FARNBOROUGH, England (AP) - Boeing Company executives say the timetable for the first test flight of the 787 remains on schedule for the fourth quarter, but it's going to be tight.

Program manager Pat Shanahan said the manufacturer is working to fix a recently discovered brake problem. That fix is critical for the new plane to receive hardware qualifications in the next month or so.

Speaking Tuesday at the Farnborough Airshow in Britain, Shanahan said it is a certification problem, rather than a functionality problem. He said he is confident the fix will be made in time because the subcontractor involved in General Electric.

The 787 has been touted by Boeing for greater fuel-efficiency potential because it's the first large jetliner to be built mostly from lighter, carbon-fiber composites.

Meanwhile, another batch of airplane orders was announced today and most went to Boeing's European rival, Airbus. Qatar Airways is getting four Airbus A321s worth $360 million at list prices and took options on two more, and Tunisair firmed up a deal for 16 Airbus jets worth nearly $2 billion. The Tunisian carrier's deal was announced initially in April.

Boeing got an order from Arik Air of Nigeria for seven 737s. The Russian aircraft maker Sukhoi announced that Avialeasing is buying 24 Superjet 100s valued at more than $630 million at list prices. Avialeasing also took an option on 16 additional planes.