ERA22LA268

Shortly after takeoff while on a local flight, the pilot, who was also the owner of the airplane, heard and felt an unusual vibration emanating from the engine. The pilot elected to return to the private airfield as the experimental automobile engine was still running. He declared an emergency as the engine was losing coolant, and the coolant and oil temperature steadily rose to very high levels. Fearing a complete engine failure, he elected to fly straight in and land on an un-mowed portion of the airport. As the airplane touched down the nose gear collapsed, causing the airplane to impact the terrain and come to a sudden stop that resulted in substantial damage to the airframe. The pilot, who was also an aircraft mechanic, examined the engine and discovered that the engine gearbox drive flange, also known as a “spider,” had failed. The three-eared flange had fractured outside of the splined driveshaft hole. The resulting failure threw parts into the radiator, puncturing it. The punctured radiator lost coolant, causing a subsequent engine over-temperature that likely would have led to a complete loss of engine power. Fearing an imminent loss of engine power, the pilot made a precautionary landing on an unimproved part of the airport.

On May 9, 2022, about 1015 eastern daylight time, an experimental, amateur-built Escapade airplane, N86RD, was substantially damaged when it was involved in an accident at a private airport in Brasstown, North Carolina. The commercial pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, who was also the owner of the airplane, shortly after departure from the private airport, the engine developed vibrations and an “unusual sound.” He attempted to return to the airport, which was about 8 nautical miles away. Although the engine was developing power, the engine was losing coolant and the coolant and oil temperatures were rising to excessive levels. In lieu of flying an airport traffic pattern, which would take additional time, he elected to land as soon as possible on an un-mowed portion of the airport. The nose gear collapsed during the landing, which resulted in damage to the fuselage and windscreen. The wreckage was subsequently recovered and examined by a Federal Aviation Administration (FAA) inspector. The inspector noted substantial damage to the airframe. The accident, which was reported about a month after it occurred, and the subsequent follow-up examination by the FAA, took additional time before the damage was confirmed; during which time the pilot, who was also an airframe and powerplant mechanic conducted his own examination. The pilot stated that during his examination of the experimental Viking 110 engine (Honda Derivative), it was revealed that the drive flange, also known as the engine to gearbox coupling or “spider,” located on the rear of the gearbox, had failed (Figure 1). The resulting failure threw fragments into the radiator, damaging it and resulting in coolant loss. The pilot removed the flange, which was missing one of the three drive ears. One of the ears was fractured just outside of the main splined driveshaft hole. Figure 1 Fractured flange prior to removal. The flange was installed on the engine about 134 flight hours before the accident and was accomplished by the previous owner of the airplane. A review of the engine manufacturer’s operational manuals and service bulletins revealed that this unit was in compliance with the service bulletin specific to the welding of the pins and installation.