Explanations: Aircraft Landing Gear Systems

Question 1

Why would the brakes drag if the piston return spring broke?

Answer 1

Because the brakes would not release properly.

Question 2

Why would the brakes be spongy if there was air in the system?

Answer 2

Because hydraulic fluid is noncompressible, whereas any air in the system will compress.

Question 3

If the tire is still inflated, what will happen to the two wheel halves as the tire is taken apart?

Answer 3

They will spread apart dangerously.

Question 4

How is the disk in a cleveland single-disc brake attached?

Answer 4

It is rigidly attached to the wheel and rotates between linings that are riveted to the backplate and the pressure plate in the caliper. The caliper is free to float laterally on two anchor bolts that ride in holes in the torque plate.

When the brakes are applied, the caliper moves out on the anchor bolts to provide equal pressure on both sides of the rotating disk.

Question 5

What do expander-tube type brake types depend upon for operation?

Answer 5

The depend upon fluid inside the tube for their application.

Question 6

What is a brake debooster valve?

Answer 6

a component in brake systems that are installed between the power brake control valve and the wheel cylinders of aircrafts that are equipped with power brakes that use pressure supplied by the aircraft main hydraulic system.

System pressure is too high for smooth brake application, so the debooster decreases the pressure by increasing the volume and increases the flow of fluid to the brakes so they will apply smoothly and release quickly.

Question 7

Why might a brake system have a power brake control valve?

Answer 7

In a high pressure system, when the volume and pressure of hydraulic fluid required cannot be produced by a master cylinder, a power brake control valve (or a brake metering valve) recieves the brake pedal input either directly or through linkages.

The valve meters hydraulic fluid to the corresponding brake assembly in direct relation to the pressure applied to the pedal.
It is the key element in a power brake system.

Question 8

What happens when the brake pedal is released?

Answer 8

pressure is removed from the inlet port. Then, the piston return spring moves the piston rapidly back to the top of the debooster. The rapid movement of the piston causes a suction in the line to the brake assembly that results in a fast release of the brakes.

Question 9

What is an air valve core stem?

Answer 9

It’s thing like where you put air into a bike tire.

Question 10

What will happen if there is a heavy spot on a tire?

Answer 10

It will hit the ground first and get the most wear.

Question 11

When are power boost brake systems used?

Answer 11

on aircrafts that are too heavy or land too fast to employ independent brake systems, but are too light in weight to require a power brake system.

Question 12

What is the caliper in a brake system?

Answer 12

The housing for the brake linings.

Question 13

What is a steering damper?

Answer 13

a hydraulically operated device that accomplishes the functions of steering and eliminating shimmying.

The steering damper automatically reverts to damping when, for any reason, the flow of high-pressure fluid is removed from its inlet.

Question 14

14 CFR 43, appendix A

Answer 14

MAINTENANCE, PREVENTATIVE MAINTENANCE, REBUILDING, AND ALTERATION

the removal, installation, and repair of landing gear tires by a private pilot, on an aircraft that is owned and operated by him or her, is considered to be preventative maintenance.

Question 15

What state are the… shit i don’t know. just read the answer.

Answer 15

With the port open when the brakes are released, there is an open passage between the master cylinder and the reservoir. But if the compensator port is clogged, some fluid can be trapped in the brake line, keeping the brake partially applied.

Question 16

Why should you not set the parking brake when the brakes are hot on an aircraft equipped with hydraulically operated multiple-disk type brake assemblies?

Answer 16

Because it will cause the brake disks to warp.

Question 17

What is a shuttle valve?

Answer 17

A valve that has two inlet ports and one outlet port, and a free floating ball in the center of the valve. When fluid flows through one inlet port, it pushes the ball to block the opposite inlet port, and vice versa. Through this mechanism, two different systems are isolated from each other.

Question 18

How do you service an oleo strut?

Answer 18

Bleed all of the air out to collapse the strut, and remove the strut filler valve. Completely fill the collapsed strut with 5606 fluid, and exercise the strut by moving the piston into and out of the cylinder to work all of the air out of the strut. Replace the filler valve and, with the weight of the aircraft on the wheel, fill the strut with compressed air or nitrogen until the strut extends to the correct height.

Question 19

What is the compensating port?

Answer 19

A compensating port in a brake master cylinder is a passageway open between the reservoir and the master cylinder when the brake is completely released.

Fluid can flow from the reservoir into the master cylinder back into the reservoir as it expands or contracts due to temperature changes.

Question 20

What is a centering cam?

Answer 20

Many retractable landing gears use a centering cam to center the nosewheel when all the weight is off of the shock strut. The centering cam ensures that the wheel is positioned so it will fit into the wheel well properly when it is retracted.

Question 21

What is meant by the proper operating position of the strut?

Answer 21

the proper amount of air in the strut.

Question 22

What is a brake actuating cylinder?

Question 23

How is a lockout debooster different from a ordinary debooster?

Answer 23

It also serves as a hydraulic fuse. It will lock out the system after a given amount of fluid passes through it.

In an ordinary debooster, when fluid is lost, the piston moves to the bottom of its stroke and the riser unseats the ball check valve, and fluid from the power control valve passes through the piston shaft to replace the lost fluid.

In a lockout debooster, when fluid is lost, the piston moves to the bottom of its stroke and the riser unseats the ball check valve, but the spring-loaded lockout valve prevents fluid from entering the lower chamber until the reset handle is lifted.

Question 24

What are fusible plugs?

Answer 24

they are threaded plugs that have a core that melts at a lower temperature than the outer part of the plug. This is to release air from the tire should the temperature rise to a dangerous level. A close inspection should reveal whether any core has experienced deformation that might be due to high temperature. If detected, all thermal plugs in the wheel should be replaced with new plugs.

Question 25

What purpose do fusible plugs serve?

Answer 25

They melt at a specified temperature, relieving the air pressure and deflating the tire, rather than allowing the tire to explode.

Question 26

Why would the electric motor used to raise and lower a landing gear most likely be a split field series-wound?

Answer 26

Because of its high starting torque and a split-field to both raise and lower the gear.

Question 27

Why does a chevron seal face the direction of fluid pressure?

Answer 27

So that the hydraulic pressure will force the seal tightly against the cylinder walls.

Question 28

What is a pressure regulator?

Answer 28

When the system pressure is high enough, the pressure regulator traps the fluid in the system, where it is held by the air pressure in the accumulator.

With the system pressure trapped, the pressure regulator directs the output of the pressure pump back into the reservoir. The fluid circulates with very little load on the pump.

As soon as fluid is demanded by the system, the pressure regulator directs the pump output back into the system.

Question 29

What does an accumulator do?

Answer 29

It allows an incompressible fluid such as oil to be stored under pressure.

The fluid stored in the accumulator under pressure is available to supplement the pump as an additional source of hydraulic power when heavy demands are placed on the system.

Question 30

What is a power pack?

Answer 30

a hydraulic power pack is a small, self contained hydraulic system that includes the reservoir, pump, selector valves, and relief valves all in one easy-to-service unit.

Question 31

What happens when a pump alternately picks up fluid and then air due to an insufficient supply of fluid?

Answer 31

The pressure gauge fluctuates.

Question 32

What does a micronic filter do?

Answer 32

prevents the passage of solids greater than 10 microns in size. (0.0003934 inch)