CHAPTER 34
PAGE 5
PAGE DATE: 1. March 2011
MAINTENANCE MANUAL EXTRA 330LX
34-10-02 Altimeter
The altimeter is designed to measure pressure changes of the
atmosphere by means of an aneroid capsule, the pressure
changes corresponding to changes in altitude. In this instru-
ment the pinion shaft drives the pointer shaft of the large
pointer via gearwheels . Further gearwheels are used to move
the small pointer. The altimeter has a scale marked in feet (ft)
or meters (m). By turning the knob at the bottom left of the
instrument, the barometric pressure reading is set in milli-
bars and/or in.Hg.
Removal/Installation
1 Remove the instrument cover per chapter 31-10-03 (rear
altimeter only).
2 Remove the vinyl tube and the tube-to-pipe adapter if nec-
essary.
3 Remove the attachment bolts and clip nuts.
4 Remove the altimeter.
5 Install in reverse sequence of removal.
6 Perform an operation test.
34-10-03 Airspeed Indicator
The airspeed indicator shows the speed of the aircraft rela-
tive to the atmosphere. The airspeed indicator measures the
difference between pitot pressure and static pressure, the
former being picked up by the pitot tube 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 tube. The
sensing element of the airspeed indicator is an open dia-
phragm which senses internally the pitot pressure and exter-
nally 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 and gearwheels. The reading of the
airspeed indicator is in knots or (dual scale) in kts and km/h.
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