INDICATORS.

TM 55-4920-416-13

NAVAER 17-15C-539

Section IV

Paragraphs 4-11 to 4-18

adjacent to the switch tells the operator that the unit is

4-13. ALTIMETER (9, figure 4-1). This altimeter has a useful

operating.

range from 1,000 feet below mean sea level to 80,000 feet

above mean sea level. A barometric correction scale is part of

4-11. INDICATORS.

the altimeter.

4-12. RATE OF CLIMB (8, figure 4-1). This instrument

4-14. AIRSPEED (KNOTS) (10, figure 4-1). This instrument is

displays the rate of climb or descent in fpm according to the

a sensitive type which reads accurately over its full range of 50

rate of increase or decrease of the vacuum produced by the

to 650 knots.

test set. Vacuum is proportional to altitude; hence, a change in

vacuum is sensed by the rate-of-climb indicator as a change in

4-15. MANIFOLD PRESSURE (11, figure 4-1). This gauge is

altitude. The calibrated range of the indicator is 0 6000 fpm.

of the absolute pressure type, reading from 10 inches to 75

The instrument is designed to tolerate greater rates of change

inches of Hg, with 30 inches of Hg representing mean sea

for short periods of time, without damage.

level. When used at sea level, an indication below 30 inches

of Hg represents a vacuum in the test set. An indication above

30 inches of Hg represents a pressure in the test set.

CAUTION

4-16. FUEL PRESSURE (12, figure 4-1). This gauge is a

It should be noted however that a sudden

direct reading instrument, calibrated from zero to 25 psig.

buildup to high vacuum (high altitude) or

conversely a sudden drop from high

4-17. TEST SET CONNECTIONS.

vacuum to low vacuum (for example,

mean sea level), can damage the

4-18.

POWER CONNECTOR (1, figure 4-3).

Power

instrument and render it useless.

1. Power Connector

4. Airspeed

2. Fuel Pressure

5. Rate-of-Climb

3. Manifold Pressure

and Altimeter

Figure 4-3. Test Set Connections