The Lockheed Martin F-35 programme received a double boost on the eve of the Paris air show with an order commitment from a fourth international customer and the passing of several key milestones in flight test.
Norway's parliament on 17 June approved the purchase of four F-35s during the low-rate initial production phase, joining Israel, Netherlands and the UK among the first confirmed foreign buyers. The USA has ordered more than 60 F-35s in the first four lots of low-rate initial production.
The F-35 flight-test programme also continued showing signs of gathering momentum following several years of delays. After completing 410 flights in 2010, Lockheed's test fleet has already exceeded that total within the first half of this year.
With all 13 flight-test jets finally delivered, Lockheed is also on pace to exceed the programme's goal of completing 872 flight tests in 2011.
Meanwhile, the conventional take-off and landing variant AF-1 has recorded a top speed of Mach 1.53, coming within M0.07 of the F-35's required limit.
Both the international commitments and the flight-test milestones come at a critical time for the programme.
Since February last year, the Department of Defense has restructured the baseline schedule and cost estimates twice, adding several years and more than $100 billion to the development and acquisition of the stealth fighter.
Meanwhile, key US lawmakers, including Sen John McCain, have been increasingly vocal over concerns about the programme's cost and technical setbacks.
Amendments to the defence authorisation bill passed on 17 June by the Senate Armed Services Committee, which includes McCain among its members, reflects these concerns.
The bill requires Lockheed to accept a fixed-price contract for the next batch of 32 aircraft ordered in the fifth lot of low-initial production. If the bill makes it into law, Lockheed also must absorb all cost overruns.
Lockheed previously agreed to sign a fixed-price contract in low-rate initial production two years early, but the agreement includes provisions for the government to share the costs of some overruns.