"We are not ruling out that deliveries of the Superjet 100 aircraft to the first clients will be postponed over a delay in certification tests," UABC CEO Alexei Fyodorov said.
He added that the first test flight was planned for next month.
Originally, the first Superjet 100 deliveries were to be made in late 2008.
The Superjet 100 project is a family of medium-range passenger aircraft developed by the Sukhoi Design Bureau in cooperation with major American and European aviation corporations, including Boeing, Snecma, Thales, Messier Dowty, Liebherr Aerospace, and Honeywell.
Sukhoi aircraft manufacturer successfully tested Superjet 100 engines in mid-February.
The company plans to manufacture at least 700 Superjet 100s, and intends to sell 35% of them to North America, 25% to Europe, 10% to Latin America, and 7% to Russia and China.
Mikhail Pogosyan, Sukhoi's general director, said in January that the company had secured 73 solid orders for the aircraft.
The list price of a 95-seat base model is $28 million, but the company is currently working on both smaller and larger capacity modifications.
The market for the Superjet 100 is estimated at around $100 billion for around 5,500 planes, through to 2023.
