ANTISKID/AUTOBRAKE SYSTEM -AUTOBRAKE FUNCTIONAL DESCRIPTION -RTO ARM LOGIC
EFFECTIVITY BEJ ALL 32-42-00
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ANTISKID/AUTOBRAKE SYSTEM -AUTOBRAKE FUNCTIONAL DESCRIPTION -RTO A/B APPLICATION LOGIC
General
The RTO function applies right hydraulic system pressure to the brakes when these conditions occur:
*
The autobrake selector is in the RTO position
*
Wheel spin-up (average wheel speed of the 4th, 5th, 6th, and 7th fastest wheels is more than 85 knots)
*
After 85 knots, all four thrust lever switches show the levers move from greater than idle to idle
*
No AUTOBRAKE and/or AUTOBRAKE SOL VALVE status message shows
*
No ANTISKID advisory message shows.
When all of the these conditions occur, the autobrake function energizes a relay in the BSCU. This supplies electrical power to the solenoid valve and connects the control valve command signal from the BSCU to the control valve.
The autobrake system sends a full open command to the control valve in the autobrake valve module. This supplies full hydraulic system pressure to the brakes to stop the airplane.
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ANTISKID/AUTOBRAKE SYSTEM -AUTOBRAKE FUNCTIONAL DESCRIPTION -RTO A/B APPLICATION LOGIC
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ANTISKID/AUTOBRAKE SYSTEM -AUTOBRAKE FUNCTIONAL DESCRIPTION -RTO A/B DISABLE LOGIC
Landing Disarm Logic
Full hydraulic system pressure stays applied to the brakes until RTO autobrake is disabled by one of these conditions:
*
You move the autobrake selector to the OFF position
*
Left or right normal metered brake pressure is more than 2400 psi
*
You move one or both thrust levers out of the idle position
*
You move the speed brake lever from the UP position to the DOWN position
*
Either AUTOBRAKE or AUTOBRAKE SOL VALVE status message shows
*
AUTOBRAKE pressure is less than 750 psi for one second during brake application.
The AUTOBRAKE advisory message shows when the system is disabled after an RTO brake application or if RTO application requirements were met and no brake pressure is applied.
To cancel the advisory message, you must move the selector to the OFF position.
During a normal takeoff, the autobrake selector remains in the RTO position until the airplane is in the air. The arming solenoid then releases the autobrake selector and it moves to the OFF position.
EFFECTIVITY BEJ ALL 32-42-00
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ANTISKID/AUTOBRAKE SYSTEM -AUTOBRAKE FUNCTIONAL DESCRIPTION -RTO A/B DISABLE LOGIC
EFFECTIVITY BEJ ALL 32-42-00
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D633W101-BEJ Jan 05/2002
ANTISKID/AUTOBRAKE SYSTEM -INDICATIONS
General
The primary and secondary bite cards in the BSCU send antiskid and autobrake fault data to AIMS for flight deck display.
There is one ANTISKID advisory message. It shows when there is a fault that causes loss of skid protection.
There is one AUTOBRAKE advisory message. It shows when the autobrake system is disarmed, inoperative, or RTO starts but the brakes do not apply. It also shows when the autobrake switch is OFF and the pressure in the autobrake valve module is not shutoff.
Autobrake memo messages show autobrake selector position.
Landing Gear Synoptic Display
The antiskid system shows fault and disabled data for each wheel on the landing gear synoptic display.
ASKID shows next to the applicable wheel when an antiskid fault is active and the ANTISKID advisory or status message shows. If the BSCU loses communication with the flight deck, the AIMS shows ASKID next to each wheel.
When you disable fault indications for a brake, BRAKE shows next to the applicable brake. This makes the ANTISKID advisory message go out of view. You can only disable one brake for each truck.
Landing Gear Brks/Strg Maintenance Page
When a fault and a CMC maintenance message for a wheel are active, one of these labels, shown in decreasing importance, will show next to the applicable wheel:
*
BRAKE DEACT -brake deactivated
*
ASKID PWR -power to the wheel failed
*
ASKID CARD -BSCU card failed
*
ASKID VALVE -normal valve and/or wiring failed
*
ASKID XDCR -transducer and/or wiring failed
*
ASKID ALTN -alternate valve and/or wiring failed.
Only the most important label shows for a wheel when more than one fault is active.
If the BSCU loses communication with the flight deck, the AIMS shows ASKID CARD next to each wheel.
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