AUTO SPEEDBRAKE CONTROL -AUTO SPEEDBRAKE ACTUATOR
EFFECTIVITY BEJ ALL 27-62-00
Page 11
D633W101-BEJ Jan 05/2002
AUTO SPEEDBRAKE CONTROL -RTO SPEEDBRAKE MECHANISM
Purpose
When the pilot commands reverse thrust, the RTO speedbrake mechanism lifts the speedbrake lever out of the DOWN detent and actuates the auto speedbrake thrust reverse switch. The PFC uses the auto speedbrake thrust reverse switch signal to command the auto speedbrake actuator to move the speedbrake lever to the UP position.
Physical Description
The RTO speedbrake mechanism consists of a pair of cam followers, each actuated by a thrust lever cam. Either cam follower turns the speedbrake lever lifter drive segment. The lifter drive segment connects with the speedbrake lever lifter assembly. A return spring returns the lifter to the down position when the thrust reverser lever moves to the idle position.
A switch adjust screw at the rear of the lifter assembly operates the auto speedbrake thrust reverse switch.
Location
The RTO speedbrake mechanism is on the left frame of the thrust lever assembly in the control stand. Remove the left access panel of the control stand to access the RTO speedbrake mechanism.
Functional Description
When the pilot moves either or both thrust reverser levers, one or both thrust lever cams cause the cam followers to turn. This also turns the speedbrake lever lifter drive segment and causes the speedbrake lever lifter assembly to move. As the speedbrake lever lifter assembly turns, it lifts the speedbrake lever out of the DOWN detent. The switch adjust screw at the rear of the lifter assembly then contacts and actuates the auto speedbrake thrust reverse switch.
Training Information Point
The switch adjust screw at the back of the speedbrake lever lifter assembly is adjustable.
EFFECTIVITY BEJ ALL 27-62-00
Page 12
D633W101-BEJ Sep 05/2002
AUTO SPEEDBRAKE CONTROL -RTO SPEEDBRAKE MECHANISM
EFFECTIVITY BEJ ALL 27-62-00
Page 13
D633W101-BEJ Jan 05/2002
AUTO SPEEDBRAKE CONTROL -FUNCTIONAL DESCRIPTION
General
The PFCs control the extension and retraction of the auto speedbrake actuator. The auto speedbrake operates only when the PFCs are in normal mode. The PFCs send extend command signals to the L1 and R ACEs. These ACEs control two auto speedbrake relays.
The L1 ACE energizes the auto speedbrake control relay and the R ACE energizes the auto speedbrake arm relay. Both relays need to be energized to command the auto speedbrake actuator to extend. Both relays need to be de-energized to command the auto speedbrake actuator to retract.
If one relay is energized while the other is de-energized, the auto speedbrake actuator stops.
Auto Speedbrake Actuator
Two sets of limit switches control electrical power to the motor. The actuator position controls the limit switches. As the actuator starts to extend, the fully retracted switch operates. The fully extended switch operates only when the actuator has fully extended. The reverse happens during retraction.
The fully retracted switch has contacts that supply the L1 ACE and PFCs with the actuator status.
Auto Speedbrake Operation During Landing
During landing, the auto speedbrake operates when all these conditions occur:
*
The main landing gear is on the ground
*
The speedbrake lever is in the ARMED position
*
Both left and right thrust resolver angles are not at the takeoff position
*
Both thrust resolver angle signals are valid.
Before landing, the pilots arm the speedbrake lever. During the flare, the pilots move both thrust levers to idle. At touch down, the auto speedbrake actuator fully extends the speedbrake lever. This commands all spoilers to fully deploy.
The auto speedbrake retracts to the DOWN position if any of the above conditions changes after the auto speedbrake has fully extended.
The auto speedbrake retracts to the ARMED position if any of the above conditions changes when the auto speedbrake has partially extended.
Auto Speedbrake Operation During RTO
The auto speedbrake operates during RTO when all these conditions occur:
*
Main landing gear is on the ground
*
Auto speedbrake thrust reverser switch is closed
EFFECTIVITY BEJ ALL 27-62-00
Page 14
D633W101-BEJ Sep 05/2002
AUTO SPEEDBRAKE CONTROL -FUNCTIONAL DESCRIPTION
*
Auto speedbrake thrust reverser switch signal is valid
*
No disagreement fault between the auto speedbrake thrust reverser switch and the thrust resolver angle signal.
