CEN23LA273

A partial loss of engine power during the test flight due to multiple ignition system anomalies.

According to the pilot, the accident occurred during his first flight of the experimental airplane. About 8 minutes after takeoff, upon reaching an altitude of about 3,250 ft mean sea level (msl), the airplane entered a gradual descent, and the pilot realized that the engine had lost partial power. He decided to return to the airport. He recalled the fuel pressure, fuel flow, and manifold pressure were within normal limits at that time. However, when the pilot activated the fuel boost pump, the engine lost all power. The airplane did not have sufficient altitude to reach the airport, and the pilot executed a forced landing to a road. The airplane impacted a sign and trees adjacent to the road before coming to rest in a residential driveway. The pilot noted that when the airplane came to rest, he heard a “fast humming” sound and immediately switched off the ignition. Both wings separated from the fuselage, and both canards were damaged. Each of the four propeller blades were separated at the blade roots and fragmented. A postaccident engine examination revealed several anomalies. The ignition harness leads corresponding to the Nos. 3 and 4 cylinder upper spark plugs were disconnected from the ignition module. In addition, the Nos. 1, 2, and 6 upper, and the No. 2 lower spark plug leads were loose and not fully connected at the ignition module. The ignition modules were tested and operated normally. The Nos. 1 and 2 cylinder spark plugs exhibited normal operating signatures; however, the remaining spark plugs exhibited sooty deposits. Engine data retained by the onboard avionics revealed the engine speed remained stable until about 6 minutes after takeoff when it decreased about 200 rpm consistent with a partial loss of engine power. At that time, the No. 1 cylinder head temperature (CHT) and exhaust gas temperature (EGT) decreased dramatically. The No. 2 CHT and EGT remained low for most of the flight. About 14 minutes after takeoff, the engine speed decreased further from approximately 2,500 rpm to about 1,200 rpm with corresponding decreases in the other engine parameters. Approximately 15 seconds after the reduction in engine power, the fuel pressure increased consistent with the pilot activating the electric fuel boost pump. About one minute after the reduction in engine power, the pilot touched down on the road during the forced landing, and six seconds later the engine speed and fuel flow increased abruptly and momentarily and then abruptly dropped to zero. The sudden increase in engine speed after impact suggested the engine had not lost power completely, and the engine speed increased when the propeller blades fractured during the accident sequence, which removed the resistive torque from the engine. The partial loss of engine power was likely due to the ignition system anomalies observed during the postrecovery examination.

On July 1, 2023, about 0853 central daylight time, a Berkut 540 airplane, N567JS, was substantially damaged when it was involved in an accident near Cedar Rapids, Iowa. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight. The pilot reported this was his first flight of the experimental airplane. After takeoff, the pilot proceeded east of the airport and was cleared to 5,000 ft msl. However, upon reaching 3,400 ft msl, the airplane entered a gradual descent, and the pilot realized that the engine had lost partial power. He decided to return to the airport. Fuel pressure, fuel flow, and manifold pressure were within normal limits at that time. When the pilot activated the fuel boost pump as the airplane neared the airport, the engine lost power completely. Unable to reach the runway, the pilot executed a forced landing to a road. The airplane touched down safely, but as it neared an intersection, the airplane encountered a surface bump causing it to veer to the left. The airplane impacted a sign and trees adjacent to the road before coming to rest in a residential driveway. The pilot noted that when the airplane came to rest, he heard a “fast humming” sound and immediately switched off the ignition. Both wings separated from the fuselage, and both canards were damaged. Each of the four propeller blades were separated at the blade roots and fragmented. ADS-B and onboard avionics data revealed that the flight departed at 0839 from runway 27 at The Eastern Iowa Airport (CID), Cedar Rapids, Iowa. The pilot proceeded about 4.25 miles southwest before turning to the east. About 0847, the airplane was about 7 miles east of the airport and at an altitude of about 3,250 ft msl. About this time, the airplane entered a gradual descent. The airplane continued eastbound until about 11 miles from the airport when the pilot reversed to a westbound course. About 0853:20, the airplane appeared to be on a west-northwest course, about 3.25 miles east of the airport and at an altitude about 1,350 ft msl. About that time, the airplane entered a gradual turn toward the north which continued until the end of the data. The final ADS-B data point was recorded at 0853:49 with a corresponding altitude of about 875 ft msl (about 60 ft above ground level). The airplane was located about 0.20 miles south of the accident site at that time. The onboard avionics continued recording after the final ADS-B data point. According to that data, at 0853:53, the airplane reached the road, and the altitude data remain stable consistent with the airplane touching down on the road during the forced landing. The airplane subsequently came to rest upright in the residential driveway about 0853:59. The left and right wings were separated during the impact sequence. The left canard was damaged, and the left landing gear collapsed. Each of the four propeller blades were separated near the hub. The elevation at the accident site was about 772 ft. A postrecovery engine examination conducted by FAA inspectors revealed several anomalies. The ignition harness leads corresponding to the Nos. 3 and. 4 cylinder upper spark plugs were disconnected from the ignition module. In addition, the Nos. 1, 2, and 6 upper, and No. 2 lower spark plug leads were loose and not fully connected to the ignition module. The ignition modules were tested and operated normally. The Nos. 1 and. 2 cylinder spark plugs exhibited normal operating signatures; however, the remaining spark plugs exhibited sooty deposits. The electric fuel boost pump was inoperative at the time of the examination due to tripped circuit protection. When the circuit was reset, operation of the fuel pump again tripped the circuit protection. Engine data retained by the onboard avionics revealed that exhaust gas temperatures (EGT) trended near 1,200°F until about 0852, with three 3 exceptions. The No. 1 cylinder trended near 1,200°F until about 0845 when it decreased to 560°F until 0852. The EGT for cylinder No. 2 trended near 590°F until about 0852. The pilot stated that the EGT for cylinder No. 6 was not configured, and the resulting data was not reliable. The CHT trended in the 350°F to 450°F range with 2 exceptions. The No. 1 cylinder CHT trended with the other cylinders until about 0845:00, when it decreased from about 415°F to about 165°F. The No. 2 cylinder CHT started at 290°F but immediately decreased to about 175°F and remained there for the duration of the flight. The engine speed was about 2,650 rpm until about 0845:00 when it decreased to 2,450 rpm. Then, about 0852:45, the engine speed decreased from about 2,500 rpm to roughly 1,200 rpm. The oil pressure, fuel flow, EGT, and CHT also decreased at that time. The fuel pressure increased at 0853:00 consistent with the pilot activating the electric fuel boost pump. About 0853:58, the engine speed and fuel flow increased abruptly and momentarily. However, a few seconds later, both parameters dropped to zero. Similarly, the EGT increased abruptly and then decreased gradually through the end of the data set.