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UKCAA M11 CAT A1 > M11.13 > Flashcards

M11.13 Flashcards

1
Q
A
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2
Q

What are the main functions of landing gear on jet aircraft?

A

Supports weight, dampens vibrations, absorbs impact, prevents strain on wheels and tyres, enables steering, operates reliably in harsh conditions.

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3
Q

What are the three Main Landing Gear (MLG) configurations?

A
  • Tail wheel
  • Tricycle-type
  • Tandem
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4
Q

Describe the tail wheel configuration.

A

Main gear located forward of CG, supported by a tail wheel or skid, self-centering, steering via differential braking or rudder pedals.

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5
Q

What are the advantages of the tricycle-type landing gear?

A
  • Prevents ground looping
  • Allows more forceful braking
  • Forward vision is unobscured
  • Reduced drag during take-off
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6
Q

What is a bogie configuration in landing gear?

A

A configuration with multiple wheels on the main gear, often used in larger aircraft designs.

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7
Q

What characterizes the tandem landing gear configuration?

A

Main gear and tail gear aligned on the longitudinal axis, few aircraft use this configuration, common in gliders.

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8
Q

What is the difference between fixed and retractable landing gear?

A
  • Fixed: non-retractable, lighter, cost-effective for low-speed aircraft
  • Retractable: reduces drag for high-speed aircraft
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9
Q

What are the main components of a typical Main Landing Gear (MLG) assembly?

A
  • Shock strut
  • Side strut
  • Drag brace
  • Downlock assembly
  • Uplock assembly
  • Trunnion
  • Actuator
  • Torsion link
  • Wheel and tyre assemblies
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10
Q

What is the function of the trunnion in landing gear?

A

Connects the top of the leg to the wing structure and allows rotation into and out of the landing gear bay.

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11
Q

What does the shock strut consist of?

A
  • Outer cylinder
  • Inner cylinder
  • Hydraulic oil and nitrogen
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12
Q

What is the purpose of the torsion link damper?

A

Counteracts wheel shimmy.

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13
Q

How does the retraction mechanism work when landing gear is selected up?

A

Single acting hydraulic downlock actuator breaks the over-centre lock, allowing the gear to fold.

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14
Q

Fill in the blank: The shortening mechanism is used to decrease the overall length of the landing gear leg during _______.

A

[retraction]

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15
Q

What is the Nose Landing Gear (NLG) designed for?

A

It is steerable, has no brakes, and carries less load than main gears.

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16
Q

What is a centring cam in the context of Nose Landing Gear?

A

Aligns the nose wheels in preparation for retraction.

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17
Q

What are the two main classes of shock absorbers?

A
  • Solid
  • Oleo-pneumatic
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18
Q

What characterizes an oleo-pneumatic shock strut?

A

Dampens impact using oil and gas, consists of telescopic cylinders.

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19
Q

Explain the difference between the oleo-pneumatic strut without a gas or oil separator and with a separator.

A

Without separator: oil and gas mix. With separator: oil and gas are separated by a piston.

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20
Q

What is hydraulic dieseling?

A

Occurs when air mixes with hydraulic oil, causing combustion and potential hydraulic cylinder failure.

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21
Q

What happens to the gas inside the oleo-pneumatic strut during take-off?

A

Gas expands as the weight is unloaded, forcing fluid to transfer between chambers.

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22
Q

What is the function of the flutter valve in an oleo-pneumatic strut with a separator?

A

Acts as a one-way restrictor, allowing faster fluid transfer during initial compression.

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23
Q

True or False: The shock energy during landing is transferred throughout the airframe at the same rate as the impact pulse.

A

False

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24
Q

What happens to the gas pressure during recoil in a strut?

A

The gas pressure is higher than is required to support the load

This occurs because the load during recoil is reduced.

25
What is the function of the separator piston in a strut?
It is pushed up by expanding gas, forcing fluid from the lower chamber back through the flutter plate ## Footnote This action controls the rate of extension of the strut.
26
What is a liquid spring?
An oil-filled absorber used to dampen shocks during landing ## Footnote The principle involves oil movement through damping orifices.
27
How does a liquid spring respond to large shocks during landing?
Oil is compressed until its pressure exceeds the loading of the piston’s non-return valve spring ## Footnote This allows a larger volume of oil to be released, damping larger landing shocks.
28
What happens to oil during the recoil phase of a liquid spring?
Oil is forced back below the piston through small damping orifices
29
What is used to service main gear shock struts?
Nitrogen gas and specified hydraulic fluid ## Footnote The specified hydraulic fluid must be compatible to prevent seal deterioration.
30
Why must the correct hydraulic fluid be used in shock strut servicing?
Different fluids are not compatible and the wrong fluid causes the seals to deteriorate
31
What is dimension 'X' in the context of shock struts?
A measure of the extension of the inner cylinder ## Footnote It is measured between two points on the outer and inner cylinders.
32
How is dimension 'X' measured?
It is measured in inches or millimetres ## Footnote It is checked against a graph in the maintenance manual.
33
What must be done if the measured dimension 'X' does not agree with the value from the graph?
Nitrogen must be added or released
34
On some aircraft, what is dimension 'X' referred to as?
Dimension 'H'
35
What factors are considered to find the correct dimension in the maintenance manual graph?
* Measured gas pressure * Actual shock strut temperature
36
37
What type of system is most commonly used for landing gear retraction in aircraft?
Hydraulic system ## Footnote Some light aircraft may use electrical and pneumatic systems.
38
What is the purpose of positive mechanical locks in landing gears?
To secure each gear in the selected, retracted, or extended positions.
39
How is the landing gear control lever typically positioned?
Three positions: ‘Up’, 'Off', and 'Down'.
40
What prevents the landing gear from being inadvertently selected to up on the ground?
A latch mechanism.
41
What happens when the landing gear selector lever is placed in the off position?
It depressurises the landing gear system.
42
True or False: The landing gear selector lever can be moved up on the ground without any restrictions.
False.
43
What is the role of solenoid-operated latches in landing gear systems?
To stop the lever from being moved inadvertently.
44
What is a potential consequence of a failure in the electrical supply to the solenoid?
It would not affect the latch operation on the ground.
45
What is the function of sequence valves during landing gear retraction?
To control fluid flow and prevent gear from becoming jammed.
46
What must occur before selecting the main gear up?
The gear must be down and locked.
47
What does the gear actuator receive during retraction?
Pressurised fluid to the gear up side of the piston.
48
Fill in the blank: The landing gear must be ________ before it can be retracted.
down and locked.
49
What prevents gyroscopic forces on the gear during retraction?
Hydraulic pressure may be applied to the wheel brakes.
50
What engages the up-lock roller during gear retraction?
A spring-loaded up-lock hook.
51
What happens when the selector lever is moved to the gear-down position?
Pressurised hydraulic fluid flows to unlock the nose gear.
52
What ensures that the jack always moves under positive pressure during nose gear extension?
A one-way flow restrictor.
53
What is the preferred arrangement for emergency extension systems in large commercial transport aircraft?
Free fall system.
54
What is the function of the manual gear extension handle?
To mechanically release the gear uplock for freefall.
55
What is required before operating the emergency manual release handle?
The landing gear selector must be in the off position.
56
What do gear down-lock viewers allow the crew to do?
Visually inspect the gear down-locks from inside the aircraft.
57
True or False: In some designs, gear down-lock viewers are located outside the aircraft.
False.
58
What must be consulted for descriptions of operation and performance standards of emergency landing gear extension systems?
Aircraft Maintenance Manual (AMM).

UKCAA M11 CAT A1 (21 decks)

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