week 6 Flashcards
Use to prevent compressor stalls that occur when the compressor is not running at it’s design speed.
Anti-stall Devices
Where is the variable bleed valve located?
case of the compressor
Purpose of a variable bleed valve?
To prevent compressor stalls below 91%
What is bleed valve consist of?
Consists of a pressure operated piston sliding on a guide pin.
P3 pressure is always _____ than P2.5
higher
What is Modified P3 air pressure?
air pressure below the diaphragm
what will rise if bleed valve is open longer?
EGT
Is the bleed valve diaphragm replaceable?
Yes
Is the bleed valve orifice replaceable?
No, they are matched to the bleed valve
What happens when the main orifice is blocked/restricted?
Valve will stay open longer
What happens If diaphragm is ruptured?
Valve will stay open longer
If convergent divergent orifice is blocked or restricted bleed valve will stay?
closed or close early.
Similar to the bleed valve except that with this system, air is bled from the rear stages of the compressor through the use of a band around the compressor, rather than a single valve.
Variable Bleed Bands
What kind of aircraft engine uses “Pressure Ratio Bleed Control Systems.”?
Larger Turbo Fan Engines
How many bleed valves are there on the JT8D engine?
3
Where are the valves located?
2 are on the 13th stage and 1 on the 8th stage of the high pressure compressor
These type of bleed valves are frequently used on large turbo fan engines and operated by the FADEC and EEC.
Transient bleed valves
To reduce rotational friction, the inlet guide vanes and stator vanes rotate within?
Teflon sockets
Where do you control the Variable Inlet Guide Vanes and Variable Stator Vanes?
main engine Fuel Control Unit
Information regarding the position of the VIGV / VSV is provided back to the FCU through the use of a?
Feedback cable
