PROCEDURE FOR ALTIMETER AND R ATE OF CLIMB TEST, NEGATIVE ALTITUDE.

TM 55-4920-416-13

NAVAER 17-15C-539

Section IV

Paragraphs 4-44 to 4-52

5,280 feet above mean sea level. In a circumstance of this

The airspeed indicator pointer will rotate clockwise indicating

sort, the altimeter needle will read 5,280 feet if the barometric

an increase in simulated airspeed.

adjustment is properly set. Connect the test set to the

g. Open the PRESSURE increase control valve 3 until

instruments to be tested as indicated in paragraphs 4-34 and

the airspeed indicator pointer stabilizes at the required check

4-35.

point.

h. Stabilize the airspeed indicator at the required check

4-44. PROCEDURE FOR ALTIMETER AND R ATE OF

points by opening the PRESSURE decrease control valve 4.

CLIMB TEST, NEGATIVE ALTITUDE.

i. After completing all check points listed on the

a. Set barometric indicator on Altimeter to 29.92.

airspeed Indicator calibration card, throw power switch to OFF.

b. Set barometric indicator on Altimeter being tested or

j. Slowly o pen PRESSURE control valves 3 and 4 until

calibrated to 29.92.

all instruments return to normal.

c. Set PRESSURE selector valve at NEGATIVE

k. Set PRESSURE selector valve at OFF.

ALTITUDE.

d. Close PRESSURE control valves 3 and 4.

4-49. CALIBRATE AIRSPEED INDICATOR, 50-650 KNOTS.

e. Set VACUUM selector at OFF.

Adjust PRESSURE control valves 3 and 4 in accordance with

f. Open VACUUM control valves 1 and 2.

paragraph 4-48. Set the master airspeed indicator at each

g. Throw power switch to ON.

point shown on the calibration card. Enter the readings of the

h. Slowly open the PRESSURE increase control valve 3.

instrument under test on the calibration test card provided.

The altimeter pointer will rotate counterclockwise indicating a

decrease in simulated altitude. At the same time, the rate-of-

4-50. CASE LEAK TEST, AIRSPEED INDICATOR.

climb indicator will move into the DIVE region.

a. Adjust pressure control valves in accordance with

paragraph 4-48 and stabilize the airspeed indicator at 500

knots.

CAUTION

b. Close needle valve on hose assembly to instruments

Use extreme care when conducting this

being tested.

test. If the altimeter goes below -1,000

c. Observe the airspeed indicator being tested; the

feet the altimeter will be damaged. Do

pointer should not move more than 4 knots in 60 seconds. A

not exceed 6,000 fpm during this test or

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

the rate-of-climb indicator will be

necessitate removal of the instrument.

damaged.

d. Slowly open needle valve on hose assembly to

i. Stabilize the altimeter at the required check points by

instruments being tested.

slowly opening the PRESSURE decrease control valve 4.

e. Return master instruments to normal position

j. After comple ting all check points listed on the

according to instructions in paragraph 4-48.

altimeter calibration card, throw power switch to OFF.

k. Slowly open PRESSURE control valves 3 and 4 until

4-51. Remove test hose connections in accordance with

all instruments return to normal.

paragraphs 4-34 and 4-35.

l. Set PRESSURE selector valve at OFF.

4-52. MAXIMUM ALLOWABLE AIRSPEED TEST. To test

4-45.

CALIBRATE ALTIMETER, NEGATIVE ALTITUDE.

and calibrate the Maximum Allowable Airspeed point on

Adjust PRESSURE control valves in accordance with

Mach-Airspeed indicators, make use if the master panel

paragraph 4-44. Set master altimeter at each point shown on

ALTIMETER and AIRSPEED INDICATOR on the VPT-7A Test

calibration card down to and including -1,000 feet. Enter the

Set, and proceed as follows.

readings of the instrument under test on the calibration test

card provided.

NOTE

The MACH-AIRSPEED INDICATOR with

4-46. Remove test hose connections in accordance with

MAXIMUM

ALLOWABLE

AIRSPEED

paragraphs 4-34 and 4-35.

POINTER, to be tested and calibrated,

usually has two adjustments, one at the

4-47.

AIRSPEED INDICATOR TEST, 50-650 KNOTS.

front lower left hand corner and one at

Connect the test set to the instrument to be tested as indicated

the rear. The front adjustment sets a

in paragraphs 4-34 and 4-35.

limiting stop for the maximum allowable

airspeed pointer, the rear adjustment sets

4-48. PROCEDURE FOR AIRSPEED INDICATOR TEST,

the critical Mach number for the aircraft

50-650 KNOTS.

on the rim of the main outer dial. Before

a. Set PRESSURE selector valve at airspeed 0-650

proceeding with tests, make sure that

knots.

these two adjustments have been

b. Close PRESSURE control valves 3 and 4.

properly set in accordance with data

c. Set VACUUM selector valve at OFF.

supplied for the aircraft using the

d. Open VACUUM control valves 1 and 2.

instrument.

e. Throw power switch to ON.

f. Slowly open the PRESSURE increase control valve 3.

a. Connect both the ALTIMETER-RATE-OF-CLIMB and

AIRSPEED quick connect nipples of the Test Set to the Static

and to the pressure lines respectively of the instrument