WHEELS-BRAKES-GEAR Flashcards
When is main gear steering activated?
Main gear aft truck is steerable automatically. Operates when the nose wheel steering angle is over 13 deg to reduce tire scrubbing
Max speed for gear extension and retraction?
270 kts or M 0,82
How many tires does the B777 have?
14
Which HYD system is used for normal braking?
The right HYD system
Which HYD systems supplies the steering systems?
Center/RSV for the nose Wheel
Center for the main gear aft axle steering
What HYD system is used for alternate and reserve braking?
Centre HYD system
Is anti-skid available with the Center HYD system?
Yes
In which braking modes is anti-skid available?
Normal
Alternate
Reserve
Accumulator only
Where are the air/ground logic sensors located?
On each main landing gear beam
When is the gear lever lock normally released?
Once airborne
Why is there no OFF selection for the landing gear lever?
Because the system is automatically depressurized
How can the ground landing gear lever lock be manually overridden?
By pushing and holding the landing gear lever LOCK OVERRIDE switch
What is different on the “non normal” format to display gear extension on EICAS?
EICAS displays the locked/transit status of each gear
How does the landing gear extend?
When gear lever is moved DN, the gear doors open, the gears mechanical locks unlocks hydraulically. The gear free-fall without hydraulic power to the locked position and all hydraulically actuated gear doors close. The main gear trucks hydraulically tilts to the flight position.
How is the main gear locked down?
By downlocks hydraulically
How many braces are on each main landing gear?
- A drag brace and a side brace
What type of pump is used for alternate gear extension?
A dedicated DC powered hydraulic pump using Center HYD system fluid
How is alternate gear extension done?
Select down on ALT GEAR switch but first put the gear lever in the down position
How are the gear doors affected by alternate gear extension?
All the hydraullically powered doors remain open
Which HYD system Powers the nose gear steering?
Centre and Reserve system
What is the max steering angle with the tiller?
70 deg
What is the max steering angle with rudder pedals?
7 deg
Will the main gear operate with rudder pedal steering?
No, Operates over 13 deg. Pedals can only give 7 deg
Which hydraulic system gives pressure for reserve braking?
The primary C1 pump
What is indicated by the BRAKE SOURCE light and EICAS message?
Both Right and Center/RSV HYD pressure is low
Which HYD system pressurizes the brake accumulator?
The right HYD system
When is the brake accumulator charged hydraulically?
Continously
Stores pressure if Right HYD system pressure is lost
In which brake modes is anti-skid available?
In all braking modes. (NORM+ALT+ACCUMULATOR ONLY)
In regard to anti-skid, what is the difference between Normal Brake Mode and Alternate Brake Mode?
All main gear wheels are controlled individually in Normal Mode. In Alternate Mode it’s only individual for the aft axle. The fwd and middle works in together as a pair
In which braking modes is autobrake available?
Only in Normal mode
When will autobrake function for a rejected T/O?
Over 85 kts. Both thrust levers must have been retarded to idle to engage. Arming of RTO is only possible on the ground
Will autobrake bring the a/c to a complete stop?
Yes
How is the Park brake set?
Depress both pedals, pull PB lever up, then release pedals
What temp will display BRAKE TEMP message?
When any brake temp is at or above 5,0 (500 deg C)
What 3 situations will cause the TIRE PRESSURE msg on the EICAS?
- Any tire press is above normal range
- Any tire press is below the normal range
- Excessive pressure diff between 2 tires on the same axle
What is pressure range, in PSI, for the Tire Pressure indication on the Gear Synoptic?
0-400 PSI
What is considered “Normal” tyre pressure for the main gear and the nose gear respectively?
Main gear: 220 PSI
Nose gear: 200 PSI
What is the advantage with Carbon brakes over Steel brakes?
- They are lighter weight than steel brakes.
- They can absorb many times more heat during a high speed rejected takeoff.
- Their stopping capability improves as they are warmed up.
What do you do if you get EICAS “BRAKE TEMP” after T/O?
If in the caution zone, extend the gear for at least 8 min. If in the “fuse plug melt zone” extend the gear for minimum 12 min
What is the “taxi brake release system”?
Below 45 kts the anti-skid system releases brakes of one axle pair of each main landing gear. This extends service life and reduces brake sensitivity during taxi. If heavy braking is needed below 45 kts all pairs will be work. Taxi brake release system only works with the Normal brake system(R HYD SYS)
Which hydraulic system has to operational for AUTOBRAKE to work?
The right system
What happens to the brake action applied by the Autobrake system then spoilers and reverse thrust is applied?
Autobrake pressure is reduced as reverse and spoilers are deployed to keep the same deceleration rate.
What does the EICAS message “AUTOBRAKE” mean?
EICAS “AUTOBRAKE” means Autobrake is disarmed or inoperative
What are the requirements for AUTOBRAKE to become active during landing?
AUTOBRAKES 1-4 and MAX works when both thrust levers are at idle and the wheels have spun up.
Speed has to be over 85 kts
Which one of AUTOBRAKE MAX or manual braking give the most brake pressure?
Manual gives more brake pressure than MAX
Can AUTOBRAKE deceleration rate be changed during roll out?
Yes, by rotating the autobrake knob
What does the EICAS message “CONFIG GEAR STEERING” mean?
EICAS “CONFIG GEAR STEERING” means that the main gear aft axles are not centered and locked when T/O thrust is applied.
Describe how the semi-levered gear system works and it’s benefits?
A semi-levered landing gear allows the 777-300ER to lift its nose early during takeoff by shifting the center of rotation from the main axle to aft axle of the three-axle landing gear truck. As the airplane rotates, the nose is allowed to rise higher earlier. A higher nose-up pitch angle can be achived before the tail strikes the ground, which means that Vmu can be achived at a slower speed. It also effectively lengthens the gear strut and provides improved tail clearance as you will hit the ground at a higher pitch angle then otherwise would be the case. The gear feature is independent of the Tail-Strike Protection system, but both give Boeing customers the ability to take off on shorter runways or put more payload on the airplane for the same length of runway.
How many degrees can the aft axel on the main landing gear move durning main gear steering operation?
8 degrees either side
Can you use manual braking to “outbrake”:
- MAX AUTO and
- RTO
Manual braking can “outbrake” MAX AUTO but not RTO as that uses max effort to stop the aircraft
