US investigators have been unable to determine the reason for a MHIRJ CRJ200’s veering to the right upon landing, resulting in a runway excursion at Dayton.
But the inquiry says a “reliance primarily on differential braking” rather than opposite rudder, as the pilot attempted to arrest the turn, contributed to the incident.
The Air Wisconsin aircraft, arriving from Washington Dulles in daylight and good weather on 5 October 2022, had touched down on runway 24L at 127kt.
Its spoilers activated, wheel braking started to increase on both main landing-gear, and both thrust-reversers were deployed – the left for 6s and the right for 4s.
After engaging reverse thrust, the captain maintained the runway centreline for about 9s. But about 1-2s before the reversers started to stow, at a groundspeed of 97kt, the aircraft began veering to the right.
According to the National Transportation Safety Board, the crew made two “brief” left-rudder inputs, followed by differential braking towards the left.
But these actions “did not counteract” the aircraft’s tendency to turn to the right, the inquiry adds.
The first officer also started braking but the crew could not prevent the jet’s leaving the runway about 12s after nose-wheel touchdown.
It travelled over grass and came to a halt on a parallel taxiway. The aircraft sustained minor impact damage to its left wing-tip and puncture on the left wing’s leading edge.
While there had been a crosswind component present, about 3kt from the right, the inquiry says this would have been “negligible”.
The thrust-reverser use had been asymmetric, with right-engine power peaking higher than left, but this was “brief” and “not unusual”, it states, and “unlikely to cause a continuous right turn”.
Three previous landings that involving the aircraft, the inquiry points out, showed power asymmetries of 5-15% during reverse thrust, favouring the right engine, without loss of directional control.
It concludes that the right turn developed during the landing roll “for reasons that could not be determined based on the available evidence”. None of the 42 passengers and three crew members was injured.
