Page 723 - PPL BEG-engelsk

Aircraft general knowledge

8.7 The vacuum pump

Aircraft are usually equipped with one or more vacuum pumps. The vacuum
pump usually drives the attitude indicator and the direction indicator.

For safety reasons, the last gyro, the turn coordinator, is powered by electricity.

This means that if you lose your vacuum, you can fly instrument flights using the

turn coordinator and the other instruments.

There is usually a vacuum pump that is powered by the aircraft's engine. On

more advanced aircraft, which have a greater need for the gyro instruments to

always work, there may be back-up systems.

If there is low suction/ vacuum, the gyro instruments will not function optimally.

You can look at the indicator to see if there is too low vacuum. This can also be
checked by lifting the nose of the aircraft quickly. If the artificial horizon shows

a roll, it may be a sign of low vacuum (or instrument failure).

You can see the vacuum

system in the illustration on
the right.

Back to table of contents

Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© marts 2026 723