Page 781 - PPL-engelsk 2025
P. 781
Aircraft general knowledge
If there is sufficient vacuum on the system, the heading
gyro is a stable and reliable navigation aid.
An example of a heading indicator is shown on the right.
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8.12.9 Magnetic compass
The function of the magnetic compass is to show the aircraft’s heading in relation
to the direction towards magnetic north (MN).
The magnetic compass is a unique instrument. Independent of current and
vacuum. The only energy required is the earth’s magnetism. It is a very sensitive
instrument, and an aircraft can be a restless platform, but the compass is
indispensable.
The instrument housing is filled with liquid that, when temperature changes,
changes volume.
The reason why there is liquid in the compass in one or more places is that it, for
example, dampens the movement of the magnets, lubricates and prevents
corrosion.
On the left, at the back of the compass, there is a compensator that can be
compressed by overpressure in the instrument housing.
On the right, there is a schematic
diagram and on the next page an
example of the instrument itself.
Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 781
