Reports of F-35B Crash/Pilot Ejection MCAS Beaufort

aasm · by **aasm** » 16 Oct 2018, 15:29

smsgtmac wrote:
spazsinbad wrote:
Most F-35s return to flight operations after fuel tube problem
15 Oct 2018 Valerie Insinna

... “Pratt & Whitney is rapidly procuring more parts to minimize the overall repair timeline for the remaining jets. Current inventory will restore about half of the impacted jets to flight operations [10%], and the remaining aircraft [10%] are expected to be cleared for flight over the coming weeks.”..."

Source: https://www.defensenews.com/air/2018/10 ... e-problem/

Thanks Spaz, I've been sitting on info for days wanting to scream "it was a (relatively) easy-to-replace engine fuel tube!" (which still may not be the root cause BTW). Sounds like Pratt is stepping right up to the problematic tube.

Just think. if it had been a twin engine jet the lot buys would have been twice as large doubling the number of problematic tubes and perhaps the number of fuel leaks. What kind of cascading power failures would have been experienced? (Power transfers can be a hard problem) And NOT to "troll" or anything like that but what was the number of F-22's that couldn't be flown out of Tyndall were there because of something needed for one engine? Just Asking.

Or it would not have crashed. Noone knows for sertainty

SpudmanWP · by **SpudmanWP** » 17 Oct 2018, 20:18

Apparently the fuel tube is in an easily accessed location (no need to pull the engine?) as Hill AFB maintainers were able to check all of their jets in less than a day.

As part of the inspection process, F-35s maintenance crews removed and replaced faulty fuel tubes. Garbarino said maintainers at the 388th FW completed their inspections the same day flights were suspended and resumed flying operations later that afternoon.

More at the JUMP
https://www.standard.net/news/hill-s-f- ... 42760.html

steve2267 · by **steve2267** » 17 Oct 2018, 21:13

I have been in contact with an F-35 wrench bender. He stated that a combination of ALIS and physical inspections would take care of the issue. I did not press him on to what extent ALIS could ameliorate or remove the need for physical inspections. However, he did confirm the part in question was on the engine "side" rather than on the airframe, and that pulling an engine was not required -- it could be inspected and/or replaced without pulling the motor. FWIW.

Dragon029 · by **Dragon029** » 17 Oct 2018, 22:12

The Dutch TES Commander's twitter mentioned that it was a "fuel hydraulic" tube, which sounds to me like a fueldraulic line. If that's the case it might have been the line that actuates the convergent-divergent nozzle on all F-35s; I'm not sure what other actuators (if any) use fueldraulics on the A and C variants.

SpudmanWP · by **SpudmanWP** » 17 Oct 2018, 22:28

Australia says the same thing.

Two of Australia’s new $100 million F-35 strike fighters have been found to contain “suspect hydraulic fuel tubes” requiring replacement, Defence has confirmed.

https://www.theaustralian.com.au/news/n ... 4y8Z-PYjGU

spazsinbad · by **spazsinbad** » 17 Oct 2018, 22:37

Could not get past that Oz subscriber URL so found this one: https://www.theaustralian.com.au/news/n ... a343676f8d

Two new fighter jets with faults still grounded, seven cleared: ADF
17 Oct 2019 Rory Callinan

"Two of Australia’s new $100 million F-35 strike fighters have been found to contain “suspect hydraulic fuel tubes” requiring replacement, Defence has confirmed.

The problems were uncovered as a result of the crash of a US Marine Corps operated F-35B aircraft in the United States on September 28. All operational planes had been grounded after the crash including Australia’s small US-based fleet.

An investigation was then undertaken into the cause of the South Carolina crash which involved the pilot ejecting safely and the aircraft being destroyed.

US authorities then concluded the crash was likely related to faulty tube causing fuel supply problems and all aircraft were then subject to an inspection of the fuel tubes.

An Australian Defence Force spokesman today said two out of Australia’s nine F-35 aircraft were found to have been fitted with suspect hydraulic fuel tubes which would be replaced.

He said all non-affected Australian aircraft had now been cleared to fly and the safety inspections have not affected the delivery of the first two aircraft to Australia in December.

The spokesman did not provide any detail as to how much the fix might cost or who would be paying for the repair.

The Australian has sought comment on this issue from the F-35 Joint Program Office in the US.

US military authorities have previously declined to say exactly how many of their aircraft were affected by the problem but local defence media sources estimated the numbers could be about 60 planes.

Earlier this week the US authorities cleared about 80 per cent of the military’s F-35s to return to flying...."

Source: https://www.theaustralian.com.au/news/n ... a343676f8d

quicksilver · by **quicksilver** » 17 Oct 2018, 23:23

Fueldraulics...remember this?

viewtopic.php?f=22&t=22024

spazsinbad · by **spazsinbad** » 18 Oct 2018, 00:16

Cor blimey Guv that was nearly six years ago. Good info on the fuelDEhydraulico though. :roll:

quicksilver · by **quicksilver** » 18 Oct 2018, 00:20

Just another data point.

Fuel runs all over the jet doing a variety of things, including cooling functions. Thus, we are likely a long way from root cause.

Dragon029 · by **Dragon029** » 18 Oct 2018, 03:21

We do know however that the fueldraulic line in question was on the engine itself, with the tube having a seemingly known manufacturing (vs design or contamination / blockage) defect. I'd suspect that it came loose or cracked (if it was metal) / split, possibly due to an incorrect material being used, or due to something like diameters not being correct.

Gums · by **Gums** » 18 Oct 2018, 15:40

Salute!

Yeppers, may not be actual JP-4 or 5 used for hydraulic purposes, but no kidding "brake fluid" like we use in our autos for clutches and brakes.

Wondering if it was a connection versus an actual split in a tube. And what was the exact gizmo? Nozzle opening for AB or for rotation and deflection in the Bee? And so forth.

Question for Viper and Eagle wrenchbenders/engine troops? Is the nozzle drive train driven by a hydraulic motor? The zip-zip-zip sound is very noticeable if the pilot is moving throttle around a lot.

Gums ponders...

quicksilver · by **quicksilver** » 18 Oct 2018, 16:33

Actual fuel is used. Link for historical reference -- http://aviationweek.com/awin/troublesom ... ved-f-35bs

If you root around you'll find that fueldraulics are used on other things too, like the Saturn V boosters.

Dragon029 · by **Dragon029** » 18 Oct 2018, 17:01

Gums wrote:Wondering if it was a connection versus an actual split in a tube. And what was the exact gizmo? Nozzle opening for AB or for rotation and deflection in the Bee? And so forth.

It'd be the nozzle opening for AB, otherwise the tube being inspected / replaced wouldn't be found on the F-35A and C. And on the F-35, fuel is used as the hydraulic fluid to actuate the convergent-divergent nozzle; the fuel is then sent back to the middle of the engine to go into the injectors and get burned.

The advantage of this system is that it can help vapourise the fuel / make it mix and burn better, plus it means you have one less connection between the engine and fuselage that you need to connect / disconnect whenever you're removing it.

marsavian · by **marsavian** » 26 Oct 2018, 12:23

https://www.marinecorpstimes.com/news/2 ... spections/

The F-35 Joint Program Office temporarily has halted flight operations for a number of F-35s with higher flight hours after finding two new parts that will require inspection on older models of the jets.

A spokesman for the F-35 JPO, who confirmed the issue exclusively to Defense News and Marine Corps Times, declined to detail exactly how many jets may possibly be grounded as a result of the inspections. However, one source close to the program said that only a couple dozen F-35Bs meet the criteria where an operational pause would be necessary.

“The joint government and industry technical team has completed their assessment of the fuel supply tubes within the Pratt & Whitney engine on F-35 aircraft,” the F-35 Joint Program Office announced in a statement. “In addition to the previously identified failed tube, the analysis has identified two additional fuel supply tubes that require inspection.”

Some of the older engines with higher flight hours may require additional fuel tube replacements.

steve2267 · by **steve2267** » 26 Oct 2018, 16:56

It was unclear from the twittering aerospace aviation reporters whether the engine will have to be pulled to inspect and possibly replace these two other fuel tubes. One tweet said the engines had to be pulled. Another tweet referred to a web "article" that stated the engines did not have to be pulled. As pulling an F135 and replacing is a 5-7 hour process... that is no small task.

What is a fuel "tube" anyway? I know what a tube is. And I'm familiar with fuel "hoses"... but what is a tube? Is it the shunt to which is affixed a hose?

With all the recent announcements about "fuel tubes", the accident is beginning to sound like a fuel starvation incident, although a failure in a fueldraulic system, esp. during a Mode 4 STOVL transition would not be good.