N3165VRans S-12XL · 2000

On December 16, 2018, at 1530 eastern standard time, a Rans Inc. S-12XL experimental light sport airplane, N3165V, experienced a partial loss of engine power during a departure climb from the pilot's private airstrip near McClure, Ohio. The pilot subsequently performed a forced landing to a field about 100 ft north of departure end of the runway after the airplane was unable to maintain a positive climb rate. The private pilot and a passenger were uninjured and the airplane was substantially damaged on impact with terrain. The airplane was registered to and operated by the pilot under Title 14 Code of Federal Regulations Part 91 as a personal flight that was not operating on a flight plan. The local flight was originating at the time of the accident.

The pilot stated that after he performed a walk around inspection of the airplane and loaded the passenger and pushed the airplane outside. He started the airplane in front of hanger and allowed the engine to warm up to 120°F using an engine speed of 3,000 rpm. He taxied about 1,500 feet to the southern end of the north runway, where he performed an engine runup, checked both ignitions, and checked the flight controls. During the takeoff roll, the airplane lifted off the runway about 500 feet down the runway and climbed 50 - 100 ft above ground level at which point engine sound "backed off gradually." He ensured the throttle control was full forward and pumped the throttle control twice, but the engine speed continued to decrease. The pilot decided to perform an off-airport landing on a field which the airplane stuck a powerline pole and the right wing impacted the ground.

Following the accident, the pilot reported the engine, Rotax 582, had low cylinder compression and scoring on the piston and cylinder walls. There were also aluminum fragments within the cylinder. He said that the engine was overhauled about one year prior to his purchase of the airplane by the previous owner. He was "fairly certain" that the engine did not have any problems before the accident flight. The pilot installed a heater that used the engine's cooling system, and on the following flight after the installation, there was a differential exhaust gas temperature between two cylinders, one was high in temperature and the other cylinder was low in temperature. He said that the engine runup after the installation was normal.

The pilot stated a thermostat was installed on the coolant system and coolant was used for cabin heat. He said the engine radiator was not covered for cold weather operation. He felt the piston failure was due to cold seizure.

According to the Rotax 2-Stroke Maintenance Schedule, the Rotax 582 engine had a minimum coolant temperature of 150°F.

An Ultralight News article discussed cold seizures occurring in Rotax 532/582 engines by coolant having been cooling in the radiator, in winter in cold temperatures, which can mean that the temperature is down below 100°F. The engine on the other hand is under load and is creating heat, the pistons are expanding. As the cold liquid enters the area around the cylinders, the cylinder shrink and this causes a cold seizure.

The Federal Aviation Administration Aviation (FAA) Safety Inspector from the Cleveland Flight Standards District Office stated the pilot reported that an engine cylinder compression check was not performed when he purchased the airplane, and a cylinder compression check was not performed during the last condition inspection of the airplane. The engine was not examined by the FAA, and the engine manufacturer declined to attend an examination.