Engine and Fuel Systems

Question 1

What does the engine-driven fuel pump do?

Answer 1

provides high pressure fuel to fuel control unit

Question 2

What happens if the engine driven fuel pump fails?

Answer 2

no engine

Question 3

What happens is speed lever is < 99.4%, the aircraft is faster than 50 kias and not in cruise mode?

Answer 3

“Speed lever - Low” warning in HDD

Question 4

At what RPM does the EFIU signal the ESM to open the fuel shutoff valve?

Answer 4

10% RPM

Question 5

Negative torque is generated when an engine flames out during flight and the propeller begins to windmill. The windmilling propeller will generate a large amount of drag until the propeller blades can be feathered. How does the NTS system provides temporary relief from this situation?

Answer 5

The NTS, by itself will cause blade pitch to cycle. As propeller RPM slows, the feathering valve will begin to close and the blade angle will begin to increase until propeller RPM gets too high, then the feather cycle will begin again.

Question 6

Closed loop power comes on automatically any time ______ hold is on.

Answer 6

altitude

Question 7

When failed torque loop or failed DEEC

mode, while altitude hold is on, the pilot’s engine speed command will be ignored and the engine will go to ___% RPM.

Answer 7

100%

Question 8

Engine speed control can be returned to pilot speed lever commands by turning off _______ hold.

Answer 8

altitude

Question 9

Closed loop power defaults to ON, but is not

active until…?

Answer 9

power level is at or above flight idle and engine speed is greater than 80%.

Question 10

During startup, a speed switch in the DEEC notifies the EFIU that engine RPM is above __%. The EFIU then sends an ignition activation signal to the ESM, which switches 28 VDC power to the ignition unit. A pilot indication of these events is ________and _________ just after reaching 10% RPM.

Answer 10

RPM is above 10%

positive fuel flow and a rise in EGT

Question 11

If RPM drops below ___%, it automatically performs an in-flight restart.

Answer 11

78%

Question 12

Based on OAT and density altitude, backup mode will limit power commands so that torque does not
exceed ___%.

Answer 12

70%

Question 13

Speed lever should be set to ___% before returning

to DEEC Mode from backup

Answer 13

100%

Question 14

What are the three ways the UARB network connects to the engine?

Answer 14

1. directly through the throttle and stop/feather servos
2. EFIU
3. DEEC

Question 15

What does the detent position of the condition lever do?

Answer 15

the fuel shutoff valve

Question 16

The critical speed range is from __% to __%.

Answer 16

18-28%

Question 17

How many fuel tanks?

Answer 17

7

Question 18

Where are vent valves located?

Answer 18

Vent valves are located in each fuel tank at the highest point in the tank and allow vapor in the tank to escape.

Question 19

Where do vapors collected in the vent box go?

Answer 19

left inboard

Question 20

When aircraft bank angle is __° or greater, the

tilt valve will keep the vent closed so that tank pressurization is not lost when the float drops due to bank angle.

Answer 20

10

Question 21

The DEEC controlled engine inflight ops range

Answer 21

82-100.5%

Question 22

DEEC lockout range

Answer 22

89.5-92.5% (DEEC will actually set 89% or 93%)

Question 23

Engine dry weight

Answer 23

375 lb

Question 24

Engine installed weight with prop

Answer 24

525 lb

Question 25

horsepower

Answer 25

900 SHP

Question 26

Jet thrust

Answer 26

157 lb max continuous

Question 27

total takeoff thrust

Answer 27

2000 lb (standard day, sea level)

Question 28

reverse thrust

Answer 28

700 lb (standard day, sea level)

Question 29

reduction gear box ratio

Answer 29

26:1

Question 30

The primary fuel nozzles use _______atomization while the secondary use ________atomization.

Answer 30

orifice and air blast

Question 31

what allows the fuel system to automatically provide extra fuel to the engine during startup without going through the fuel control unit?

Answer 31

enrichment circuit

Question 32

How many thermocouples comprise the EGT harness?

Answer 32

8

Question 33

how is EGT measured by the DEEC?

Answer 33

The delta pressure ratio transducer measures the ratio between compressor inlet px (Ps2) and the exhaust gas px (Ps5) and supplies the representative voltage to the DEEC. Actual EGT limits for the engine vary with temperature and density altitude. The DEEC calculated temp allows for one set of limits IE Single Red Line (SRL or SEGT) value. If DEEC fails or is disabled reference EGT limit chart in Section 5

Question 34

what does closed loop power do?

Answer 34

provides linear throttle response by using engine torque as a feedback signal and automatically adjusting engine power to match the throttle setting.

Question 35

closed loop power can be turned off by the pilot but comes on automatically when...

Answer 35

any time altitude hold is turned on

Question 36

if closed loop power becomes non-op, the pilots engine speed command will be ignored and the engine will go to ____% RPM. How can pilot regain control of the speed lever?

Answer 36

100. turn off altitude hold

Question 37

what is displayed in status area if C/L power is disabled or failed?

Answer 37

black text "power lever"

Question 38

C/L power defaults to on but is not active until...

Answer 38

power level is at or above flight idle AND engine speed is greater than 80%

Question 39

the ignition unit and starter are automatically deactivated at the end of the start cycle at ___% RPM

Answer 39

60

Question 40

If RPM drops below ___% inflight, the RCM sends a signal to the EFIU and an automatic restart is activated

Answer 40

78

Question 41

when DEEC in backup mode, power commands are limited as a function of _______ and ________ so that torque does not exceed ____ %

Answer 41

OAT and density altitude, 70%

Question 42

True/False. In backup mode, reverse thrust is limited

Answer 42

true

Question 43

The UARB network connects to the engine components in one of the following 3 ways:

Answer 43

directly to the throttle and stop/feather servos through the DEEC through the EFIU

Question 44

what does the condition lever do in the detent position?

Answer 44

closes the fuel shutoff valve

Question 45

what does the condition lever do in the full aft position?

Answer 45

mechanically feathers prop and closes the fuel shutoff valve

Question 46

what does the speed lever do?

Answer 46

sends RPM command to DEEC, DEEC controls torque motor which sets prop governor in order to achieve the commanded speed

Question 47

what does setting GCS ignition hot do?

Answer 47

activates the electric fuel pumps

Question 48

what is the critical speed range (RPM)?

Answer 48

18-28%. accel/deceleration through range is 1%/ second

Question 49

what happens during an inflight restart if RPM is less than 60%

Answer 49

EFIU turns on the unfeather pump

Question 50

what happens if the aircraft goes lost link with the engine shut down?

Answer 50

igniters are forced on and the system attempts a restart even if the engine was shut down prior to the lost link condition

Question 51

the outboard wing tanks ______ feed to the inboard wing tanks

Answer 51

gravity

Question 52

how many fuel tanks. where located?

Answer 52

7. 3 fuselage, 4 wing

Question 53

calculated fuel is computed by the RCM based on...

Answer 53

loaded fuel level minus flow rate data, then proportionately distributed to the tanks

Question 54

a red fuel leak warning occurs when...

Answer 54

wing probe indicates 200 lbs below calculated or forward/aft probe indicates 250 lbs below calculated

Question 55

which tanks have float switches?

Answer 55

forward, aft, and inboard wing tanks

Question 56

how many jet pumps? where are they located?

Answer 56

4. forward, aft and inboard wing tanks

Question 57

how many valves on fuel feed manifold?

Answer 57

4

Question 58

where is unused fuel from the header tank returned to?

Answer 58

the tank it came from via the return solenoid

Question 59

how many vent valves and where are they located?

Answer 59

in each fuel tank at highest point to allow vapor to escape

Question 60

any liquid collected in the vent box is routed to the...

Answer 60

inboard left wing tank

Question 61

forward tank fuel load

Answer 61

1300

Question 62

header tank fuel load

Answer 62

204

Question 63

aft tank fuel load

Answer 63

790

Question 64

wing tank fuel load (per side)

Answer 64

735

Question 65

unusable fuel

Answer 65

1-2% (60lbs)

Question 66

how is fuel level calculated after jettison?

Answer 66

known dump rate multiplied by time elapsed, then subtract from fuel quantity prior to jettison

Question 67

mass flow sensor is accurate to +/-

Answer 67

10lbs / hr

Question 68

how many watts are the electric fuel heaters? How many elements in each heater? When do they activate?

Answer 68

600 watts. 2 elements. 1st element on < 10C and off at >13 C for more than 10 sec. 2nd element on <5C and off >8C for more than 10 sec

Question 69

how many sides does the forward tank have?

Answer 69

2

Question 70

fuel is initially drawn from the ________ and ______ tank only over a ____ sec period. After two ____ sec cycles, fuel is drawn from the _______ and _____ tanks over a ____ sec period.

Answer 70

forward and wing tanks over 300 sec. 300 sec. forward and aft over 100 sec

Question 71

Fuel pumps are operated for _____ minutes each with a ____sec overlap

Answer 71

20 minutes. 10 sec

Question 72

If fuel feed px drops below ___ psi for more than __ sec, the RCM will perform a __ sec reset of the active fuel pump and reset the ___ min switching timer.

Answer 72

15psi, 5 sec, 1 sec, 20 min

Question 73

what happens after a second fuel pump reset cycle if pressure is still below 15 psi?

Answer 73

pump fail warning downlinked and both pumps commanded on for remainder of flight

Question 74

what happens if both elec pumps fail?

Answer 74

engine runs til fuel in header is depleted

Question 75

is it possible to jettison fuel with both elec pumps are failed?

Answer 75

no

Question 76

if header tank px exceeds X.X psi, Fuel Tank Header-over-pressurized downlinked to GCS

Answer 76

4.6

Question 77

if longitudinal CG is more than __ inches from set location or the lateral CG is more than __ in from set location a warning is downlinked to GCS

Answer 77

3 or 1