Malfunctions were detected in the flight control system and engines of the aircraft, the sources told RNS news agency. They added that the malfunctions were "not critical" and had no impact on the course of the campaign.
Specialists from the Sukhoi Design Bureau as well as two Russian aircraft manufacturer were at the Hmeymim airbase, the centerpiece of the military campaign.
The sources said that maintenance and details replacement were carried out at the base. All glitches were minor and fixed within a very short time.
Last October, Strategy Page reported that the Russian military faced difficulties with maintaining its modern warplanes in the sand and dust of the Middle East. Russian maintenance crews worked overtime to adapt the aircraft involved in the operation to the environment.
The Su-34 is Russia’s most advanced interdiction aircraft. It made its combat debut over Syria recently. It is armed with R-73 dogfighting missiles and R-77 long-range radar-guided air-to-air missiles. The aircraft has a combat radius of nearly 700 miles on internal fuel but is also capable of aerial refueling.
The Su-35 fighter jet is an upgraded version of the Su-27 multirole fighter. It was first introduced to a foreign audience at the 2013 Paris Air Show.