曝光台 注意防骗
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circuit is satisfied. With N1 mode selected, the A/T controls the throttles
maintaining N1 limit thrust. In SPEED mode the A/T maintains the
airplane's airspeed.
Fig. 35-2 DFCS MCP
[4] Two A/T disengage switches are located on two end of each throttle
lever handle, they provide a means of disengaging the A/T. Two
takeoff/Go-around (TO/GA) switches are located on the aft edge of each
throttle lever, they are provide a means of engaging the A/T in the
takeoff or go-around mode. All four switches are momentary contact type
switches. Each has a set of normally open contacts and a set of normally
closed contacts. The A/T disengage switches are designed to be operated
with the thumb while the hand is on the throttle levers. The two
disengage switches are wired in series and the normally closed contacts
form a part of A/T engage circuits. Pressing either switch will disengage
the A/T. The normally open contacts are in the A/T warning light circuit
and are used to reset the warning light. The TO/GA switches are operated
with a finger tip while the hand is on the throttle lever. Pressing either
switch activates the takeoff or go-around mode for both A/T and AFDS.
Fig. 35-4 A/T modes on EADI
[5] The primary function of the autothrottle interface with the EADI is
for the flight mode annunciator (FMA). The FMA function utilizes the
top of the EADI display to annunciate the autothrottle mode. Engaged
modes are display in green .These modes are N1, GA, RETARD, FMC
SPD, MCP SPD and THR HOLD. ARM annunciation is displayed in
white. In addition, an airspeed tape with a target airspeed index is
displayed on the left side of the EADI.
Fig. 35-3 A/T disengage and TO/GA switches
[6] The takeoff mode is prepared for use by engaging the FMCS in the
takeoff mode with the airplane on the ground. The FMA will annunciate
TO for the N1 limit . Moving the A/T engage switch to the ARM position
arms the A/T for takeoff and FMA will display ARM for the A/T . The
A/T cannot be engaged on the ground unless the FMCS is in the takeoff
mode. Pressing either TO GA switch engages the takeoff mode. The
throttles advance at 15 degrees per second to the predicted throttle
position and the FMA A/T annunciation changes from ARM to N1.
When the engine N1 approaches the takeoff rating the throttles make
final adjustments to overcome system rigging tolerances and obtain the
correct N1. At 84 knots CAS the A/T enters a hold state, two
independent circuits ensure that the throttle servomotor are unable to
move. A THR HOLD annunciation comes into view on both FMA when
both hold circuits have operated. In addition to N1 operation in the
takeoff mode, the A/T will control N1 in climb. Pressing the N1
pushbutton on the MCP engages the N1 mode and the A/T adjusts to the
climb thrust rating, the FMA annunciates N1 and the pushbutton N1
switch on the MCP is illuminated.
[7] As the airplane approaches the selected altitude under VNAV control,
the A/T is switched into the FMC SPD mode. It annunciates FMC SPD
and will remain in that mode during the altitude hold mode. When the
airplane begins to descend under VNAV control, the A/T retards the
thrust levers to idle and annunciates RETARD. The mode is terminated
by either pilot stopping the throttles or the throttles driving against the
idle stop . The A/T then goes to and annunciates ARM mode.
[8] When the DFCS captures the glide slope, the VNAV mode is
disengaged and the A/T switches to the MCP SPD mode. Selection of
desired speed is made on the DFCS MCP. The A/T annunciates MCP
SPD and the SPEED pushbutton on the MCP is illuminated. The
pushbutton is illuminated to indicate to the pilot that pressing it will
cause the A/T to revert to ARM. During the landing flare maneuver, the
flare retard provides a thrust reduction to idle in six seconds. The FMA
will show RETARD. At squat, the throttles are moved aft at eight
degrees per second to insure throttles move quickly to idle if any residual
throttle displacement exists. The A/T disengages two seconds after squat
with no warning light.
READING MATERIAL
* Engine bloom ( N1 bloom ), A change in engine N1 and thrust indicated on the N1 gages and
detected by the autothrottle BITE during throttle hold operation ------- see p.1 1-103 N1 bloom
译作N1 激增.
QUESTIONS TO LESSON 35 READING MATERIAL
1. How is inflight fault recording for the A/T system triggered?
2. Where are the inflight failures recorded in ?
3. What does the history include ?
4. How many flight deck effects (FDE) associated with A/T engage
problems? What are they ?
5. When does the A/T LIM light illuminate ?
6. Where is the illumination of the A/T LIM light stored ?
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