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Flashcards in Hydraulics - Gear Deck (30)
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1
Q

What is the purpose of having additional wheels/gear?

A

Better distribution of pavement loading

2
Q

What is the purpose of the squat switch?

A

Keeps the gear lever lock ‘locked’, therefore preventing gear retraction on the ground

3
Q

What happens if the squat switch is faulty?

A

The pilot can manually override the lever lock and retract the gear.

4
Q

What is the purpose of an air/ground logic system

A

Allows the aircraft to understand if it is airborne or on the ground, which will inhibit certain equipment (e.g. gear retraction).

5
Q

What is the purpose of sequencing valves?

A

Ensure gear deployment or retraction in the correct order. For example, door opens, gear retracts, then door closes.

6
Q

After takeoff and having retracted the gear, what position will the gear selector be placed in?

A

Off (not up). The ‘off’ position prevents excessive buildup of hydraulic pressure and reduces strain on the system.

7
Q

When the gear selector is placed in the ‘off’ position, what is holding the gear in place since the hydraulic pressure is released?

A

Mechanical locks.

8
Q

Explain the process during aircraft pushback

A

To prevent excessive loads/forces, a locking pin is put in place to prevent crew steering.

9
Q

What happens if the locking pin is not removed after pushback?

A

The crew will not have directional control of the nosewheel.

10
Q

What is an apex pin?

A

A pin used during towing operations (not pushback). It is stronger than the lockout pin, and is generally used due to the sharp turns required during towing.

11
Q

In some aircraft, the rudders do not control the nose wheel. Above what speed will rudder inputs be able to control the nosewheel?

A

Above 80kts (approx). Before this the tiller is required.

12
Q

What is the purpose of the tiller?

A

To allow sharp turns during taxi.

13
Q

When does the steering shutoff valve activate?

A

After takeoff to stop the wheels being turned after becoming airborne (wheels may not fit in wheel well).

14
Q

What system ensures that the wheels are straightened after takeoff?

A

The ‘auto-centre’ system, which uses cams to centre the nose-wheel.

15
Q

What is the follow-up linkage?

A

A system which aligns the steering tiller to neutral after takeoff so that the control correctly represents wheel position.

16
Q

Why does the main gear have steering ability?

A

To prevent excessive side loads, especially during low speed taxi.

17
Q

To try and prevent excessive side load stress on the landing gear, what can pilots do?

A

Avoid sharp turns, especially at low speed.

18
Q

What direction does the body gear turn?

A

Opposite to the nose gear

19
Q

When is body gear steering armed?

A

During taxi (usually off during takeoff / landing)

20
Q

What is the purpose of tilting trucks?

A

Allows wheels to fit into smaller wheel wells

21
Q

What happens if the tilt actuator is inoperative?

A

Caution should be used, as damage can occur if the gear does not tilt into the correct position to fit into the wheel well.
A second problem is that some air/ground logic systems rely on the titl system functioning.

22
Q

What are the two faults which could prevent the landing gear not being retracted properly?

A

body steering not centred, and tilt actuator not working properly. Note that the pilot can override the system and retract the gear if required.

23
Q

Are there any alternate means of gear retraction/extension

A

There is no system for retraction (i.e. if no hydraulics, gear won’t retract).
But for gear extension, an electric system acts as a backup.

24
Q

For aircraft with 3 sets of landing gear (nose and main gear), there are 3 lights. What about aircraft with 5?

A

Just 1 light….seriously.

25
Q

A rear trailing bogie (rear wheels tilted like the A330) is beneficial because it…

A

Reduces tendency for the nose gear to slam into the ground (i.e. smoother landings)

26
Q

If a thermal plug melts causing the tyres to deflate, can they just be pumped up again?

A

No, they should be replaced.

27
Q

What is the point in having grooves on the tyres?

A

Deflect water away from the engine intake

28
Q

Is it normal for the pilot’s brakes to shudder during auto-brake operation?

A

Yes, this is due to the brakes being ‘modulated’, causing pulses in the hydraulic fluid which is transferred to the pilot pedals

29
Q

What is the minimum water depth which may lead to hydroplaning?

A

6mm

30
Q

What is the main factor affecting hydroplaning?

A

Tyre pressure. 9 x square root of tyre PSI for rotating wheel, and 7 x square root of tyre PSI for non-rotating. Indicates that non-rotating wheel more likely to hydroplane.