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Adhesive bonding failure caused aircraft crash, report finds

AAIB The black aircraft after it had crashedAAIB
The aircraft was being flown at 30ft at the time of the crash

A failure of adhesive bonding was the cause of an aircraft crash, an investigation has found.

The Air Accidents Investigation Branch published its report on the VA-1X, G-EVTL crash at Cotswold Airport on 9 August 2023.

The aircraft was being flown by a remote pilot on an experimental test flight at 30ft (9m) above ground level when a propeller blade detached.

There were no crew or passengers on board and nobody was injured in the crash.

Routine checks had been made prior to take-off and the aircraft set up according to the test card.

It took off at 07:14 BST which was described as "a normal vertical take-off".

After the aircraft became stable, the remote pilot shut down an electric propulsion unit (EPU 1) in accordance with the test card.

The pilot then began a gentle climb to 9m (30ft).

There were eight EPUs on board, and all of them drove propellers.

Loud 'pop'

The test card required the aircraft to be stable at this height for 10 seconds before the flight could proceed.

After this was completed, the test pilot began a "gentle acceleration" towards seven knots ground speed (kt GS).

As the speed of the aircraft passed 2-4 kt GS, a loud "pop" was heard as a propeller blade was released from EPU3.

As a result, the aircraft was unable to stay in the air and struck the ground at 07:15 BST, three seconds after the noise was heard, on the southern edge of Runway 26.

The impact saw the right wing fail outboard of pylon three, in addition to the nose gear collapsing and other structural damage.

Two propellers detached from EPU3, with a blade sheath coming to rest 9m (30ft) from the aircraft.

The released propeller blade had been operating as normal but the "progressive degradation of the bond occurred during operation prior to the blade release".

The conditions on the day of the flight were "ideal", the report said, with light winds from the south west.

At the time of the flight, the aircraft's manufacturer was in the process of introducing a blade design that eliminated the bonding failure mode that caused the blade release.

Following its own investigation, it identified 36 improvements that could be made to products and processes.

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