Engine System Flashcards
What purpose do the variable inlet guide vanes and air bleed valves serve?
Reduce the possibility of compressor stalls
The T-38C anti-ice system prevents ice from forming on:
The inlet guide vanes and bullet nose
How will the anti-ice system be affected with an AC power failure?
Anti-ice will be fully effective on any engine above 80% RPM
What is the purpose of the variable exhaust nozzle?
Maintains maximum thrust efficiency while controlling EGT
Under what atmospheric conditions should you use the anti-ice system?
- When temperature is near or below 32 °F
- In visible moisture or conditions of high humidity
What is the point of the anti-ice system?
Fail safe system with 80% RPM minimum for effective anti-ice
The primary advantage of using an afterburner in engine design is
High thrust for low weight
How are the engine nozzles controlled?
- 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
How can you be relatively sure the T5 system on a particular engine is working?
- 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
What electrical source is required to operate the T5 system?
An independent AC T5 alternator
What is the correct nozzle position for military power?
0 to 20%
What are the nozzle limits in maximum afterburner in flight?
50 to 85%
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
10
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%
Nozzle — 25%
How is the engine rotated for starting during a ground start?
Low-pressure air
In the event of an engine oil system malfunction
- Retard throttle to OFF if 0 to 20 psi cannot be maintained
- You may restart the engine at a later time
What does the main fuel control computer do?
- The main fuel control positions the inlet guide vanes and bleed ports
- The main fuel control computer schedules the variable geometry system
What happens if one afterburner blows out during takeoff, just prior to liftoff?
The nozzle will close and that engine will revert to MIL power
Maximum fuel flow for start prior to ignition is:
360 pph
Where is the fuel flow stopped when the engines are shut down after a normal flight?
- Fuel shutoff valve
- Main fuel control
What conditions must exist before fuel will flow to the afterburner pump?
- The throttle must be placed in the MAX range
- Stabilized RPM at MIL
During engine start, abort the start if EGT reaches ________ to prevent exceeding temperature limits of ______.
845 °C, 925 °C
How are the fuel shutoff valves controlled?
Fuel shutoff switch position and the throttles
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
True
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
True
While flying at FL390, you advance the throttles and encounter a compressor stall. What should you do?
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
What is the recommended altitude and RPM for a successful airstart with JP-8/Jet A fuel?
Below 25,000 feet with 12% RPM minimum
During an alternate airstart, how long does ignition occur?
30 seconds while in maximum throttle position
If the left engine is restarted first after dual-engine flameout, what is the first indication of a start?
RPM increasing
With complete electrical failure (battery dead), which engine instruments provide accurate information?
None. Tachometer sensors are independent, but EED is blank with DC power failure
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?
The oil pump drive shaft has failed
Why is it unnecessary to wait 30 seconds between air-starting the right and left engines?
Ram air is providing windmilling RPM to both engines simultaneously. The static inverter will provide ignition to both simultaneously
