RHAG

Question 1

What does RHAG stand for ?

Answer 1

Rotary hydraulic arrestor gear

Question 2

What is the purpose and need of a RHAG

Answer 2

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

Question 3

What are the 6 major components of a rhag?

Answer 3

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

Question 4

What is the fluid housing filled with?

Answer 4

40% water and 60% AL39 mix

Question 5

What is the capacity of the fluid housing

Answer 5

340.95 litres (75 gallons)

Question 6

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

Answer 6

Via the filler pipe, ensures top bearing is lubricated

Question 7

What must you not do after an arrest ?

Answer 7

Remove filler cap due to scolding

Question 8

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

Answer 8

3.12 mm

Question 9

What is the rewind sprocket assembly ?

Answer 9

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

Question 10

How can you remove the cover without disturbing the bearing ?

Answer 10

2 diametrically opposed recessed bolts

Question 11

How does the pre tension mechanism work?

Answer 11

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

Question 12

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

Answer 12

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

Question 13

How do you release the pre tension

Answer 13

Rotate spring handle 180 degrees clockwise

Question 14

What is the purpose of a retrieve system?

Answer 14

To retract the tapes and hook cable after an arrest

Pre tension the arrestor gear

Question 15

What are the retrieve system components ?

Answer 15

Electric motor
Fluid coupling
Speed reducer

Question 16

What is the purpose of a backstop clutch

Answer 16

Prevent reverse rotation

Maintain pre tension in the system

Question 17

What is the purpose of the fluid coupling

Answer 17

Transmit torque form the motor to reduce the speed

Sets correct tension in the hook cable

Rescues starting load on motor

Reduces shock loading

Question 18

What is the fluid coupling operation

Answer 18

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

Question 19

What is the fluid coupling fluid efficiency effected by?

Answer 19

Oil level
Oil viscosity
Oil flow
Heat dissipation

Question 20

What is the tape packing and guidance system?

Answer 20

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

Question 21

What does the tape packing and guidance system consist of?

Answer 21

Pressure roller unit
Absorption sheave
Runway edge sheave

Question 22

How much pressure does the bungee cord apply?

Answer 22

4893N before tape is wound on

7784N when it’s fully wound on

Question 23

What is the purpose of the absorber sheave ?

Answer 23

Guide the tape on and off the drum

Ensures tape doesn’t twist

Question 24

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

Answer 24

10.7 m

Question 25

What is the purpose of the hook cable assembly

Answer 25

Allow the aircraft to engage with the RHAG

Question 26

What is the minimum height above the runway surface?

Answer 26

63.5mm

Question 27

What is the spacing between cable supports ?

Answer 27

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

Question 28

When you should replace a hook cable ?

Answer 28

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

Question 29

Name types of hook cable damage

Answer 29

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

Question 30

What are the 3 lengths of tapes

Answer 30

320m 347. 5m 390. 1m

Question 31

When should tapes be replaced

Answer 31

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

Question 32

What is the rhag operation

Answer 32

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