CHAPTER 34
PAGE 6
MAINTENANCE MANUAL EXTRA 300/SC
PAGE DATE: 16. June 2008
34-10-03 Airspeed Indicator
Description and Operation
The airspeed indicator shows the speed of the aircraft relative
to the atmosphere. The pitot airspeed indicator measures the
difference between pitot pressure and static pressure, the
former being picked up by the pitot head at the pitot location
of the air flow and applied to the airspeed indicator via
tubing, the latter also being picked up by the pitot head. The
sensing element of the airspeed indicator is an open
diaphragm which senses internally the pitot pressure and
externally the static pressure, the difference between the
two increasing with increasing speed. This difference
produces distortion of the diaphragm which is translated to
the pointer via a system of levers an gearwheels.
The reading of the airspeed indicator is in knots.
Max. operation altitude: 12,000 m
Operating temperature range: -30°C thru +50°C
Removal/Installation
1 Remove the vinyl tubing.
2 Remove the attachment bolts and nuts.
3 Hand the airspeed indicator under the instrument panel
and remove.
4 Install in reverse sequence of removal. Observe correct
installation of vinyl tubing: "Stat. Druck" = static pres-
sure, "Meßdruck" = Pitot pressure.
5 Perform an operation test.
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