CEN23FA361

A reported partial loss of engine power while maneuvering for reasons that could not be determined.

Both the front-seat pilot-in-command (PIC) and the rear-seat pilot-rated observer (PRO) of the Russian-manufactured fighter jet reported that the airplane’s engine did not respond to application of afterburner power during a display pass at an air show. According to the PIC, the engine was operating in a degraded power condition that was insufficient to sustain altitude and airspeed. The PIC maneuvered the airplane back toward the airport while he attempted to restore engine power. The PIC believed that his corrective measures would have restored engine power; however, the PRO activated the crew ejection system before engine power was restored. The PRO reported that he inquired about ejection with the PIC but did not hear a response before he activated the ejection system; however, the PIC reported that he replied “no” in response to the PRO’s ejection inquiry and that he was ejected from the airplane while he was troubleshooting the loss of engine power and still flying the airplane. Although the PIC was completing corrective actions, engine power was not restored by the time of the crew ejection and, therefore, the investigation was unable to determine if his corrective efforts would have been successful. According to the PRO, the ejection system was activated about 350 ft above ground level (agl) and below 200 kts. Both pilots were ejected from the airplane, with the PRO ejected first, followed by the PIC. The airplane continued in a left bank and descended into the ground about 1.7 miles from the runway. The airplane impacted the ground adjacent an apartment building and was destroyed by impact forces and a post impact fire. Other than the PIC’s mechanic, the NTSB was unaware of any independent engine shop or manufacturer within the United States with the appropriate tooling and expertise to perform a teardown examination of the Tumansky R27F2M-300 engine. The PIC’s written statement addressed potential sources for degraded engine performance; however, the NTSB could not validate the PIC’s opinion of the reason for the loss of engine power. Based on photographic evidence, the engine was producing some power at impact; however, the level of power output could not be determined. Due to investigative support limitations and the extend of damage, the investigators were unable to determine the reason for the loss of engine power. The airplane flight manual indicated that during a descent, the minimum safe altitude for crew ejection is calculated based on the airplane’s rate of descent and is equal to the rate of descent multiplied by 5. Based on the 350 ft agl altitude at ejection provided by the PRO, this altitude would be appropriate for ejection at a maximum rate of descent of 70 feet per minute (fpm). Although the airplane’s actual rate of descent was not known, it was likely significantly higher than the 70 fpm limitation at the time of crew ejection. Additionally, video evidence showed that the ejection seat parachutes did not fully deploy until the occupants had descended to just above treetop level. Therefore, the timing of the crew ejection was not premature. Given the serious injuries received by both occupants, crew ejection at a higher altitude may have reduced the severity of their injuries. Likewise, had the crew ejection been further delayed, the occupant injuries may have been more severe.

The PIC, who was the owner of the airplane, held an airline transport pilot certificate with type ratings for Airbus 320, Boeing 757, Boing 767, Boeing 777, Aero Vodochody L39, and MiG 23 airplanes. He reported having a total of 21,296 hours of total flight experience, including 42 hours in MiG 23 airplanes. In addition to his civilian flight experience, the pilot previously served as a United States Naval Aviator. During his military career, he accumulated 2,500 hours flight experience, including 47 combat missions, and 250 aircraft carrier landings. The rear-seat PRO held an airline transport pilot certificate with type ratings for Boeing 777, Airbus 320, McDonnell Douglas DC-9, Bombardier Canadair Regional Jet CL-65, Saab 340, Embraer 500, Embraer 505, SIAI-Marchetti S.211, and Aero Vodochody L-39 airplanes. He reported having a total of 15,000 hours of flight experience, including 12 hours in MiG 23 airplanes. He was an active Lieutenant Colonel in the Air National Guard. He reported having over 2,400 hours of military jet flight experience, including 50 combat missions. He also reported having formal training on ACES 11 (F-16), Northrop Seat (T-38), and Martin Baker Mk 16 (T-6A) ejection seats. On August 13, 2023, about 1610 eastern daylight time, a Mikoyan Gurevich MiG-23UB airplane, N23UB, was destroyed when it was involved in an accident near Belleville, Michigan. The pilot-in-command (PIC) and pilot-rated observer (PRO) received serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 air show exhibition flight. The flight was performing at the Thunder Over Michigan Air Show held at the Willow Run Airport (YIP), Ypsilanti, Michigan. The accident flight was scheduled to be the second to last act. The airplane was a privately-owned, Russian-designed military fighter that employed variable geometry wings that allowed the wing sweep angle to be changed in flight. The airplane was powered by a single turbojet engine with an afterburner. The PIC was seated in the front cockpit and the PRO was seated in the rear cockpit. The PIC reported that the flight departed from runway 23 at YIP, first using maximum power, followed by minimum afterburner, and then maximum afterburner. He then deselected afterburner as he turned the airplane onto the downwind leg of the traffic pattern. The PIC noted nothing unusual at this time. The PIC then maneuvered the airplane for a “banana pass” (a low-level, knife-edge display pass) along runway 23. As the airplane approached for the display pass, the PRO swept the wings to the 45° position, at which time the PIC glanced at his airspeed indicator and noticed the airplane was slower than he thought it should have been, but it was still above the minimum maneuvering speed. The PIC believed this may have been the first indication that the engine was losing power, but he did not realize it at this time. To increase airspeed, he advanced the throttle and decreased pitch slightly. About this time, the PRO announced that it was time to engage the afterburner for the display pass. The PIC advanced the throttle to the full position and pulled the afterburner paddle switch to engage the afterburner, but there was no increase in engine power. He announced to the PRO that the afterburner did not engage and that he was attempting it again. He pulled the throttle back to midrange and then readvanced it, using the same procedure to engage the afterburner, but there was still no increase in engine power. The PIC and the PRO confirmed with each other that an emergency existed. The PIC visually located YIP and decided that he needed to continue toward the airport. About this time, the PRO announced that he had selected the wings to the 16° sweep position, which the PIC acknowledged. The PIC maneuvered the airplane back toward YIP using the angle-of-attack indicator to keep the airplane from entering an aerodynamic stall. He stated that his intention was to place the airplane into an area away from the public, at just above stall speed. The PIC located an area that met these criteria and was maneuvering the airplane toward that location. He also noted that the engine was running above idle and was still producing some thrust, but not enough to maintain airspeed and altitude. The PIC believed that the airplane would have been able to descend to a large field, just past a large highway but short of the runway. About this time, the PRO stated that flap deployment was needed, which the PIC delayed to maintain a better glide ratio. He believed he later selected the takeoff flap position when the airplane was about 190 kts, which was the lowest airspeed he remembered. The PIC stated that the flight controls were operating during the entire flight and that the airplane never approached an aerodynamic stall. The PIC stated that once the airplane was established in the glide to the selected landing area, he then had time to attempt to diagnose the loss of engine power. He first activated the emergency nozzle control but did not feel any immediate response from the engine. About that time, that the PRO stated, “We need to get out of the jet,” to which the PIC responded, “No.” The PIC stated he was surprised by the PRO’s statement, as he had not considered ejecting and did not thereafter. After attempting to reestablish engine power using the emergency nozzle control, the PIC intended to use the emergency engine control, which bypasses the automatic fuel control, to reestablish engine power; however, he did not remember if he was able to activate the switch before the ejection seat fired and he departed the cockpit. The PRO stated that while the airplane was descending and accelerating for a display pass, he swept the wings back to 45°. As they approached the air show line and the PIC moved the throttle forward into the afterburner range, the thrust from the engine dropped to near zero and the airplane began to decelerate. The PRO stated that the deceleration was such that he was pulled forward against his shoulder straps. The descent reached 500 ft agl, and the PIC began a climbing left turn. The PIC said that they had a problem, and the PRO agreed. The PIC moved the throttle to idle, then forward to the maximum without afterburner, and then into the afterburner range. The PRO stated that there was no change in engine rpm, no restoration of thrust, and no change in engine noise. The PRO stated that the PIC attempted this throttle movement at least three more times. As the airplane climbed, the airspeed decayed, and the PRO stated that he made airspeed callouts as the airplane slowed. The PRO told the pilot, “We need the wings to 16°,” and the PIC agreed. The PRO selected the 16° wing position, and the wings moved to that position. The PRO said that the airspeed decreased below 200 kts and he declared an emergency over the air show communication frequency. The PRO said they briefly discussed the engine power loss, and the PIC asked if they could make it to runway 27, to which the PRO replied, “No.” He said that the altitude peaked at 900 ft agl, and the PIC then began trading altitude to maintain airspeed. He said the airplane was in and out of the stall buffet, and he asked the PIC if they needed flaps. He stated that the PIC said, “Yes,” the PIC selected takeoff flaps, and the PRO confirmed the flap and slat deployment. The PRO stated that the airplane was in a descending left turn and the trajectory would intersect terrain outside the airport perimeter and over 2 miles south of runway 27 at YIP. He stated that he communicated the need to eject with the PIC. After several seconds without a response, as the airplane was descending below 350 ft agl, the PRO activated the ejection sequence and both occupants were ejected from the airplane. Video evidence indicated that the airplane was in a left bank when the ejection seats fired. The airplane continued in the left ban