CHAPTER TWENTY TWO
T-34C AIRCRAFT SYSTEMS FAMILIARIZATION
The supply control lever is green and turns the regulator on and off. When aft in the OFF
position, no oxygen enters the regulator; when forward in the ON position, low pressure (70 PSI)
oxygen enters the cockpit regulator. The supply control lever should be "shear-wired" to the ON
position (See Figure 2). The diluter control lever is white and labeled 100% OXYGEN and
NORMAL OXYGEN. It selects 100% or diluted oxygen for delivery to the mask. When
forward in the 100% OXYGEN position, the mask receives undiluted and unpressurized oxygen;
when aft in the NORMAL OXYGEN position, the mask receives diluted and unpressurized
oxygen. The emergency pressure control lever is red and labeled EMERGENCY, NORMAL,
and TEST MASK. When forward in the EMERGENCY position, 100% oxygen is delivered to
the mask under a safe positive pressure irrespective of the diluter control lever. In the aft TEST
MASK position which must be held, 100% oxygen under positive pressure is delivered to the
mask. In the center NORMAL position, the mask receives oxygen with a composition as
selected by the diluter control lever.
A pressure gauge is located in the forward right corner of each control panel. Labeled OXYGEN
CYLINDER PRESSURE, it indicates supply cylinder pressure. The scale reads 0 - 2,000 PSI in
100 PSI increments. Acceptable pressure for flight is 1000 - 1850 PSI.
A blinker type flow indicator is located in the forward left corner of the panel. It indicates
oxygen is being released from the cockpit regulator to the mask. The blinker-vane will show
either black or white: black when no oxygen is released and white when oxygen is released.
Aviators' breathing oxygen is 99.45% pure oxygen. Pure oxygen under pressure will ignite
grease or oil spontaneously. Facial skin burn may result if oxygen and petroleum-based facial
products come in contact. Also, do not smoke while oxygen is in use.
High Pressure Relief Valve
A high pressure relief valve is located at the cylinder outlet to protect the supply cylinder against
damage caused by excessive pressure. At excessive pressure the relief valve opens and a plastic
blowout disc located above the flap on the right side of the aircraft is blown out and all oxygen in
the cylinder is dumped overboard. Absence of the disc provides a visual indication that the
cylinder is empty.
To prevent cockpit regulator contamination, the diluter control lever must be placed in the 100%
OXYGEN position when the regulator is not in use.
22-4 T-34C OXYGEN SYSTEM