F-35B grounded after fueldraulic line failure

F-35B grounded after fueldraulic line failure 18 Jan 2013 Dave Majumdar

http://www.flightglobal.com/news/articl ... re-381264/

"The F-35 Joint Program Office (JPO) has temporarily grounded the Lockheed Martin F-35B short take-off/vertical landing (STOVL) variant of the tri-service stealth fighter after the failure of a fueldraulic line in the aircraft's propulsion system. The fueldraulic line powers the actuator for the F-35B's STOVL exhaust vectoring system.

F-35B flight operations have been suspended at NAS Patuxent River, Maryland, Eglin AFB, Florida, MCAS Yuma, Arizona, and at Lockheed Martin's production facility in Fort Worth, Texas...

...According to the JPO, the incident occurred on 16 January at about 10 am central time. "While initiating a conventional mode takeoff roll, the aircraft experienced a propulsion system fueldraulic failure prior to takeoff," the JPO says. "Following standard operating procedures, the pilot aborted takeoff without incident and cleared the active runway. There were no injuries to the pilot or ground crew. The jet was then safely towed to a maintenance hangar and secured."

Engineering teams are reviewing data from the incident in order to determine the root cause of the failure, the JPO says. Once Lockheed and the JPO understand what caused the problem, the JPO will make a decision on when it will lift the grounding and restart F-35B flight operations. "Determining the root cause and potential mitigating actions have the highest priority of the F-35B team," the JPO says. "Impact to SDD [system development and demonstration] execution and flight training operations is being assessed," the JPO says.

Static ground operations of F-35B STOVL aircraft will continue, the JPO says."

A bit more info at the jump.

More info from another source:

F-35B Flights Suspended Following Fueldraulic Failure Jan. 18, 2013 By AARON MEHTA

http://www.defensenews.com/article/2013 ... t|Topics|p

"...“An initial inspection discovered a detached fueldraulic line in the aft portion of the engine compartment near the bearing swivel module,” spokesman Matthew Bates wrote in an emailed statement. “This component is not used in the CTOL or CV variant aircraft. A team of Pratt & Whitney and Rolls-Royce engineers is investigating the cause of the incident and working closely with Lockheed Martin and the F-35 Joint Program Office to resolve the matter.”

Bates also noted that P&W engines have successfully completed almost 25,000 hours of testing, including 4,270 flight hours.

The fueldraulic system was highlighted as a potential issue in the annual report to Congress released this week by the Pentagon’s Operational Test and Evaluation office (OT&E). The report noted that part of the fueldraulic system was removed in 2008 to save 9 pounds.

The testers warned that the fueldraulic system leaves open the chance of a sustained fire if exposed, but noted that the program office “is accepting the increased vulnerability associated with the fueldraulic system and is currently not considering reinstating the fueldraulic fuses in the production aircraft configuration.”

Always more of the same from first post from top of page at the jump.

Another view...

UPDATE 1-Pentagon grounds Marine Corps model of F-35 fighter jet UK Reuters 18 Jan 2013

http://uk.finance.yahoo.com/news/1-pent ... 00335.html

"...The incident came just days after the Pentagon's director of testing and evaluation released an 18-page report detailing an array of problems which he said underscored the "lack of maturity" of the $396 billion fighter program.

Matthew Bates, spokesman for Pratt & Whitney, a unit of United Technologies Corp (NYSE: UTX - news) , which builds the engines for the singe-engine, single-seat fighter jet, said an initial inspection discovered a detached propulsion line in the rear part of the engine compartment.

The fueldraulic line is not used in the A- or C-models, which are still permitted to fly.

"A team of Pratt & Whitney and Rolls-Royce engineers is investigating the cause of the incident and working closely with Lockheed Martin and the F-35 Joint Program Office to resolve the matter," Bates said in a statement provided to Reuters.

He said there had been no previous issues with the component that triggered the grounding."

Far too early to pass judgement. Could be the fitting itself, bad metallurgy, chaffing, a loose clamp or a number of other things. Why has the flammability of the fuel in the hydraulic system become an issue? The majority of hydraulic system fluids are flammable. The only fluids that aren't are the specialized glycol water ones used in specialized applications like the steel industry. They're a PITA to work with since the are water based and at times corrosive. Have yet to see a good valve to close off a line automatically if it senses high volume flow due to a line break.

marksengineer wrote:Far too early to pass judgement. Could be the fitting itself, bad metallurgy, chaffing, a loose clamp or a number of other things. Why has the flammability of the fuel in the hydraulic system become an issue? The majority of hydraulic system fluids are flammable. The only fluids that aren't are the specialized glycol water ones used in specialized applications like the steel industry. They're a PITA to work with since the are water based and at times corrosive. Have yet to see a good valve to close off a line automatically if it senses high volume flow due to a line break.

marksengineer: Is it likely that the F-35 has flow sensors at various points, and if there is a significant leak, then it gets detected when flow exceeds the amount burnt by the engine? This may be why the didn't want to keep the fueldraulic fuses in the jet.

Remember the Air Transat A330 incident, where a fuel leak developed, but wasn't detected with the current configuration. Hopefully they learnt from those kind of SNAFUs.

Another day at the office..
Given time, it will be interesting to to compare the rate of hydraulic-related problems/ failures on the F-35 vs legacy platforms as well as the attendant maintenance effort entailed.

On the runway during T/O did 'Bitchin' Betty' say "I'm sorry Dave - No CTO today"?

In VL Mode, I guess that would have triggered,the auto-eject sequence. All ejections are stressful but on the B the pilot isn't going to have any time to brace before he's blasted out of the plane.

If you read the report closely you'll note that the live fire test article (i.e. AA-1) had the fuses in place. They didn't work and thus, were not only removed, but removed from future consideration.

popcorn wrote:In VL Mode, I guess that would have triggered,the auto-eject sequence. All ejections are stressful but on the B the pilot isn't going to have any time to brace before he's blasted out of the plane.

A 'guess' indeed...

Auto-eject only goes off if the plane begins to go out of control.

Nothing about this incident says the F-35B would have lost control.

Some info on the auto-eject is in this thread on this page: http://www.f-16.net/f-16_forum_viewtopi ... rt-30.html Video F-35 Ejection Hi Speed Test

"...Actuator encoder feedback to the aircraft databus is provided to allow automatic adjustment, helmet-mounted display information and zone restriction. This ensures that pilots cannot put themselves in a potentially unsafe position by transgressing, for example, the forward ejection clearance line or their proximity to the canopy.

An auto-eject system has been introduced to counter the lift-fan failure condition for the F-35B STOVL (short takeoff vertical landing) aircraft...."
&
"...Neck protection is provided by means of a “Catcher’s Mitt” inflatable device which supports both sides of the pilot’s helmet and also provides support to the top and /back of the helmet. This device is also held in a container located behind the pilot’s head. The device is vented before the parachute is deployed. The device has been tested and proved to inflate under simulated 50,000 ft altitude conditions.

The F-35-B (STOVL) aircraft has additional failure modes associated with Lift Fan, Vane Box, Lift Fan Drive Shaft, Roll Duct and Turbine failures. A typical pilot takes two seconds to react to the ejection klaxon or one second if warned in advance of a likely failure. In the case of a STOVL related failure, ejection must take place within 0.6 seconds. Hence it was necessary to install smart failure sensors on the aircraft to automatically fire the ejection circuit mounted in the back of the seat....

BOTH quotes on the same page at URL above.
&
On the next (last) page: Tomlinson quote:

"...In the unlikely event of the lift fan failing catastrophically the aircraft would pitch inverted in 0.6 seconds, and the pilot is protected by auto-ejection signalled by pitch rate and attitude (derived from the YAK 38 & 141 systems)...."

SpudmanWP wrote:Auto-eject only goes off if the plane begins to go out of control.

Nothing about this incident says the F-35B would have lost control.

Yeah, ]'m,really speculating but it,would be a fine line where the thresh hold is before a malfunction in VL mode graduates to loss of control hence the hair trigger on auto eject..,but I guess to a ,computer,operating in nanoseconds, mere milliseconds go by at a turtle's pace.

SpudmanWP wrote:Auto-eject only goes off if the plane begins to go out of control.

Nothing about this incident says the F-35B would have lost control.

Yeah, ]'m,really speculating but ir,would be a very fine line where the thresh hold is before a malfunction graduates to loss of control hence the hair trigger on auto eject..,but I guess to,a,computer,operating in,nanoseconds.mere milliseconds,go by at a turtle's pace.

F-35B grounded following fuel leak during takeoff By Sue Book, Sun Journal Staff 19 Jan 2012

http://www.newbernsj.com/news/local/f-3 ... ff-1.81538

"...According to information provided from NAVAIR by the military legislative adviser for Rep. Walter B. Jones, R-Farmville, “The takeoff was safely aborted with no secondary damage. Updates will be provided once further information is available or corrective action is established.”

A nozzle for the “fueldraulic line failure… resulted in a significant fuel leak during the takeoff roll of a UK-owned, Eglin-based F-35B.”

The email forwarding the advisory to area officials and community leaders interested in successful development the Joint Strike Fighters’ most complex version, was prefaced with “Bad news, but as all of you know, new aircraft are going to experience problems, e.g. V-22, Dream Liner, etc.”

Harry Blot, retired Marine Corps lieutenant general and a former program manager with Lockheed Martin’s JSF development, said, “I wish it hadn’t happened but it is the type of thing that comes as part of the analysis. It’s good that if something was going to break, nobody got hurt and the airplane wasn’t damaged.”

“The part is made by Rolls Royce under contract to Pratt and Whitney,” he said. “It is actually the tail pipe which rotates down to get the thrust you need for swivel operations. It failed. Now they have to figure out why. It just came out of maintenance. Was it something somebody did wrong or something wrong with the design or manufacture apt to recur? They have to sort it out.”

“NAVAIR is responsible for technical help for all of these aircraft and when they get an incident, they look at it and say ‘Stop flying the airplane until I get a chance to see what happened,’” Blot said. “It could be a one-of-a-kind incident and you go on. It could mean this has to be fixed. Some evaluations take less than a day. Others take much longer.”..."