49 Questions
What is the most common cause of spongy brakes?
Air in the system
What type of damage can over-inflated tires cause?
Wheel flange damage
What is the primary function of a brake debooster valve?
To apply brake pressure slowly and release the brakes quickly
How should tubeless tires be stored?
Vertically
On a wheel bogie unit, what is considered positive camber?
When the bottom of the wheels are closer together
What is the typical cause of a brake fluid leak?
Damaged brake hoses or fittings
What is the purpose of fuse plugs in aircraft tires?
For overpressure protection
What is the purpose of a breaker strip in an aircraft tire?
To provide strength
If fluid leaks along with air while oleo charging, what is the likely cause?
Caused by a leaky seal
What does a red dot or triangle mark on an aircraft tire indicate?
The light part of the tire
What is the cause when the main landing gear extends, then begins to retract again after selection?
A faulty selector valve
When fitting a tire, where should the red dot be positioned?
Adjacent to the charging valve
Compared to normal brake units, composite brake units have which of the following characteristics?
Have less weight and increased efficiency at high temperatures
What is the purpose of a restrictor valve in an undercarriage system?
To reduce the speed of undercarriage extension
What could be the fault if an undercarriage tends to creep back up after being lowered?
A leaky selector valve
Where are vent holes found on aircraft tires?
Both tubed and tubeless tires
Which of these is the correct method of nose wheel steering in a modern aircraft?
A separate pilot operated control
What is the purpose of the fusible plugs installed in some aircraft wheels?
To melt at a specified elevated temperature
What does excessive wear in the shoulder area of an aircraft tire indicate?
Under-inflation
To what level can ribbed tires with marker tie bars be worn?
To the top of the tie bar
Why are bogie type undercarriages used on large aircraft?
To spread the weight over a large area
What is used to position the bogie beam at a suitable angle for retraction and landing on large aircraft?
Hop damper
What type of gas mixture is used to inflate the braked wheel assemblies on large aircraft?
Nitrogen and not more than 5% of air
What is the purpose of brake deboosters?
To reduce the hydraulic pressure entering the brakes
Where is a modulator fitted in an aircraft braking system?
Anti-skid units
In the case of pressurized aircraft, what is the status of the nose-wheel bay?
Not pressurized
What is the purpose of the flutter plate in a shock absorber?
Permit free flow of oil during compression and restriction of oil during extension
How should made-up wheels be stored?
Vertical at 20/30 PSI charge
What does a green/grey dot marking on an aircraft tire casing represent?
Breather points
What is the function of the oil in a shock absorber?
Damp the rebound
How much oxygen is allowed in a tyre as a maximum?
5% by volume
What does the number 32 represent in a tire specification like '32 x 10.75-14'?
Outer diameter
What would cause fluid to come out of the air valve when an oleo leg is depressurized?
The leg is serviceable - the separator has bottomed
What is the correct procedure when ice is noticed in the valve stem while inflating a tire?
Wait for the ice to melt before proceeding with inflation
What is the purpose of water dispersing treads on aircraft tires?
To prevent hydroplaning and maintain grip on wet runways
When installing a new tire on a wheel hub, where should the red spot on the tire be aligned?
In line with the valve assembly
What is the purpose of torque links on a single oleo leg with a stub axle landing gear?
To keep the wheel in track and prevent excessive side loads
What does a red or yellow line on an inner tube indicate?
A heavy spot where additional weight is needed for balancing
How is brake wear checked on a multi-brake unit with automatic adjusters?
By applying the brakes and checking the protrusion of the indicator pins
What is the primary function of an anti-skid device in an aircraft?
To prevent the wheels from locking during braking
Why is a hydraulic damper fitted to a nose wheel steering system?
To reduce vibration and shimmy
What factor determines the type of oil used in an undercarriage leg?
The types of seals the leg uses
In an anti-skid system, what action is taken to achieve efficient braking?
Brakes are modulated to prevent locking
If an undercarriage oleo has insufficient deflection, what is the likely cause?
Air pressure too high
What is the function of a Maxaret in an aircraft system?
Skid control
Why does the pilot receive an audible warning during descent for landing?
The landing gear is not locked down
Where is the restrictor positioned in the landing gear hydraulic retraction and lowering system?
In the landing gear up line
What is the purpose of using wheel speed information in an auto speed brake system?
To ensure the aircraft has touched down and allow a time lapse before spoiler deployment
What is the purpose of a fusible plug fitted to an aircraft wheel?
To prevent tire bursts due to high temperatures from excessive braking
Study Notes
Braking Systems
- Spongy brakes are usually a result of air in the system.
- A brake debooster valve is provided for applying brake pressure slowly and releasing the brakes quickly.
- Anti-skid devices can reduce aquaplaning.
- In an anti-skid system, brakes are modulated to give the most efficient braking.
Undercarriage Systems
- Over inflated tyres may cause damage to the wheel flange.
- Tubeless tyres are stored vertically.
- On a wheel bogie unit, positive camber is when the bottom of the wheels are closer together.
- A restrictor valve can be used to reduce the speed of the undercarriage extension.
- A fusible plug fitted to an aircraft wheel prevents tyre bursts due to high temperatures created by excessive braking.
Tyres
- A breaker strip in an aircraft tyre is to provide strength.
- A red dot/triangle mark on aircraft tyres means the light part of the tyre.
- Fuse plugs in aircraft tyres are for overpressure protection.
- Vents holes are found on both tubed and tubeless tyres.
- Tyre creep could be caused by under pressure.
- Excessive wear in the shoulder area of an aircraft tyre is an indication of under-inflation.
Landing Gear
- On large aircraft, bogie type undercarriages are used to spread the weight over a large area.
- A hop damper is used to position the bogie beam at a suitable angle for retraction and landing.
- The minimum aquaplaning ground speed is 8.6 times the root square of the tyre pressure in psi.
Miscellaneous
- Brake pads should be replaced if they are worn out due to a badly corroded and pitted brake disk.
- The type of fluid in an oleo strut will depend upon the heat generated in operation of the system.
- A restrictor valve may be used to slow down undercarriage extension.
- The function of the oil in a shock absorber is to damp the rebound.
- The purpose of the flutter plate in a shock absorber is to permit free flow of oil during compression and restriction of oil during extension.
- Made up wheels should be stored vertically at 20/30 PSI charge.
- When checking for alignment of a MLG, check symmetry, tracking, and camber.
- A green/grey dot marking on aircraft tyre casing represents breather points.
- When inflating a tyre and you notice ice in the valve stem, wait for the ice to melt before carrying on with inflation.
Test your knowledge on aircraft maintenance with questions related to spongy brakes, over inflated tires, and brake deboost. Find out the correct answers with explanations from Jeppesen A&P Technician Airframe Textbook.
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