Forum: F-35 Lightning II

F-35 Flights Restricted By Fuel Pump, Inlet Door Issues

Oct 1, 2010

By Graham Warwick graham_warwick@aviationweek.com
WASHINGTON

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

A precautionary restriction limiting flights to below 10,000 ft. was imposed this week after ground testing uncovered a software anomaly that could cause a fuel boost pump to shut down in flight. The boost pump is not required below 10,000 ft., manufacturer Lockheed Martin says.

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. Conventional-mode flights below 10,000 ft. will continue, spokesman John Kent says.

Lockheed expects both restrictions to be lifted shortly. “The impact to the flight test schedule is unknown at this time,” 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.

Working with fuel-system software supplier BAE Systems, Lockheed says a fix to the boost-pump issue has been identified and is being tested in the laboratory. Efforts to find the root cause of the inlet-door hinge problem and identify a fix continue.

Four Stovl F-35Bs at the Naval Air Station Patuxent River, Md., test center completed only 19 flights in September against a plan of 28, for a year-to-date total of 141 compared with 181 planned.

Testing of two CTOL F-35As at Edwards AFB, Calif., 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 planned.

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 flight 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 has already acknowledged that Stovl testing will not meet is targets for the year, and initial at-sea testing planned for March 2011 will be delayed (Aerospace DAILY, Sept. 17). Bang Head

http://www.aviationweek.com/aw/generic/ ... dline=F-35 Flights Restricted By Fuel Pump, Inlet Door Issues&channel=defense

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Obviously the whole program is a complete failure and we need to cancel it as soon as possible...

SHORT URL will take you there (to original): http://alturl.com/jr54k

SHHEEESSHH!!! Flights suspended now [Addon to Post above]

F-35 Flights Suspended Oct 1, 2010 By Graham Warwick

http://www.aviationweek.com/aw/generic/ ... dline=F-35 Flights Suspended
OR
http://alturl.com/ourdg

"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."

NevaMind the cavalry are coming....

Software Fix En Route to Grounded F-35s Posted by Graham Warwick at 10/1/2010

http://www.aviationweek.com/aw/blogs/de ... d=blogDest
OR
http://alturl.com/ebpjm

"Flight testing of the F-35 is expected to resume early next week after being suspended since early this week after a problem with the software controlling the fuel boost pumps was discovered in the lab. Modified software is to be loaded onto the test jets beginning Oct. 5.

Lockheed Martin originally said all F-35 variants were restricted to flying below 10,000ft, the altitude below which the boost pumps are not required. But the Pentagon now says all flights have been suspended as a routine safety precaution.

Meanwhile, STOVL-mode flying with the F-35B has been suspended since late last week because of an issue with an auxiliary-inlet door hinge on aircraft BF-1 - the only one instrumented for vertical landings. The cause of the hinge problem, and a fix, have not been found yet.

Precautionary groundings are indeed routine in development programs, but in this case they only increase the pressure on a flight-test program already running late. Lockheed still expects to meet its target of 394 flights this year, but only because the two CTOL F-35As at Edwards are so far ahead of plan - 114 flights so far this year against a plan of 53.

The F-35C carrier variant is also ahead of schedule - 14 flights against 9 planned - even through aircraft CF-1 did not return to flight in September as expected and remains in final finishes.

But the latest suspensions only heap woe onto the F-35B test program, running well behind with a year-to-date total of 141 flights against a plan of 181 - despite there being four aircraft at Pax.

With Congress back at work finalizing the FY2011 defense budget, the F-35 grounding and test-stand failure of a GE/Rolls F136 alternative engine will provide much grist to the political mill.

NOTE: The issue with the software controlling the fuel boost pumps involved incorrect signal sequencing that could trigger a shutdown of all three pumps and cause the engine to stall. The problem was found in the lab and not in flight. The software fix correctly aligns the sequencing.

Prinz_Eugn wrote:

Obviously the whole program is a complete failure and we need to cancel it as soon as possible...

No, but I'd keep a closer eye the bravo. The complexity issues look like they might be coming to pass. Not time to pull the plug quite yet, but if it continues to have issues...

I'm confident that the country that put men on the moon can fix a hinge problem...

It's a flight test program. The purpose is to find problems and correct them. The issue is that finding and correcting everything takes a certain amount of time and the schedule does not exactly factor in any of this normal delay. Indeed as GAO has pointed out repeatedly the program lists zero required time for software issues which is of course ridiculous as opening a 2nd software shop clearly indicates. There will be dozens more issues like this and it's perfectly normal and should be expected.

Now all that said it's also not responsible for supporters of the program to continually see everything through rose colored glasses. We do not know what we do not know hence we have a test program to discover these things. Nobody can be certain whether this adds up to delay in the program some years from now and those who propose some level of prudence and observe the program is likely to face further delays should not be dismissed or insulted given that's where the safe money would bet in the first place.

Well said lb, though I fully expect the likes of Chicken Little, sorry, Bill Sweetman to make a meal out of this though

Shep:

If Sweetman has some schadenfreude going at this point, and indulges in some "told you so", it's because the deputy program director told him to:

http://www.flightglobal.com/blogs/the-d ... -f-35.html

Context: Moore had just confidently predicted that all 12 SDD jets would be at government test centers by now, averaging 12 sorties per month each.

I realise you can't resist white knighting Bill but that video proves nothing as the "I told you so" part came right at the end of the video and what was said after that was conveniently chopped from the clip... It was a cute editing trick that journalists are fond of.

That's it, of course.

Trimble edits the clip so that it will make Sweetman (who works for his competitor) look good a year later.

ITS A CONSPIRACY I TELL YA

Not really, but you have to wonder why the rest of it isn't shown. Anyway wait and see, Bill will make a meal out of this.

lb wrote:

It's a flight test program. The purpose is to find problems and correct them.

The purpose of a flight test program is also to find out if the program is viable for field deployment.

The entire life the JSF program, people have been acing the F-35B is a proven commodity because the Harrier works. They leave out of the fact that the F-35B uses a completely different and more complex system.

The software problem should be no big issue. You can do almost anything with software. Once they find the fix, they'll just load the s.w. and reboot. They'll keep on testing for the bug but it won't be the end of the world.

The hinge problem seems minor but that's a hardware issue, meaning if they can't find a solution to it using the existing airframe, they'll have to redesign. Which is a pain in the a$$ because it may affect other components that are working just fine right now. Hopefully it won't turn out to be that big of a deal.

Better to find flaws and iron out the kinks now than when the plane is in full production.