Russian authorities are not intending to restrict Antonov An-148 operations following the in-flight upset to a Rossiya aircraft en route to St Petersburg earlier this month.

After departing Moscow Vnukovo on 4 June the twin-jet was cruising at 10,600m (34,800ft), with 54 passengers and five crew members on board, when the upset occurred.

Preliminary information indicates that the aircraft, conducting a night flight, suffered an uncommanded rudder deflection, and entered a steep right bank - some 56° - and pitched downwards before the crew brought the jet under control.

Federal air transport agency Rosaviatsia confirms that the aircraft banked and lost height but states: "The crew promptly switched to manual control, then made a safe landing at St Petersburg Airport."

Investigators from Russia's Interstate Aviation Committee (MAK) states that the fault was linked to a malfunctioning control system.

Inquiries discovered damaged insulation on an electrical cable which appears to have resulted in the transmission of spurious signals.

MAK says that an airworthiness directive has already been issued aimed at verifying the integrity of the supply chain for An-148 production.

Design bureau Antonov, Voronezh-based airframer VASO, and systems developer Moscow Institute of Electromechanics and Automation are participating in the investigation.

But Rosaviatsia says that there is "no reason" to restrict the flights of the An-148, three of which are among the Rossiya fleet - including the airframe involved in the incident, RA-61701.

It adds that any problems arising with the type, particularly at this early stage of its introduction to airline service, would be carefully assessed in order to implement solutions to ensure continued safe operation.

Source: Air Transport Intelligence news