The benefit of automotive safety features in general aviation have persuaded the FAA to grant Terrafugia a waiver of weight and stall-speed limits so it can self-certify its Transition flying car as a light sport aircraft (LSA).
The Woburn, Massachusetts-based startup applied for the waiver in 2014 when it became clear that meeting highway-safety requirements would drive the gross weight of its roadable aircraft above the 1,320-lb. limit for LSAs, and push stall speed above the 45-kt. maximum.
Terrafugia applied for a waiver to allow an 1,800-lb. gross weight and 54-kt. stall speed on the basis that automotive occupant-protection features, including a safety cage and energy-absorbing crumple zones, would increase safety over that available in general-aviation aircraft.
By granting the waiver, the FAA has accepted Terrafugia’s arguments that design features required to meet federal motor-vehicle safety standards will provide substantial safety benefits over typical LSAs, and the exemptions to weight and stall limits “are in the public interest.”
The FAA previously granted Icon Aircraft an exemption to the LSA rules to increase the gross weight of its A5 amphibian by 250 lb. to 1,680 lb., on the basis of a spin-resistant wing design that increases safety.
In its 2014 petition, Terrafugia said structural and nonstructural occupant-protection systems added 52 lb. to the Transition’s gross weight, plus 266 lb. for roadability systems, such as steering, suspension and drive systems, that enable a pilot to land and continue a journey by road in poor weather.
A ballistic recovery parachute added 36 lb., for a total weight penalty over a conventional LSA of 480 lb., including a contingency margin. This growth in weight drove stall speed higher, because constraints such as lane width, parking space and garage height prevent the folding wing being increased in size.
Terrafugia began development of the Transition in 2006, flying a proof-of-concept aircraft in 2009 and a second-generation prototype in 2012. A third-generation conforming prototype is under construction for testing in 2016–17, with deliveries planned to begin following completion of this testing.
LSAs are self-certified to industry standards by their manufacturers, a process also used by automakers to show their products comply with highway-safety standards. In Terrafugia’s case, the Transition will have to meet the safety standards for truck-based multipurpose passenger vehicles.