I read an interesting accident report from the Air Accident Investigation Unit (AAIU) Ireland about an Avid Flyer kit aircraft - where the owner installed a 1.8 liter Subaru engine. During a flight the radiator cooling system burst and sprayed the cabin with coolant and fumes, the pilot successfully landed the plane, but it sustained significant damage.

Avid Mk. 4 Flyer EI-HAM

The ensuing investigation revealed that the thermostat was leaking causing the cooling system to over-cool the engine during previous flights, in an attempt to rectify the problem, the pilot covered the back side of the radiator with duct tape to reduce cooling. During the accident flight, the cooling system over heated, burst and filled the cockpit with coolant and fumes obscuring the instruments and the pilots vision.

Luckily both occupants survived, albeit with serious injuries. The AAIU made the following recommendation based on their investigation:


The Irish Light Aviation Society advise its members of the risks associated with carrying out unauthorised modifications to aircraft operating under a Flight Permit. (IRLD2011010)

Read the AAIU report here.