is armed and the ATR is activated, the EPR limit will be the maximum inflight takeoff rating reduced by the same amount that the ART is designed to provide. This correction prevents overboosting the engine if the ART system subsequently actuates.
Continental
Rev. 12/01/00 #29 Flight Manual
Thrust Settings for Takeoff
These are the four settings available for takeoff thrust in ascending order:
Reduced Thrust (FLEX T.O.)
This is the preferred thrust setting for takeoff, as its use will greatly extend engine service life. An assumed temperature is dialed into the ASSUMED TEMP selector, the ART switch is selected to OFF, and TO FLX is selected on the TRI. The autothrottles are used if operational.
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本文链接地址：MD-80 Flight Manual 麦道80飞行手册 2(190)
