TM 5-1940-321-13&P
( 5 ) Observe the pressure gage reading. If pressure is correct, proceed to step (8)
below.
( 6 ) If pressure exceeds 280 mb (4.2 psi), release air from the intercommunicating
valve on the opposite side of the craft from the pressure gauge. Grip the valve
flywheel with your hand and pull it away from the buoyancy tube. Listen for the
sound of air being released. Observe the pressure gauge on the opposite
buoyancy tube as air is released. Release air until the gauge indicates a
pressure of 248280 mb (3.5 4.1 psi). Proceed to step ( 8 ) below.
( 7 ) If pressure is below 240 mb (3.5 psi), add air at the intercommunicating valve
on the opposite side of the craft from the gauge as follows:
(a) Remove the metal valve cap, insert the small end of the foot pump hose into
the valve, and connect the large end of the hose to the foot pump port
marked INFLATION.
(b) While observing the gauge, operate the foot pump smoothly until pressure is
240-280 mb (3.5 -4.1 psi).
( 8 ) Remove the pressure gauge and foot pump hose (if used) from the valves and
replace the metal valve cap. Tighten the calve cap firmly by hand.
( 9 ) Turn the flywheels of all gour intercommunicating valves so that the indicating
arrows point to the 6 o clock position (green area marked NAVIGATION).
( 10 ) Replace any intercommunicating valve metal caps and tighten them firmly by
hand. Snap the covers down over the four intercommunicating valves.
( 11 ) Replace the isolator clamps on the two inglation hoses that connect the upper
buoyancy tubes to the lower buoyancy tubes. The correct position for the
isolator clamps is in the center of the straight portion of the hoses below the
elbows. Tighten the wing nut firmly by hand until the hose is pinched flat.
b. Keel Pressure Check. Check keel pressure as follows:
NOTE:
The correct pressure for the keel is 220-240 mb (3.2 3.5 psi).
( 1 ) Check the pressure of the keel. Remove the metal valve cap from the keel
valve (accessible through the hole in the thrustboard).
( 2 ) Insert the pressure gauge firmly into the valve and observe the pressure.
( 3 ) If keel pressure is correct, remove the pressure gauge and proceed to step (6)
below.
5-6
