Damage limitation

A system of sensors that can automatically inspect aircraft structures for damage has undergone its first trial on a BAE Systems Hawk jet trainer.

The Advanced Structural Health Monitoring System (AHMOS), developed under a European Research and Development-funded initiative led by BAE, allows information gathered from an inspection performed by sensors to be downloaded on to a computer.

According to the company the new monitoring system could drastically reduce the time and costs of necessary structural inspection of military and commercial aircraft by locating the damage from its onset.

‘The new system aims to avoid lengthy and expensive structural inspections that require the repeated dismantling of large sections of aircraft. Very often such inspections are precautionary, and no faults that need repairing are found,’ said Jim McFeat, AHMOS technical manager at BAE Systems.

This means that if the sensor was able to accurately identify the location of damage deep inside an aircraft’s body, the need to take the airframe apart and scour it for damage would be reduced. The company estimated that this could save many millions of pounds over the lifetime of a fleet.

During the flight test, a self-contained capsule containing the acoustic emission detection platform, which senses impairment from the ultrasonic waves created by the growth of cracks, was attached to the underside of the Hawk (see below).

‘Using a combination of strain gauge sensors (which measure stress generated by structural components) and fibre-optic cables connected to a computer, and contained within an aerodynamic pod under the fuselage of the Hawk, we have now demonstrated that the technology works,’ said McFeat. ‘The customer will plug a computer into a data box on the aircraft and download inflight information gathered from gauges and sensors at strategic points.’

AHMOS has so far been demonstrated in two flights, and BAE Systems is planning another three before issuing a formal report in early 2008.