When fog is used, the fog is deflected to the brake
If blowout screens, such as the one shown in figure
14-20, are available, they should be placed around both
side of the wheel for a period of 5 to 10 seconds. Each
main wheels. These screens help to eliminate the
application should be separated by a waiting period of
possibility of damage or injury in the event of a
at least 20 seconds. This method is applied as long as it
blowout. Sudden cooling may cause an overheated
is necessary to control the temperature of the affected
wheel to fracture or fly apart, which could hurl bolts or
fragments through the air with sufficient speed to
assembly.
injure personnel. Required personnel should approach
Once the brake has been properly cooled, permit
overheated wheels with extreme caution in the fore or
the wheel to cool in ambient air. A crosswind or forced
aft directions--never in line with the axle.
air from a blower or fan will assist in cooling the wheel.
NOTE: The area on both sides of the tire and
The aircraft should not be moved for at least 15
wheel, in line with the axle, is where the fragments
would be hurled if the tire were to explode; therefore, it
minutes after cooling operations.
is called the danger area. See figure 14-20.
Q14-16. What type of brake system uses utility or main
Heat transfer to the wheel will continue for some
hydraulic system pressure from the aircraft,
period of time until the brake is cooled. The danger of
which allows for higher brake line pressure?
explosive failure may exist after the aircraft is secured
Q14-17. What is used to check the reservoir fluid level
if action is not taken to cool the overheated brake.
on an independent brake system?
The recommended procedure for cooling
Q14-18. What power source should be removed from
overheated wheel, brake, and tire assemblies is to park
the aircraft prior to operationally checking
the aircraft in an isolated location. Allow the assembly
the emergency braking system?
to cool in ambient air for a period of 45 to 60 minutes.
The use of cooling agents to accelerate cooling is not
Q14-19. During the operational check of the braking
recommended unless operational necessity dictates
system, the antiskid light will illuminate when
their use. The application of the agents exposes
the antiskid switch is placed in what position?
personnel to danger by requiring their presence near the
overheated assembly. However, if it is necessary to
Q14-20. When checking brake linings, what is the wear
accelerate cooling, use an intermittent stream of water
limitation that requires the entire set of linings
or fog.
to be replaced?
When using water, direct a stream to the brake.
Q14-21. How many minutes must the emergency brake
The water should be applied in 10- to 15-second
system be purged with heated nitrogen?
periodic bursts, not in a continuous discharge. Each
Q14-22. When you bleed aircraft brake systems, what
application should be separated by a waiting period of
factor generally determines the method to be
at least 30 to 60 seconds. A minimum of three to five
used?
applications is usually necessary.
Figure 14-20.--Use of blowout screen on overheated brakes.
14-18
