Sukhoi has released video images of the first two Superjet 100 flight-test aircraft, showing the two airframes in formation flight.
The images of aircraft 95001 and 95003 have emerged as the Superjet's engine supplier, Franco-Russian venture PowerJet, hints at broad economic pressures on the programme.
PowerJet is due to deliver SaM146 engines for the third test aircraft in March-April, and stresses that the powerplant assembly line is not causing any hold-up.
But it adds: "Realisation of such a large-scale, international high-tech programme, in the context of the global financial crisis, will inevitably face new challenges."
PowerJet says the project will require "open and honest" partnership by all participants in order to recognise and address problems. It does not mention any specific concerns, and points out that its own engine production is in line with the development schedule.
The fourth Superjet is due to receive its engines in June-July, the company adds.
Sukhoi's first two aircraft have logged more than 80 flights and the engines have accumulated around 2,300hr in flight and ground tests. Another airframe, number 95006, has been undergoing static testing at Novosibirsk.