Aeroflot's first 10 Sukhoi Superjets are all under a temporary contract which will involve replacing the aircraft with upgraded versions.
The Russian flag-carrier has 30 of the type on order but the first 10 have been handed over.
Sukhoi's civil aircraft division confirms that it agreed with Aeroflot that the first 10 of the 30 would be delivered in a "light" configuration - not conforming to the original specifications of the carrier.
"A number of changes requested by Aeroflot have needed additional study," says the airframer, adding that these involve changes to the layout, avionics and fittings.
It says the first 10 aircraft ordered are being delivered to the "light" specification and that these will be replaced by Superjets meeting the full requirement of the airline.
Aeroflot requested the configuration changes after signing the order in 2005, Sukhoi adds.
Sukhoi says the initial Aeroflot aircraft, once returned, can be acquired by customers interested in taking the type second-hand.