EPU

Question 1

Hydrazine Leak detector

Answer 1

Mustard yellow under right wing through access door 3208 - turns purple/black when leak in fuel/EPU system

Question 2

EPU nitrogen bottle pushes ______ into EPU for EPU start and as required for normal EPU operations

Answer 2

Hydrazine

Question 3

EPU Fired indicator shows

Answer 3

3 balck triangles with 3 white triangles (grey - not fired)

Question 4

EPU automatic activation when:

Answer 4

main and stby generator failure, or Dual hydraulic system failures <1000psi

Question 5

HYDRAZN light

Answer 5

indicated EPU is commanding hydrazine, and indicated primary spped control failure

Question 6

AIR Light

Answer 6

when EPU commanded on with safety pin removed, stays on whole EPU augmented by hydrazine

Question 7

EPU run light

Answer 7

turbine speed is in proper range, and EPU driven hydraulic pump discharge pressure above 2000 psi

Question 8

only time hydrazine not required

Answer 8

EPU/GEN test switch

Question 9

EPU Fuel % remain

Answer 9

operates on battery bus power, ensure 95-102%

Question 10

purpose of EPU

Answer 10

provides hydraulic pressure to system A and Emergency electrical power to ac/dc busses but requires dc power from battery bus

Question 11

____ and _____ are unpowered when EPU operates

Answer 11

Nonessential and essential DC buses

Question 12

EPU requires ___ seconds to come up to speed, FLCS powered by _____ durig gen failure and _____ during engine failure during the spool up time

Answer 12

2 seconds ; FLCS PMG (pemanent magnetic generator) for gen failure ; Hydraulic system B for engine failure

Question 13

EPU Exhaust

Answer 13

Lower inboard side of right strake
Nitrogen,hydrogen,ammonia,water
can reach 1600 degrees
flammable
ammonia oder

Question 14

Hydrazine only mode time

Answer 14

<10 minutes, 15% per minute (if EPU is main source of hydraulic power, loss of EPU is loss of A/C control)

Question 15

engine bleed air for EPU helps____

Answer 15

minimize hydrazine use with thrust above 75% rpm

Question 16

________ moves control valves that keeps the EPU turbine power unit rpm constant by controlling the amount of bleed air or hydrazine

Answer 16

Electronic speed controller

Question 17

how do you know the tertiary system is controlling the speed controller?

Answer 17

blinking EPU run light, steady HYDRAZN light

Question 18

how does the EPU generator function

Answer 18

it powers the emergency ac and dc buses and the battery bus

Question 19

prior to EPU check make sure

Answer 19

EPU pin is inserted, 100% oxygen, EPU GEN/EPU PMG lights are off

Question 20

EPU check

Answer 20

ensure EPU pin is inserted and 100% Oxygen
EPU GEN/EPU PMG lights are off
EPU switch off
EPU safety pin removed
EPU NORM (once ground crew is out of the way)
Engine rpm - increase 5% above idle

Question 21

EPU/GEN TEST Switch

Answer 21

EPU/GEN TEST switch - EPU/GEN and hold
EPU AIR light - on
EPU GEN/EPU PMG lights - off
FLCS PWR lights - on (ABCD)

Question 22

EPU run light should stay on for ___ seconds, if it does not illuminate within ____ seconds, release the test switch, increase the throttle by 5%, and test again

Answer 22

5 second ; 10 seconds

Question 23

4 situations start the EPU automatically:

Answer 23

dual hydraulic failure (<1000 psi)
main and stby generator failure
engine lost
PTO Shaft Shear