MOSCOW (AP) — Russian aviation experts ran into technical problems Friday as they began examining the flight data recorders from a plane crash that killed 43 people.

Investigators have not yet been able to pinpoint what caused the chartered Yak-42 jet to crash Wednesday into the banks of the Volga River shortly after takeoff from an airport near Yaroslavl, 150 miles (240 kilometers) northeast of Moscow.

The magnetic tapes holding the flight information in the data recorders were still wet and investigators can’t begin deciphering them until after they dry out, the Interstate Aviation Committee said on its website Friday.

Aviation authorities are now running checks on all the approximately 60 Yak-42 jets currently in service in Russia.

The crash killed 43 people, including 36 players, coaches and staff of the Lokomotiv Yaroslavl ice hockey team, many of whom were European national team and former NHL players. It was one of the worst aviation disasters ever in sports, shocking Russia and the world of hockey.

The team had been heading to Minsk, Belarus to play its opening game of the Kontinental Hockey League season.

The two crash survivors — player Alexander Galimov and crew member Alexander Sizov — were still in critical condition Friday after being transferred to Moscow for treatment. Hospital officials said Galimov has suffered burns to 90 percent of his body and has been placed in a medicated coma to help ease the healing process.