Purpose
The thrust balance air shutoff valve sends 8th stage air to the LPT thrust balance annulus to reduce axial loads on the number 1 bearing.
Location
The thrust balance air shutoff valve is on the aft HPC case at the
12:00 position. The valve is under the precooler air duct.
Thrust Balance Air Shutoff Valve
The thrust balance air shutoff valve is a poppet-type valve. A spring holds the valve closed. PS3 servo air holds the valve in the open position.
When the valve is fully open, a position indicator pin extends above the valve body.
Training Information Point
No rigging is necessary.
EFFECTIVITY BEJ ALL  75-33-00 
Page 4 
D633W101-BEJ  Sep 05/2002 

AIR -THRUST BALANCE CONTROL -THRUST BALANCE AIR SHUTOFF VALVE

EFFECTIVITY BEJ ALL  75-33-00 
Page 5 
D633W101-BEJ  Sep 05/2002