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Aircraft Ancillary Equipment > RHAG > Flashcards

RHAG Flashcards

1
Q

What does RHAG stand for ?

A

Rotary hydraulic arrestor gear

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2
Q

What is the purpose and need of a RHAG

A

Automatically arrest the aircraft and prevent aircraft from over running the airfield

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3
Q

What are the 6 major components of a rhag?

A 
Energy absorption unit (EAUs)
Retrieve system
Tape packing and guidance system 
Tape end fitting
Electrical system 
Installation and siting
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4
Q

What is the fluid housing filled with?

A

40% water and 60% AL39 mix

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5
Q

What is the capacity of the fluid housing

A

340.95 litres (75 gallons)

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6
Q

How is the fluid in the fluid housing filled and checked ?

A

Via the filler pipe, ensures top bearing is lubricated

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7
Q

What must you not do after an arrest ?

A

Remove filler cap due to scolding

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8
Q

What is the clearance between the tape drum, lower flange and rollers?

A

3.12 mm

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9
Q

What is the rewind sprocket assembly ?

A

Mounted on EAU
Connected to speed reducer via a chain
Rotates tape drum during rewinds

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10
Q

How can you remove the cover without disturbing the bearing ?

A

2 diametrically opposed recessed bolts

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11
Q

How does the pre tension mechanism work?

A

The cam is held against the cam post when correctly tensioned

Aircraft overcomes the spring tension

Cam is snapped free of cam post

Tape drum can now rotate

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12
Q

How much force is required to overcome the pre tension spring ?

A

22,241N - 26,689N or 5000-6000lbs

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13
Q

How do you release the pre tension

A

Rotate spring handle 180 degrees clockwise

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14
Q

What is the purpose of a retrieve system?

A

To retract the tapes and hook cable after an arrest

Pre tension the arrestor gear

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15
Q

What are the retrieve system components ?

A

Electric motor
Fluid coupling
Speed reducer

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16
Q

What is the purpose of a backstop clutch

A

Prevent reverse rotation

Maintain pre tension in the system

17
Q

What is the purpose of the fluid coupling

A

Transmit torque form the motor to reduce the speed

Sets correct tension in the hook cable

Rescues starting load on motor

Reduces shock loading

18
Q

What is the fluid coupling operation

A

Motor rotates turning impeller
This forces oil outwards
Oil strikes vanes of casing

19
Q

What is the fluid coupling fluid efficiency effected by?

A

Oil level
Oil viscosity
Oil flow
Heat dissipation

20
Q

What is the tape packing and guidance system?

A

Ensure it’s wound on tightly
Wound on uniformly
Smooth pay out of tape
No snatching or jamming

21
Q

What does the tape packing and guidance system consist of?

A

Pressure roller unit
Absorption sheave
Runway edge sheave

22
Q

How much pressure does the bungee cord apply?

A

4893N before tape is wound on

7784N when it’s fully wound on

23
Q

What is the purpose of the absorber sheave ?

A

Guide the tape on and off the drum

Ensures tape doesn’t twist

24
Q

How far is the runway edge sheave located from the runway edge ?

A

10.7 m

25
Q

What is the purpose of the hook cable assembly

A

Allow the aircraft to engage with the RHAG

26
Q

What is the minimum height above the runway surface?

A

63.5mm

27
Q

What is the spacing between cable supports ?

A

0.9m from the middle of the runway and 1.8 after that

28
Q

When you should replace a hook cable ?

A

More than 2 wires broken in any strand
Worn 1/2 the diameter
More than 6 wires in one lay length
Excessive wear

29
Q

Name types of hook cable damage

A

Open strands
Kinking
30 or more flat spots of 12.5 mm Necking

30
Q

What are the 3 lengths of tapes

A

320m

  1. 5m
  2. 1m
31
Q

When should tapes be replaced

A

48 months or 100 arrests
Cut longer than 12 mm
25% failed stitching
Width is less than 5 1/2 inches

32
Q

What is the rhag operation

A
  1. A/C hook engages cable
  2. Tension increases in the cable and tapes
  3. tension overcomes the cam spring pressure
  4. drums rotate , turbulence in EAU causes breaking effect
  5. aircraft is smoothly stopped

Aircraft Ancillary Equipment (7 decks)

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