11.13 Landing gear Flashcards
What are the advantages of a nose tricycle gear system over a tail system?
- Directional stability
- Higher landing speeds (better braking ability)
- Greater decrease in lift after touchdown (less AOA on wings)
- Better visibility during takeoff and landing
What type of undercarriage will give a larger footprint?
Multiple bogies
What part of the undercarriage supports the aircraft weight?
The shock strut
What function does the gas fulfil in a shock absorber?
It acts as the spring to absorb the shock
What characteristics will a shock absorber display if it is overfilled with oil?
It has harsh operation (insufficient spring)
What two internal components of a shock absorber provide damping during extension?
- Laminar flow orifice
- Tapered metering pin
What component will transfer vertical load to the airframe without impacting torque?
Spherical bearing
What is the purpose of angling the nose gear leg forward of vertical?
Nose wheels castor to centre
How is landing gear prevented from lowering in high speed?
A mechanical lock or speed signal which causes a safety valve to isolate the hydraulics
When will the autobrake system disengage?
When the pilot uses the brakes
What is the principle of operation if a wheel speed transducer?
It converts the rotational speed of the wheel into an electrical signal
What component will close if the brake line pressure differential gets too high?
The hydraulic fuses
What effect will thrust reverse have on the auto braking system?
The auto brake will reduce brake pressure to keep the pre-selected deceleration rate
When would a flat spotted tyre require changing?
When there is shimmy on braking or it’s worn to limits
What is the purpose of the drive keys on a wheel?
So the wheel can drive the brake discs
The landing gear shortening mechanism will do what?
Shorten the main gear for retraction into the wheel well
What is the cockpit indication that all landing gear is stowed and locked?
No lights
How is nose wheel steering achieved on a large commercial aircraft?
- By the use of a steering tiller that sends electrical signals to a hydraulic steering control valve
- By the use of a steering tiller to mechanical linkages to a hydraulic steering valve
How can undercarriage retraction tests be carried out on 1 leg only?
By leaving downlock pins in position
Which part of an undercarriage leg ensures it remains down and locked?
Down lock mechanism (geometric lock and actuator)
Which part of an undercarriage leg absorbs the load on landing?
The shock strut
What are the component parts of a heat stack in the braking system?
Rotors and stators
On a power braking system, what component ensures demand is met at the unit?
The brake metering valve
The support strut of the undercarriage carries what load?
The weight
How is damage to the steering mechanism prevented when towing?
Bypass valve
How is the undercarriage leg held in the up position?
By the use of an up lock
In which direction do the plies of a conventional tire run?
Cord plies run diagonally
Why is there a minimum turning radius applied to aircraft during towing or taxiing?
To prevent damage to the undercarriage and tires
What is the purpose of the torque link on an undercarriage leg?
They permit the inner cylinder to move up and down in the outer cylinder but prevent it turning
Apart from the lock pins, what else prevents the undercarriage from retracting on the ground?
The landing gear selector cannot be selected up without overriding the lever lock
What would occur if the anti-skid system detects a locking wheel?
A full release signal is sent to the brakes by the locked wheel sensor allowing the wheel to rotate. The skid detection system can then regulate the braking again
What is the position of the main undercarriage doors once the main undercarriage has been extended?
Normally closed
Why should a wheel be deflated before removing from the axle?
To prevent high pressure splitting of the wheel
What would occur if a wheel assembly was subject to an overheat situation?
Fusible plugs would melt
In which direction should a wheel be approached for servicing?
In front or behind
