THRUSH S2R – G10 - Pressure Check Procedure

THRUSH AIRCRAFT INC – MODEL S2R G10
AIRCRAFT MAINTENANCE MANUAL
Page 5-12 Effective: 03/26/2010
pressure hose from the shut-off valve to a
wing fuel outlet, and connect the wing vent
line to the manometer inlet side. Plug the
other wing fuel outlet.
PRESSURE CHECK PROCEDURE
Crack the shut-off valve just enough to
hear air flowing through it. An increase in
pressure in the wing will be indicated by
movement of the manometer water column
up the scale side. While extreme pressure
build-up within the tank or fuel system is
prevented by the open-ended manometer
tube, too rapid of pressure build-up can
cause a pressure spike that can severely
damage the wing.
Apply pressure to the fuel tank
very gradually. Do not
pressurize the tank in excess of
44.0 inches of water or damage
may occur.
When pressure in the tank exceeds 38”,
start checking the tank for air leaks. Some
can be identified by hissing sounds and/or
feeling the air escaping. Feel sensitivity is
increased by wetting the hands. Leak
detection fluid will identify smaller leaks.
Turn the shut-off valve off before the water
column reaches 44”. The valve may need
to be re-opened to maintain at least 38”
while leaks are detected and solved.
Once all obvious leaks have been detected
and solved, a general check of all joints
and seams should be made using leak
detection fluid or soapy water.
When satisfied that all leaks have been
detected and solved, and with the
manometer reading between 38” and 44”,
close the shut-off valve. Start a stop-watch
or note the second hand position on a
watch and note the manometer reading.
CAUTION
After 5 minutes minimum has elapsed by
the watch, if the manometer reading has
not decreased by more than ¼” the
pressure check is successful. Leakage
greater than this necessitates finding and
solving the remaining leak(s).
Repeat this process until the wing holds
pressure as specified above.