Airspeed Indicator Pressure Tests.

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 7) to open valve, allowing pressure to

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).

figure 7) to open valve and adjust vacuum DE-

(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.

figure 8) to NOR position and turn pressure

(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).

figure 7) to close valve and turn vacuum DE-

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.

figure 7) in OFF position and turn knobs (17

(9) Stop the tester (paragraph 37).

and 19) to open valves.

(2) Turn PRESSURE selector knob (10) to

40. RATE-OF-CLIMB INDICATOR TESTS

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.

figure 7) to open valve, allowing pressure to

(1) Place VACUUM selector knob (20,

reach relief point and observing airspeed indi-

figure 7) in ALT & R.O.C. 0-50,000 FT position

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

figure 8) to NOR position and turn pressure

close safety valve (13).

INCREASE knob (12, figure 7) to close valve.