Accident Details
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 feet north of the 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 sustained substantial damage on impact with terrain. The flight was personal under Title 14 Code of Federal Regulations Part 91 and was not operating on a flight plan. The local flight was originating at the time of the accident.
Pilot's Account
The pilot reported that after performing a walk-around inspection and loading the passenger, he started the engine in front of the hangar and allowed it to warm up to 120°F using an engine speed of 3,000 rpm. He then 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 feet above ground level, at which point the engine sound "backed off gradually." The pilot ensured the throttle control was full forward and pumped the throttle twice, but the engine speed continued to decrease. He decided to perform an off-airport landing on a field, where the airplane struck a powerline pole and the right wing impacted the ground.
Engine Issues
Following the accident, the pilot reported that the engine, a Rotax 582, had low cylinder compression and scoring on the piston and cylinder walls, with aluminum fragments within the cylinder. He stated that the engine had been overhauled about one year prior to his purchase of the airplane by the previous owner and that he was "fairly certain" the engine did not have any problems before the accident flight. The pilot had installed a heater that used the engine's cooling system, and on the first flight after installation, there was a differential exhaust gas temperature between two cylinders—one high and one low. He said the engine runup after the installation was normal.
The pilot stated that a thermostat was installed on the coolant system and that coolant was used for cabin heat, but the engine radiator was not covered for cold weather operation. He felt the piston failure was due to cold seizure.
Maintenance and Manufacturer Information
According to the Rotax 2-Stroke Maintenance Schedule, the Rotax 582 engine has a minimum coolant temperature of 150°F. An Ultralight News article discussed cold seizures occurring in Rotax 532/582 engines when coolant in the radiator is cooled in cold temperatures, potentially below 100°F. Under load, the engine creates heat and pistons expand; as cold liquid enters the area around the cylinders, the cylinders shrink, causing a cold seizure.
The Federal Aviation Administration (FAA) Safety Inspector from the Cleveland Flight Standards District Office stated that the pilot reported an engine cylinder compression check was not performed when he purchased the airplane, nor during the last condition inspection. The engine was not examined by the FAA, and the engine manufacturer declined to attend an examination.