The Airtruk is a shoulder-wing strut braced sesquiplane of all-metal construction, with the cockpit mounted above a tractor-location opposed-cylinder air-cooled engine and short pod fuselage with rear door.

Because the name "Airtruck" was registered by the New Zealand companies Bennett Aviation Ltd and Waitomo Aircraft Ltd, for their PL-11, Transavia found another name for their PL-12 ("Airtruk").

Assistance was provided by the Aeronautical Research Laboratories (ARL) of the Defence Science and Technology Organisation (DSTO) and extensive tests carried out on the ground and in subsequent flight flutter clearance trials.

[3] An isolated flutter incident was reported in 1986 involving violent oscillations of the rudder and tail boom on the T-400 during a delivery flight.

Prior to this, the aircraft had relied on frictional damping provided by the lengthy control cables.

The modified aircraft was tested both on the ground and in flight trials in March 1988 over Port Philip, near Melbourne, Australia.

Oscillations were induced with an air operated tool fitted with an out-of-balance rotating mass.