Chapter 6 - Landing Gear Flashcards
Landing Gear Types?
Rubber Bungee
Cantilever Spring
Oleo Pneumatic Strut
Rubber Bungee
- Use Tubular Struts
- Landing forces directed against the turns in the rubber.
Cantilever Spring
- Comprises a tube or strip of tapered spring steel.
- Upper end is attached to the fuselage and the lower end terminates at the axle.
Oleo Pneumatic Strut
- Found on more advanced light aircraft.
- Combination of air and Hydraulic fluid is used to absorb the shock during landing.
- Often just the Nose gear that uses this.
Wheel Bogie?
- Used to fit additional wheels to the landing gear.
- At least 4 wheels per landing leg.
- Mounted to a ‘bogie beam’.
Requires a large amount of space to stow.
Shock Absorbers?
90% of landing shock.
Connected to the wing spars.
- Gas (Nitrogen) inside cylinder acts as spring to absorb loads.
- Hydraulic oil acts to dampener the gas springs during rebound.
Preflight check that should be carried out on the Shock Absorbers?
Fescalized Portion should be checked to see if it has bottomed out:
- Sign of low pressure
- or Fluid leak.
Purpose of:
Oleo Leg
Absorbs loads and dampens recoil
Purpose of:
Wheel Axles
Wheel mounting shaft, allows rotation.
Purpose of:
Bogie
Axles connected by a central bogie beam to support complete wheel assembly.
Purpose of:
Drag Strut
Braces the landing gear against the forward & rear shock loads.
Purpose of:
Upper Sidestay
Braces the landing gear against side motion (Taxing creates the biggest loads of the sides).
Purpose of:
Gear Doors
Provide aerodynamic closure to the landing gear bay.
Purpose of:
Torque Link (Scissor Link)
Prevents rotation of the inner oleo cylinder.
Purpose of:
Free Castoring?
Uses wheel brakes to turn the aircraft
Purpose of:
Automatic Self-centring springs / Centring Cams?
Ensure the wheel is centred when retracting.
Won’t knock on the structure and cause damage.
What is VLE?
Max speed at which landing gear may be extended.
What is meant by VLO?
Max speed at which the landing gear may be “Operated”.
Type of locks used to lock Landing gear?
- Geometric
- Over centre locking.
Requires no hydraulic pressure to lock the gear into position.
Uses gravity.
REQUIRES HYDRAULIC ACTUATOR TO BREAK THE LOCK TO RETRACT.
What is a ‘Up-lock’?
Hook lock which requires hydraulic pressure to engage and release.
What are ‘Ground Locks’?
Manually fitted Ground Locks when aircraft is parked.
- Prevent inadvertent movement of the gear.
- Put in place before towing.
Have a red tag attached.
FORGETTING TO REMOVE THESE WILL LEAD TO FAILURE OF RETRACTION.
Green Gear light means?
Locked.
Red Gear light means?
Unlocked and traveling.
No Gear lights mean?
Locked and up.
Dolls-eye?
System used to indicate gear position.
Magnetic.
Ways to lower gear in emergency?
- Hand Cranked
- Compressed Nitrogen to blow the gear down - Cannot be retracted after gas is dispelled.
- Gravity or free fall system. Releases the up-locks.
What is a Tiller used for?
Manoeuvring on the ground at low speeds.
75degrees of rotation.
Operated by a small electric or hydraulic motor.
What can cause ‘Shimmy’?
- Worn or broken torque links.
- Wear in the wheel bearings.
- Low or uneven tyre pressure.
Shimmy Prevention?
- Hydraulically locking steering pistons.
- Hydraulic Dampeners.
- Self Centring Springs.
- Double Nose Wheels.
- Nose wheel tyres with 2 contact points known as ‘Marstrand Tyres’.
Redundancy procedure for landing gear lights?
2 light bulbs.
