MACH INDICATOR TESTS.

TM 55-4920-416-13

NAVAER 17-15C-539

Section IV

Paragraphs 4-61 to 4-71

e. Throw power switch to ON.

h. Stabilize the fuel pressure indicator at the required

f. Slowly open the PRESSURE increase control valve 3.

check points by opening the PRESSURE decrease control

The manifold pressure indicator pointer will rotate clockwise

valve 4.

indicating an increase in simulated manifold pressure.

i. After completing all check points on the fuel pressure

g. Open the PRESSURE increase control valve until the

indicator, throw power switch to OFF.

manifold pressure indicator pointer stabilizes at the required

j. Slowly open PRESSURE control valves 3 and 4 until

check point.

all instruments return to normal.

h. Stabilize the manifold pressure indicator at the

k. Set PRESSURE selector valve at OFF.

required check points by opening the PRESSURE decrease

control valve 4.

4-66. CALIBRATE FUEL PRESSURE INDICATOR. Adjust

i. After completing all check points on the manifold

PRESSURE control valves in accordance with paragraph 4-65.

pressure indicator, throw power switch to OFF.

Set the master fuel pressure indicator at each point shown on

j. Slowly open PRESSURE control valves 3 and 4 until

the calibration card. Enter the readings of the instrument

all instruments return to normal.

under test on the calibration test card provided.

k. Set PRESSURE selector valve to OFF.

4-67. CASE LEAK TEST, FUEL PRESSURE INDICATOR.

4-61. CALIBRATE MANIFOLD PRESSURE INDICATOR,

a. Adjust PRESSURE control valves in accordance with

PRESSURE, 30 - 75 INCHES OF HG ABS.

Adjust

paragraph 4-65 and stabilize the fuel pressure indicator at 25

PRESSURE control valves in accordance with paragraph 4-59.

psig.

Set the master manifold pressure indicator at each point shown

b. Close needle valve on hose assembly to instruments

on the calibration card. Enter the readings of the instrument

being tested.

under test on the calibration test card provided.

c. Observe the fuel pressure indicator being tested; the

pointer should not move more than 1/2 psig in 60 seconds. A

4-62. CASE

LEAK

TEST,

MANIFOLD

PRESSURE

reading in excess of this indicates a possible case leak and will

INDICATOR, PRESSURE, 30 - 75 INCHES OF HG

necessitate removal of the instrument.

ABS.

d. Return instruments to normal position according to

a. Adjust PRESSURE control valves in accordance with

instructions in paragraph 4-65.

paragraph 4-60 and stabilize the manifold pressure indicator at

75 inches of Hg.

4-68. Remove test hose connections in accordance with

b. Close needle valve on hose assembly to instruments

paragraphs 4-34 and 4-35.

being tested.

c. Observe the manifold pressure indicator being tested.

4-69. MACHMETER TESTS. Machmeters and the Mach

The pointer should not move more than 1/16 inch of Hg in 60

Indicator portions of maximum allowable airspeed indicators, in

seconds. A reading in excess of this indicates a possible case

the range from Mach .3 to Mach 2.5 may be tested and

leak and will necessitate removal of the instrument.

calibrated by means of VPT-7A Test Set using its standard

d. Slowly open needle valve on hose assembly to

panel instruments, through the simultaneous use of the

instruments being tested.

pressure and vacuum sections of the test set and the altitude

e. Return instruments to normal position according to

and airspeed settings as given in Table 4-2.

instructions in paragraph 4-60.

a. Connect hose between the static outlet of the

instrument to be tested and the Altimeter - Rate-of-Climb

4-63. Remove test hose connections in accordance with

quick-connect nipple of the Test Set.

paragraphs 4-34 and 4-35.

b. Connect another hose between the pitot outlet of the

instrument to be tested and the airspeed quick-connect nipple

4-64. FUEL PRESSURE INDICATOR TEST. Connect the test

of the Test Set.

set to the instruments to be tested as indicated in paragraphs

4-34 and 4-35.

4-70. MACH INDICATOR TESTS.

4-65. PROCEDURE FOR FUEL PRESSURE INDICATOR

4-71. PROCEDURES.

TEST, 0 - 25 PSIG.

a. Set PRESSURE selector valve at FUEL PRESSURE.

NOTE

b. Close PRESSURE control valves 3 and 4.

Refer to Table 4-2.

Determine the

c. Set VACUUM selector valve at OFF.

working part of the table applicable to the

d. Open VACUUM control valves 1 and 2.

location of test and the range of the

e. Throw power switch to ON.

instrument to be tested as follows:

f. Slowly open the PRESSURE increase control valve 3.

The fuel pressure indicator pointer will rotate clockwise

a. Determine the approximate altitude of the location at

indicating an increase in simulated fuel pressure.

which the tests are to be performed.

g. Open the PRESSURE increase control valve 3 until

b. Table 4-2 will apply only to the right of the column

the fuel pressure indicator pointer stabilizes at the required

whose altitude is next above the approximate altitude of the

check point.

location of the test. For instance, where the test station is

located at an altitude of 1500 feet above sea level, the working

part of the chart will fall between columns 3 to 11.