CESSNA SECTION 7
MODEL 152 AIRPLANE & SYSTEMS
DESCRIPTIONS
1 July 1978 7-29
WARNING
PITOT HEATER MUST BE ON WHEN OPERATING BELOW 40OF IN
INSTRUMENT METEROLOGICAL CONDITIONS
The heated pitot system consists of a heating element in the pitot tube, a rocker-type switch
labeled PITOT HT on the left switch and control panel, a 15-amp circuit breaker under the
engine controls on the instrument panel, and associated wiring. When the pitot heat switch is
turned on, the element in the pitot tube is heated electrically to maintain proper operation in
possible icing conditions. Pitot heat should be used only as required.
AIRSPEED INDICATOR
The airspeed indicator is calibrated in knots and miles per hour. Limitation and range
markings (in KIAS) include the white arc (35 to 85 knots), green arc (40 to 111 knots), yellow
arc (111 to 149 knots), and a red line (149 knots),
If a true airspeed indicator is installed, it is equipped with a rotatable ring which works in
conjunction with the airspeed indicator dial in a manner similar to the operation of a flight
computer. To operate the indicator, first rotate the ring until pressure altitude is aligned with
outside air temperature in degrees Fahrenheit. Pressure altitude should not be confused with
indicated altitude. To obtain pressure altitude, momentarily set the barometric scale on the
altimeter to 29.92 and read pressure altitude on the altimeter. Be sure to return the altimeter
barometric scale to the original barometric setting after pressure altitude has been obtained.
Having set the ring to correct for altitude and temperature, read the true airspeed shown on the
rotatable ring by the indicator pointer. For best accuracy, the indicated airspeed should be
corrected to calibrated airspeed by referring to the Airspeed Calibration chart in Section 5.
Knowing the calibrated airspeed, read true airspeed on the ring opposite the calibrated
airspeed.
RATE-OF-CLIMB INDICATOR
The rate-of-climb indicator depicts airplane rate of climb or descent in feet per minute. The
pointer is actuated by atmospheric pressure changes resulting from changes of altitude as
supplied by the static source.
ALTIMETER
Airplane altitude is depicted by a barometric type altimeter. A knob near the lower left portion
of the indicator provides adjustment of the instrument's barometric scale to the current
altimeter setting.
VACUUM SYSTEM AND INSTRUMENTS
An engine-driven vacuum system (see figure 7-9) is available and provides the suction
necessary to operate the attitude indicator and directional indicator. The system consists of a
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