Lockheed Martin’s F-35 Joint Strike Fighter has been earmarked as a possible replacement for 556 Boeing Super Hornets for the US Navy, potentially doubling the number of aircraft the Navy intends to buy.

Flight International reports a May 31 disclosure by the US Department of Defence (DoD) to Congress. The DoD report, dated from March this year, looks at the Navy’s options over the next thirty years.

The US Navy has been planning to purchase 220 F-35Cs to replace older-model F/A-18C/D Hornets and is currently buying new F/A-18E/F Super Hornets. However, it is already analysing options for a replacement programme starting after 2020 called the next-generation air dominance (NGAD) fighter.

The F-35 could replace all of Boeing’s 556 strong fleet of F/A-18E/F Super Hornets for the US Navy after 2025. However, the DoD report also looks at alternatives including F-35s, a new unmanned or manned platform, or both.

This is bad news for Boeing, which is offering its Super Hornet as an alternative to the delayed, over budget F-35. "Given the many variables involved in the procurement process, especially over such a long timeframe, it would certainly be a challenge for any company to project the full impact of the plan at this time," the company said. "Boeing supports the navy's stated position that the Super Hornet is the navy's premier frontline strike fighter today and that it will remain so through 2035."

The development of the multi role F-35 Joint Strike Fighter, due to replace various aircraft in the military fleets of both the United States and its partners, has been hampered by delays and ballooning costs. The operational testing of the F-35 - being developed by Lockheed Martin and Britain, Italy, Netherlands, Turkey, Canada, Australia, Denmark and Norway - is not expected to begin until 2017.

The US$382 billion F-35 program came under fire for rising costs at a Senate hearing last month, but Lockheed Chief Executive Robert Stevens has said he was confident the company could resolve development challenges facing the programme. The F-35 is expected to account for more than 20 percent of Lockheed's global sales once it enters full production.

Carter told the committee that buying the planned 2 443 F-35 planes for the US Air Force, Navy and Marine Corps was estimated to cost twice as much in real terms as originally expected. Carter said that price was "unacceptable and unaffordable," but expressed confidence that the Pentagon would be able to trim excess costs in the coming months and years.

The Government Accountability Office, the investigative arm of Congress, estimates that development of the new warplanes will cost a total of US$56.4 billion and conclude in 2018, a 26 percent cost increase and a five-year schedule slip from the program's current baseline.

The total cost of operating and maintaining the new planes over coming decades is expected to top US$1 trillion, according to Pentagon estimates, but defence officials and industry executives say they are working hard to reduce those costs.

One initiative taken was to cancel the alternative F136 engine. Rolls-Royce/General Electric have asked the DoD to let them complete the engine at their own cost. All they require is access to the engines and test facilities.