Russian carrier Rossiya is seeking special checks on Antonov An-148 aircraft after one of those in its fleet suffered an in-flight upset traced to an uncommanded rudder deflection.
Rossiya says the aircraft, registered RA-61701, experienced the deflection in cruise while en route from Moscow to St Petersburg on 4 June.
The rudder deflected 3.5° to the right over the course of 2s while the rudder pedals remained static, says the carrier which conducted an in-house investigation into the incident.
Rossiya adds that the event took place at an altitude of 10,600m (34,800ft) while the jet was travelling at 472km/h (255kt) with the autopilot engaged.
"As a result, the aircraft began skidding in a gliding turn and receiving a very substantial lateral g-load," it says.
The erratic behaviour of the aircraft continued, culminated in its banking to the right by 56° and pitching down by 26°, and the jet was subjected to a heavy - although not excessive - load as the crew recovered from the dive, states a preliminary set of findings into the incident.
"During the rest of the flight the crew piloted the aircraft manually with the automatic thrust control on," says Rossiya.
A technical inspection conducted by Rossiya's flight safety division detected a 5-7mm lengthwise cut in part of the cabling insulation. This damage resulted in electrical signal disruption, affecting the flight-control stability.
Rossiya has requested that airframer VASO, which manufactures the An-148, to carry out specific quality checks on the type's electrical wiring.