During a refused takeoff (RTO), the auto speedbrake also operates when all these conditions occur:
*
Main landing gear is on the ground

*
Either engine thrust reverser is operated

*
Thrust resolver angle signal that is operated is valid.

During a RTO, when the pilot moves at least one of the thrust reverser levers, the auto speedbrake extends the speedbrake lever. This commands all spoilers to fully deploy. When the thrust reverser levers are returned to the normal position, the speedbrake lever stays in the UP position as long as the logic for autospeedbrake operation during landing is valid.
Main Landing Gear On Ground

One of the conditions for the auto speedbrake actuator to extend is that the main landing gear is on the ground.
The PFCs determine that the main landing gear is on the ground from a combination of signals received through the AIMS.
EFFECTIVITY BEJ ALL
During approach, the main landing gear is extended and the main gear trucks tilted by hydraulic pressure. At touch down, the main landing gear is on the ground when the main gear trucks are not tilted with hydraulic pressure on the truck tilt actuators. The radio altimeter signals verify that the main landing gear is on the ground.
The weight-on-wheel cards supply signals when the airplane is on the ground. These signals verify that the main landing gear is on the ground during RTO.
Indications
The EICAS advisory and status messages AUTO SPEEDBRAKE indicate that the auto speedbrake is defective and does not operate. This happens when one of these conditions is present:
*
Either L1 ACE or R ACE is defective

*
Auto speedbrake actuator does not retract within 2 seconds of command

*
Auto speedbrake actuator stays retracted for 2 seconds after a command to extend

*
Loss of data from one thrust resolver angle with the related engine running

*
Loss of data from both thrust resolver angles

*
Loss of valid data of the truck tilt pressure transducers from both the L and R HYDIM cards

*
Loss of valid truck tilt position data from either PSEU 1 or PSEU 2

*
Center hydraulic system is failed

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Page 15 D633W101-BEJ Sep 05/2002

AUTO SPEEDBRAKE CONTROL -FUNCTIONAL DESCRIPTION

*
Truck tilt pressure is low with the main landing gear down and locked and the center hydraulic system pressure is high

*
Radio altitude data is not valid

*
PFCS is not in normal mode.

Although the operation of the auto speedbrake is available only in normal mode, these conditions cause the message to show in the normal, secondary, and direct modes.
EFFECTIVITY BEJ ALL  27-62-00 
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AUTO SPEEDBRAKE CONTROL -FUNCTIONAL DESCRIPTION

EFFECTIVITY BEJ ALL  27-62-00 
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777 AIRCRAFT MAINTENANCE MANUAL

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Page 1 D633W101-BEJ Jan 05/2002
BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.

LEADING EDGE SLATS -INTRODUCTION

General

The leading edge (LE) slats improve the takeoff and landing performance of the airplane. When the slats extend, they increase the lift of the wing. They also increase the angle of attack (AOA) at which the wing stalls.
The slats are part of the high lift control system (HLCS). The HLCS electrically controls the slats with a fly-by-wire system.
During takeoff and landing, the pilots use the flap lever to command the slats to extend to the sealed or gapped positions. After takeoff, the pilots use the flap lever to command the slats to retract to the up position.
Each wing has an inboard slat, a krueger flap, and six outboard slats.
Slat Operation

The slats operate in sequence with the flaps. At cruise speed and altitude, slat extension is inhibited.
During secondary mode operation, the load relief function retracts the slats at high airspeed.
The autoslat function extends the slats to improve the airplane stall performance near stall conditions.
The slats are monitored for skew or asymmetry. When there is a skew or asymmetry, the slat drive shuts down.
Abbreviations and Acronyms
*
ADP -air driven pump

*
AIMS -airplane information management system

*
altn -alternate

*
AOA -angle of attack

*
ARINC -Aeronautical Radio, Inc.

*
ASCPC -air supply and cabin pressure controller

*
EICAS -engine indication and crew alerting system

*
EXT -extend
　
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