CEN23LA297

Loss of engine power for reasons that could not be determined.

The pilot stated that the preflight inspection and engine runup revealed no anomalies and the takeoff, climb, and initial portion of cruise were routine. He noted that the engine missed briefly about halfway through the flight. However, as the flight progressed, the engine sputtered briefly and then lost power completely, although the propeller continued to windmill. The pilot reported he cycled the ignition thinking that the issue might be ignition related since it had been recently serviced. He recalled that the engine stopped just after he turned off the left magneto and did not restart when it was switched back on. He added that the right magneto shut down briefly. He activated the fuel boost pump and switched fuel tanks but his efforts to restore engine power were not successful. The pilot activated the airframe parachute, and the airplane touched down in a corn field. Engine data recovered from the onboard avionics appeared stable throughout the flight until about 70 seconds before the accident. At that time, the engine fuel flow decreased to zero over a 26-second interval. The exhaust gas temperatures also began to decrease. Then, about 54 seconds before the accident, the engine speed began to decrease from 2,600 rpm until it reached 1,360 rpm. During the postaccident examination, no anomalies with respect to the airframe or engine fuel systems was observed and, according to recovery personnel, both fuel tanks contained useable fuel. The airplane was equipped with dual electronic ignition systems. The postaccident examination revealed that the fuse powering the right ignition controller module was open, which rendered the right ignition system inoperative. No preimpact anomalies were observed with respect to the left ignition system, nor any anomalies with respect to the fuel system or the engine assembly itself. The investigation was unable to determine exactly why the engine missed during the flight or why the fuse was tripped. One possibility is that the engine missed when the fuse tripped, and the right ignition system became inoperative. At that point, the engine continued to operate on the remaining ignition system. When the pilot cycled off the left ignition system to troubleshoot the cause of the engine miss, he inadvertently shut off the only remaining ignition system, resulting in a total loss of engine power. The pilot’s attempt to determine if the anomaly was ignition system related by isolating one system and then the other was reasonable. Because the ignition system fuses were installed behind the cockpit circuit breaker panel, the pilot was unable to detect the tripped fuse and determine that the right ignition system was inoperative. However, the engine should have been able to operate on the left ignition system. Ultimately, the reason for the loss of engine power could not be determined.

On July 11, 2023, at 2103 central daylight time, a Cirrus SR22 airplane, N151SR, was substantially damaged when it was involved in an accident near Boelus, Nebraska. The pilot was seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that the preflight inspection revealed no anomalies, and the engine runup “revealed nothing unusual after all checks [were] performed.” The takeoff and climb were routine, and he climbed to about 1,500 ft above ground level (agl) for the cruise portion of the flight. He noted that the engine missed briefly about halfway through the flight. As the flight progressed, just north of Boelus, the engine sputtered briefly and then lost power completely, although the propeller continued to windmill. The pilot reported that he “cycled the ignition as soon as the engine first missed,” thinking that the issue might be ignition related since it had been recently serviced. He recalled that “the engine stopped just after [he] cycled off magneto #1 [the left side magneto] and did not restart when it was switched back on.” He added that the right side magneto (#2) shut down briefly. He activated the fuel boost pump and changed fuel tanks. His efforts to restore engine power were not successful. The pilot initially set up for a forced landing to a gravel road; however, due to power lines and trees he decided to activate the airframe parachute system, and the airplane touched down in a corn field. According to ADS-B data, the pilot departed Werner Ranch Airfield (NE36), Anselmo, Nebraska, at 2034. He proceeded southeast on a direct course toward Central Nebraska Regional Airport (GRI), Grand Island, Nebraska, at an en route cruise altitude of about 3,200 ft mean sea level (msl). About 2102:07, the airplane entered a gradual descent which continued until the end of the ADS-B data. Almost one minute after entering the descent, the airplane began a right turn to a southerly course. The final ADS-B data point was recorded at 2103:14 with an associated altitude of about 2,045 ft msl. The accident site was located about 112 ft south of the final data point at an elevation about 2,026 ft. Data recovered from the onboard avionics depicted stable engine operation throughout the flight until about 2101:40. At that time, the engine fuel flow decreased from 15.6 gallons per hour (gph) to 12.7 gph before increasing to 13.7 gph at 2102:56. Afterward, the fuel flow decreased abruptly and ultimately went to zero. Also about 2101:40, the engine exhaust gas temperatures began to decrease. About 2101:56, the engine speed began to decrease from 2,600 rpm until it reached 1,360 rpm at 2102:50, the end of the recorded data set. Postaccident examinations of the airframe fuel system and engine did not reveal any anomalies that would have resulted in a loss of engine power. The airplane was equipped with dual electronic ignition systems. The left ignition coil unit was damaged consistent with impact. Testing of the unit was limited due to the damage, but no anomalies were observed. The right ignition coil was damaged consistent with impact and could not be tested. Testing of the remaining ignition system components did not reveal any anomalies. The ignition system was protected by in-line fuses installed behind the cockpit circuit breaker panel. They could not be inspected without opening the panel. One ignition system was connected to the main electrical bus, and the second ignition system was connected to the essential electrical bus at the cockpit circuit breaker panel. The ignition coils were each protected by 10-amp, in-line fuses. The ignition controller modules were each protected by 2-amp, in-line fuses. Both10-amp fuses were intact. The 2-amp fuse corresponding to the left ignition controller unit was intact. The 2-amp fuse corresponding to the right ignition controller unit was open and not operational at the time of the postaccident examination; no filament was observed. Electrical continuity of the ignition power wiring from the electrical bus to the ignition coil units and to the ignition timing units was confirmed. A review of the airplane maintenance records revealed that the electronic ignition systems were installed in January 2015 and August 2022. Based on the component serial numbers, the left system was installed in 2015 and the right in 2022. Maintenance records indicated that, on December 15, 2022, a “mag pickup EA-10000MTH” was removed and sent to the manufacturer for compliance with a service bulletin. The same component was re-installed after the service bulletin repair. The spark plugs were replaced on April 20, 2023, because they were “intermittently arcing to [the] plug case,” causing false lightning strike targets on the Storm Scope. The ignition system timing was checked on May 23, 2023, and no defects were noted. The maintenance records provided contained no entries following the May 23rd entry. The flight manual supplement specified no revisions to emergency procedures. The supplement noted a maximum engine speed drop during the before-takeoff ignition system check of 40 rpm. The airplane flight manual noted that in the case of a partial loss of engine power, “cycling the ignition switch momentarily from BOTH to L[eft] and then to R[ight] may help identify the problem. An obvious power loss in single ignition operation indicated magneto or spark plug trouble.”