Testing and development of a new warning system for low G-suit pressure in JAS 39 Gripen

Christer Berglund, Saab Aeronautics, Linköping, Sweden
Johan Sjöstrand, Saab Aeronautics, Linköping, Sweden

Abstract

To say that pilots were gods, the question about anti-G suit pressure or not, would be negligent... but they are not and therefore dependent of anti-G pressure supplying the anti- G suit. Modern aircraft expose pilots for accelerations of 1 to 9 G in just seconds. In the Gripen aircraft the pilot is exposed to high loads for long periods of time. Therefore the Anti- G protection is very important. Low pressure or loss of pressure in the anti-G suit at high Gloads is very severe and could lead to a fatal accident. As in all fighters with analogue equipments such as hoses, valves and sensors, loss of G-suit pressure could be a reality and this has in fact occurred in the Gripen aircraft a few times. Fortunately, no severe incidents occurred on these occasions.

Due to these incidents with loss of anti-G suit pressure and since there is no warning for low pressure, it was decided to implement a new warning system that warns the pilot in case of low anti-G suit pressure.

This paper describes the design, development and testing of the warning system as follows: Dynamic Flight Simulator with pressure drops introduced in the anti-G suit during high Gloads. Flight simulator tests to develop and verify the software before the flight testing. Flight tests in test aircraft and production aircraft. Parameters that had to be considered in the warning algorithm to avoid nuisance warnings. Description of pressure drops in the anti-G suit during high G-loads and a G-loc from the pilot’s perspective.