F-35: voli di test sospesi

[Phant]

F-35 flights suspended

Flight tests of the F-35 Joint Strike Fighter have been suspended following the discovery of issues with fuel-system software on all variants and with a door hinge on the short-takeoff-and-vertical-landing (Stovl) version.

The Defense Department says flights are suspended temporarily pending modification of software that controls the engine's three fuel boost pumps. Incorrect signal sequencing that could trigger a shut-down of all three pumps was discovered in the laboratory.

Manufacturer Lockheed Martin originally said flights were restricted to below 10,000 ft., the altitude below which boost pumps are not required, but the Pentagon says all flights were suspended earlier this week as a "routine" safety precaution.

Flights in Stovl mode were suspended last week after post-flight inspection revealed an issue with the auxiliary-inlet door hinge on test aircraft BF-1. Efforts to find the root cause of the hinge problem and identify a solution continue.

A fix for the fuel-pump issue has been identified and is being tested. Software modified to correctly align the pump sequencing is to be loaded on to aircraft at Naval Air Station Patuxent River, Md., and Edwards AFB, Calif., test centers beginning Oct. 5.

"The impact to the flight test schedule is unknown at this time," Lockheed spokesman John Kent says. While testing of the conventional-takeoff-and-landing (CTOL) F-35A and F-35C carrier variant (CV) remain ahead of plan for the year, Stovl testing is significantly behind schedule.

Four Stovl F-35Bs at Patuxent River completed only 19 flights in September against a plan of 28, for a year-to-date total of 141 compared with 181 envisioned.

Testing of two CTOL F-35As at Edwards is ahead of schedule, with 17 flights in September against a plan of 18, for a year-to-date total of 114 compared with 53 envisioned.

The F-35C did not log any of the five planned flights in September as aircraft CF-1 remains in final finishing, Kent says, but CV testing is ahead of schedule for the year with 14 flights logged against nine planned.

Overall, the F-35 test program has logged 269 flights so far this year, against a planned 243, but September was the first month this year that the program did not meet or exceed its goal, with 36 flights compared with 45 planned.

Testing remains on track to achieve the 2010 goal of 394 flights, Kent says, but Lockheed already has acknowledged that Stovl testing will not meet its targets for the year, and initial at-sea testing planned for March 2011 will be delayed.

FONTE: http://www.aviationweek.com/aw/generic/ ... 0Suspended

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