09 Landing GearTyres Brakes

The principal reason why light training aircraft have fixed undercarriages is that:

• Training aircraft need to manoeuvre on the ground.

• Training aircraft need to ensure that kinetic energy on landing is absorbed.

• Training aircraft need to be supported at a convenient height.

• The reduced performance caused by the additional drag of a fixed undercarriage is offset by its simplicity, low cost and easy maintenance.

The 'Ply Rating' of a tyre:

• Indicates the number of rayon or nylon cords.

• Shows how many breaker strips are embedded in the tyre.

• Has nothing to do with the strength of the tyre.

• Is an index of the strength of the tyre.

Most nose wheels on modern light aircraft are:

• Oleo pneumatic shock-absorber struts.

• Spring steel struts.

• Spring coil struts.

• Compressed rubber struts.

Tyre creep may be identified by:

• Two yellow diametrically opposed arrows painted on the tyre sidewalls.

• A tyre pressure check.

• Alignment marks painted on the tyre sidewall and wheel flange.

• Two white blocks painted on the wheel flange.

Awl vents in an aircraft tyre:

• Prevent damage to the tyre which might be caused at high altitude because of pressure trapped between the tyre plies.

• Enable tyre creep to be detected.

• Assist in balancing the wheel assembly.

• Prevent tyre slippage.

On a light aircraft fitted with a mechanically steered nose wheel, steering on the ground is normally effected by:

• Cables operated from the aileron control wheel.

• Use of the differential braking technique, only.

• Hydraulic jacks which allow self-centring.

• Control rods/cables operated by the rudder pedals.

Aquaplaning speed:

• Increases as the depth of tread on the tyres reduces.

• Increases as the depth of water on the ground increases.

• Can be calculated, in knots, by multiplying the square root of the tyre pressure in PSI by nine.

• Is measured in miles per hour.

If a fire occurs in a wheel and tyre assembly and immediate action is required to extinguish it, the safest extinguishant to use is:

• Dry powder.

• Carbon dioxide (CO2).

• Bromotrifluoromethane (BTF).

• Water acid.

Tyre creep:

• Can be prevented by painting lines on the tyre and wheel.

• Refers to the movement of an aircraft against the brakes.

• Can be recognised by the misalignment of markings painted on the tyre and the wheel.

• Can be prevented with glue.