TM 55-4920-231-14
f. Fuel Pressure Gage Tests
(9) Turn pressure DECREASE knob (11)
to open valve and allow reading on airspeed in-
(1) Place VACUUM selector knob (20, fig-
dicator (6) to return to normal.
ure 7) in OFF position and turn knobs (17 and
(10) Stop the tester (paragraph 27).
19) to open valves.
h. Airspeed Indicator Vacuum Test.
(2) Place PRESSURE selector knob (10) in
(1) Place VACUUM selector knob (20, fig-
FUEL PRESSURE position and turn knobs (11
ure 7) in AIRSPEED VACUUM SETTING and
and 12) to close valves.
turn knobs (17 and 19) to close valves.
(3) Place case leak valve levers (3, 4, 5, 7,
(2) Place PRESSURE selector knob (10) in
and 8, figure 8) in NOR position.
OFF position and turn knobs (1.1 and 12) to
(4) Start the tester (see paragraph 36).
open valves.
(5) Turn pressure INCREASE knob (12,
(3) Place case leak valves levers (3 and 4,
figure 8) in NOR position.
reach relief point and observing fuel pressure
(4) Open rear access panel (11, figure 4)
gage (5) reading. (Refer to table 3.)
and turn knob (14) to open safety valve (13).
(6) Turn pressure DECREASE knob (11)
Start the tester (paragraph 36).
to provide a stabilized reading of 20 psig on fuel
(5) Turn vacuum INCREASE knob (17,
pressure gage (5).
(7) Turn case leak valve lever (8, figure 8)
CREASE knob (19) to provide a stabilized read-
to CL position and observe fuel pressure gage
ing of 200 knots on airspeed indicator (6).
(5, figure 7) while timing for leakage. (Refer
(6) Turn knob (14, figure 4) to close
to table 3.)
safety valve (13) and observe airspeed indicator
(8) Slowly turn case leak valve lever (8,
(6, figure 7) reading while timing for leakage.
(Refer to table 3.)
INCREASE knob (12, figure 7) to close valve.
(7) Turn knob (14, figure 4) slowly to
(9) Turn pressure DECREASE knob (11)
open safety valve (13) when the leakage test has
been completed and close rear access panel (11).
to open valve and allow reading on fuel pressure
gage (5) to return to normal.
(8) Turn vacuum INCREASE knob (17,
(10) Stop the tester (paragraph 37).
CREASE knob (19) to open valve, allowing
g. Airspeed Indicator Pressure Tests.
reading on airspeed indicator (6) to return to
(1) Place VACUUM selector knob (20,
normal.
(9) Stop the tester (paragraph 37).
and 19) to open valves.
(2) Turn PRESSURE selector knob (10) to
20-250 KNOTS position and knobs (11 and 12)
CAUTION
to close valves.
Do not allow the altimeter reading to
(3) Place case leak valve levers (3, 4, 5, 7,
go below -1000 ft or the rate-of-climb
and 8, figure 8) in NOR position.
indicator to exceed 6000 fpm as it will
(4) Start the tester (paragraph 36).
damage the instruments.
(5) Turn pressure INCREASE knob (12,
a. Rate-of-climb Teat.
(1) Place VACUUM selector knob (20,
reach relief point and observing airspeed indi-
cator (6) reading. (Refer to table 2.)
and turn knobs (17 and 19) to close valves.
(6) Turn pressure DECREASE knob (11)
(2) Provide a zero reading on rate-of-climb
to provide a stabilized reading of 200 knots on
indicator being tested, with zero adjustment.
airspeed indicator (6).
(3) Place PRESSURE selector knob (10) in
(7) Turn case leak valve lever (4, figure 8)
OFF position and turn knobs (11 and 12) to
to CL position and observe airspeed indicator
open valves.
reading while timing for leakage. (Refer to
table 3.)
(4) Place case leak valve lever (3, figure 8)
in NOR position, case leak valve lever (4) in
(8) Slowly turn case leak valve lever (4,
CL position, and turn knob (14, figure 4) to
close safety valve (13).
INCREASE knob (12, figure 7) to close valve.
