MiG-23 crashed at Thunder Over Michigan after partial engine power loss

The National Transportation Safety Board has released its final report into the crash on August 13, 2023, of a privately owned MiG-23UB during Thunder Over Michigan at Willow Run Airport (YIP).  

The jet was the MiG-23UB registered N23UB, a two-seat trainer built in 1981, flying in the United States under a special Experimental Airworthiness Certificate for air show exhibition. Powered by a single Tumansky R27F2M-300 afterburning turbojet rated at 23,000 pounds of thrust (around 102 kilonewtons), the airframe had logged 1,697 hours at its most recent AAIP inspection on July 17, 2023, with five hours since that check. 

Investigators concluded the jet suffered a partial loss of engine power for reasons that could not be determined. Both pilots ejected at low altitude and were seriously injured. There were no injuries on the ground. 

A low ejection with little margin 

The display profile called for a sweeping “banana pass”. As the front-seat pilot advanced the throttle for afterburner, the Tumansky R27F2M-300 did not respond. Attempts to re-select the afterburner brought no change. With energy bleeding away, the crew turned back toward the airport, trading height for speed and managing the angle of attack to avoid a stall. However, the available thrust was not enough to keep the MiG-23 flying. 

The rear-seat pilot announced an emergency and configured the aircraft for slower flight, selecting a 16-degree wing sweep and later deploying takeoff flaps as the speed dropped below 200 knots (approximately 370 kilometers per hour). When it became clear that the projected path would leave airport property, he initiated ejection at about 350 feet (around 107 meters).  

A video of the incident shows both parachutes opening just above the treetops before the pilots come down in a nearby lake. The aircraft struck a residential area about 1.7 miles (around 2.7 kilometers) south of runway 27. The wreckage trail measured about 600 feet (around 183 meters), and the fuselage with the engine came to rest beside an apartment building. 

Video of plane crashing at the Thunder Over Michigan Air Show and pilots parachuting. Hoping everyone is ok. #thunderovermichigan pic.twitter.com/RtAAjw7OVV— Danny Phillips (@DannyPhillips46) August 13, 2023

The seats installed in this MiG-23 were not zero-zero capable, meaning that they were not designed for use from ground level at zero airspeed. The flight manual links minimum safe ejection height during a descent to the rate of descent, using a simple rule of five times the vertical speed. At 350 feet (around 107 meters), that only covers a 70 feet per minute descent, about 0.36 meters per second, and the actual sink rate was likely higher. Investigators judged the timing to be appropriate, noting that an earlier decision could have reduced injuries, while any delay would have increased the risk.  

The manual allows ejections in level flight up to 270 knots (around 500 kilometers per hour) without height limits, requires at least 100 feet (around 30 meters) above ground between 500 and 620 knots (around 926 to 1,148 kilometers per hour), and at least 3,300 feet (around 1,006 meters) between 620 and 650 knots (around 1,148 to 1,204 kilometers per hour). 

What the wreckage showed 

Photographs and on-scene evidence pointed to an engine that was still rotating under some power at impact. Fan blades showed hard-body strikes and multiple tip fractures around the circumference, with scoring on the spinner. The traces were consistent with residual thrust, although investigators could not quantify exactly how much. 

The Tumansky R27F2M-300 is a Soviet-designed turbojet, and there is no independent facility in the United States with the specialized tooling and experience to perform a full teardown. Without that work, the investigation relied on statements, photographs and maintenance records. That limitation prevented the NTSB from isolating a single failure mode behind the loss of thrust. 

The people and the machine 

The aircraft involved in the accident, MiG-23UB N23UB, was built in 1981 and operated under an Experimental certificate for air show exhibition. The pilot in command reported about 21,296 total hours, including 42 hours on type, and is a former US Naval aviator. The rear-seat pilot, a lieutenant colonel in the US Air National Guard, reported about 15,000 hours, including 12 hours on type.  

Weather conditions were visual, with 10 miles (around 16 kilometers) visibility, wind from 330 degrees at 10 knots (around 19 kilometers per hour), and a temperature of 27 degrees Celsius. Willow Run is situated at an elevation of 715 feet (approximately 218 meters), with runway 5/23 measuring 7,543 feet (approximately 2,300 meters) and runway 9/27 measuring 5,001 feet (approximately 1,524 meters). 

Investigators noted a prior power-loss event on the same airframe in 2018. Maintenance at the time identified a leaking fuel control unit, which was replaced. In his current statement, the pilot suggested the accident sequence might instead relate to the exhaust nozzle actuation system, but without a teardown, the NTSB could not verify that hypothesis. 

The NTSB’s conclusions 

Low-level display profiles offer limited opportunities to recover energy when thrust is unavailable, especially in aircraft equipped with seats that lack zero-zero capability. The NTSB’s findings emphasize the importance of making prompt decisions regarding ejection in these situations.  

Additionally, the report highlights the challenges faced by privately-owned legacy jets. When there is a lack of resources for overhaul and teardown, both maintenance and accident investigations can be hindered, resulting in some causes remaining unresolved. The post MiG-23 crashed at Thunder Over Michigan after partial engine power loss appeared first on AeroTime.

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