Engine System

Question 1

What purpose do the variable inlet guide vanes and air bleed valves serve?

Answer 1

Reduce the possibility of compressor stalls

Question 2

The T-38C anti-ice system prevents ice from forming on:

Answer 2

The inlet guide vanes and bullet nose

Question 3

How will the anti-ice system be affected with an AC power failure?

Answer 3

Anti-ice will be fully effective on any engine above 80% RPM

Question 4

What is the purpose of the variable exhaust nozzle?

Answer 4

Maintains maximum thrust efficiency while controlling EGT

Question 5

Under what atmospheric conditions should you use the anti-ice system?

Answer 5

• When temperature is near or below 32 °F

- In visible moisture or conditions of high humidity

Question 6

What is the point of the anti-ice system?

Answer 6

Fail safe system with 80% RPM minimum for effective anti-ice

Question 7

The primary advantage of using an afterburner in engine design is

Answer 7

High thrust for low weight

Question 8

How are the engine nozzles controlled?

Answer 8

• The throttle position closes the nozzles as RPM is increased up to approximately 97%.
• The T5 system opens the nozzles to maintain EGT between 630 – 650 °C in MAX power
• The T5 system only operates to maintain EGT within proper limits

Question 9

How can you be relatively sure the T5 system on a particular engine is working?

Answer 9

• Observe EGT indications between 630 – 650 °C in MAX power

- Check to see the nozzles open while advancing the throttle from 97% RPM to MIL power

Question 10

What electrical source is required to operate the T5 system?

Answer 10

An independent AC T5 alternator

Question 11

What is the correct nozzle position for military power?

Answer 11

0 to 20%

Question 12

What are the nozzle limits in maximum afterburner in flight?

Answer 12

50 to 85%

Question 13

If a sudden change of ________ psi or greater in oil pressure indication occurs at any stabilized RPM, follow the engine oil system malfunction procedures in Section III of the T-38C checklist

Answer 13

10

Question 14

During the lineup check at military power, which of the following engine instrument indications would be incorrect and unacceptable?

a. RPM — 100%
b. Oil pressure — 25 psi
c. EGT — 640 °C
d. Nozzle — 25%

Answer 14

Nozzle — 25%

Question 15

How is the engine rotated for starting during a ground start?

Answer 15

Low-pressure air

Question 16

In the event of an engine oil system malfunction

Answer 16

• Retard throttle to OFF if 0 to 20 psi cannot be maintained

- You may restart the engine at a later time

Question 17

What does the main fuel control computer do?

Answer 17

• The main fuel control positions the inlet guide vanes and bleed ports
• The main fuel control computer schedules the variable geometry system

Question 18

What happens if one afterburner blows out during takeoff, just prior to liftoff?

Answer 18

The nozzle will close and that engine will revert to MIL power

Question 19

Maximum fuel flow for start prior to ignition is:

Answer 19

360 pph

Question 20

Where is the fuel flow stopped when the engines are shut down after a normal flight?

Answer 20

• Fuel shutoff valve

- Main fuel control

Question 21

What conditions must exist before fuel will flow to the afterburner pump?

Answer 21

• The throttle must be placed in the MAX range

- Stabilized RPM at MIL

Question 22

During engine start, abort the start if EGT reaches ________ to prevent exceeding temperature limits of ______.

Answer 22

845 °C, 925 °C

Question 23

How are the fuel shutoff valves controlled?

Answer 23

Fuel shutoff switch position and the throttles

Question 24

True or false: To obtain ignition during a ground start (no APU), you must have the battery switch ON, push the start button, and place the throttle in IDLE

Answer 24

True

Question 25

True or false: A compressor stall is defined as the disruption of airflow through the compressor and can be caused by ice ingestion, bird ingestion, or afterburner initiation out of the engine envelope

Answer 25

True

Question 26

While flying at FL390, you advance the throttles and encounter a compressor stall. What should you do?

Answer 26

Quickly retard the throttle(s) to IDLE, push the start button, and then re-advance the throttle slowly while increasing airspeed. If engine damage is suspected, advance the throttle above idle only if required

Question 27

What is the recommended altitude and RPM for a successful airstart with JP-8/Jet A fuel?

Answer 27

Below 25,000 feet with 12% RPM minimum

Question 28

During an alternate airstart, how long does ignition occur?

Answer 28

30 seconds while in maximum throttle position

Question 29

If the left engine is restarted first after dual-engine flameout, what is the first indication of a start?

Answer 29

RPM increasing

Question 30

With complete electrical failure (battery dead), which engine instruments provide accurate information?

Answer 30

None. Tachometer sensors are independent, but EED is blank with DC power failure

Question 31

What would be the most likely malfunction when you observe the following conditions at MIL power: RPM decreasing to zero, oil pressure decreasing to zero, nozzle position zero, EGT at 650 °C, and fuel flow within limits?

Answer 31

The oil pump drive shaft has failed

Question 32

Why is it unnecessary to wait 30 seconds between air-starting the right and left engines?

Answer 32

Ram air is providing windmilling RPM to both engines simultaneously. The static inverter will provide ignition to both simultaneously