Accident Overview
On April 22, 2021, at approximately 1004 mountain daylight time, a Flight Design GMBH CSTW light sport airplane, registration N378CT, was substantially damaged during an accident near Santa Fe, New Mexico. The airplane was operating as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor reported no injuries, while the pilot receiving instruction sustained a minor injury.
Flight Sequence
The flight instructor stated that while returning to the departure airport at an altitude of about 7,500 ft mean sea level, he noticed a decrease in oil pressure. All other engine indications appeared normal. He climbed to a higher altitude to monitor the oil pressure and positioned the airplane over a suitable landing area. The oil pressure continued to decrease, and when it reached approximately 4 psi, the engine abruptly stopped. The flight instructor executed a forced landing on a dirt field about 8 miles south of the airport. During the ground roll, the nose wheel struck a rock, causing the airplane to nose over. The instructor added that during the preflight inspection, the oil level was correct and no oil leak was observed.
Oil Pressure Data
A review of data from the Dynon EMS-D120 device indicated that the oil pressure decreased steadily over the last 25 minutes of flight. Approximately 3 minutes before the off-field landing, the oil pressure rapidly dropped to zero, and shortly thereafter, the engine rpm decreased to zero.
Postaccident Examination
Postaccident examination revealed that the oil supply line from the oil tank to the oil pump, which supplied the engine, leaked when compressed air was introduced into the line. The leak was located in the area where the oil line rested against the exhaust manifold. The damage to the oil line was consistent with exposure to heat from the exhaust manifold. The oil line was connected correctly but was routed too close to the exhaust manifold.