Innovation in tight spaces [F-35A Engine Change Time Taken?]

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
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spazsinbad

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Unread post04 Jan 2019, 21:14

Innovation in tight spaces
02 Jan 2019 Staff Sgt. Peter Thompson, 33rd Fighter Wing

"EGLIN AIR FORCE BASE, Fla. -- As Hurricane Michael churned toward the Emerald Coast of Florida, F-35A Lightning IIs from the 33rd Fighter Wing here evacuated to Barksdale Air Force Base, La., to avoid the storm’s path and potential catastrophic damage. As Michael passed, narrowly missing Eglin, a different type of storm brewed on the horizon that would test Nomad innovation. There was talk within the F-35 community of a one-time inspection (OTI) order being passed down.

Every aircraft at the 33rd FW needed to have a fuel line on the engine inspected. Parts within a specific batch number needed to be removed and replaced. All of the wing’s aircraft were grounded until they were inspected and fixed if needed. This had a profound impact back at Eglin but brought even more complications for the aircraft still at Barksdale.

“It was particularly worrisome for us because we had jets off station without access to all of our tools and personnel,” said 1st Lt. Patrick Michael, 58th Aircraft Maintenance Unit assistant officer in charge. “We didn’t have the guidance for changing out the part yet. The preliminary guidance said we would need to remove the engine to access and remove the line.”

The current guidelines used for aircraft maintenance required that the entire engine be removed, which would require at least 36 hours per jet. Furthermore, engine trailers and tool boxes would need to be transported to the location, extending the timeline. When the OTI was made official on October 12, leadership at all levels of the 33rd Maintenance Group and 33rd Aircraft Maintenance Squadron saw an opportunity for Airmen to demonstrate how capable they are. They extended a challenge… find a better way.

The maintainers at Barksdale determined eight of the jets there failed the requirements of the OTI. The remaining jets returned to Eglin. Maintainers working with field support engineers from Lockheed Martin and Pratt and Whitney set out to find a way to replace the fuel line without removing the engine. Crew Chiefs determined they could access the part through a hole just big enough to fit a hand. The location of the fuel line is nearly impossible to see. They needed to detach and set aside another component without removing it, making room even scarcer.

Despite how difficult it was, they succeeded in finding the fix. The first across the F-35’s global presence. Within three days of the official notification, the 58th AMU had identified the jets that were deficient, found the fix, got it reviewed and approved to execute and were on their way to Barksdale to implement the new procedure.... [more at jump]

...To this date, only one other unit has replicated the same maintenance on three jets. This is because of what sets the 33rd FW maintenance team apart from others.

“The maintainers at the 33rd Fighter Wing have a maturity unlike anywhere else in the enterprise,” said Joseph Frasnelli, Lockheed Martin Aeronautics F-35 chief of maintenance and operations at Eglin. “The 58th AMU forged their own path with their leadership’s support… and they knocked their (fuel line changes) out in a significantly quicker time.”

When the OTI was first accomplished, the fuel line swap took about 24 hours, 12 hours less than removing the entire engine and performing the maintenance on a stand. As they repeated the task on additional aircraft they were able to shave another four hours from that time, enabling jets to return home faster. That speed and accuracy ensured the wing could continue accomplishing one of its primary missions, training F-35A pilots...."

Source: https://www.aetc.af.mil/News/Article/17 ... ht-spaces/
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post04 Jan 2019, 21:31

When the OTI was first accomplished, the fuel line swap took about 24 hours, 12 hours less than removing the entire engine and performing the maintenance on a stand.


The 36 hours (not likely a 24 hr per day op) includes removal, disassembly, testing, new tube, testing, replacement, and final LO coating test.

Don't forget that since you need to check all of your jets, man hours and engine carts & tools are in short supply.

Here is another source that pooh-poohs the the 36-hour to just remove myth.

"The primary goal following any mishap is the prevention of future incidents," Joe Dellavedova, the director of public affairs for the F-35 program, said in a statement. "We will take every measure to ensure safe operations while we deliver, sustain and modernize the F-35 for the warfighter and our defense partners."

Dellavedova said that they will remove and replace any fuel tubes they suspect might be problematic. Those planes that don't have the problem will be cleared to fly, he said, and they hope to have the inspections completed within 24 to 48 hours.


https://www.nbcnews.com/news/us-news/pe ... st-n919311

Obviously if it took 36 hours to just remove it then the whole inspection process would take 80+ hours which is impossible in the "24-48 hour" timeframe given above.
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Unread post04 Jan 2019, 21:32

Hopefully an F-35 mech will stop by and give us some relevant numbers based on 1st-hand experience.
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Unread post04 Jan 2019, 21:54

Thanks 'SWP' - I went looking for F-135 engine change times recalling an engine change aboard WASP during an OT supervised by a Brit 'Beth' (still looking) and meanwhile found this about engine change for the SHAR - just for context....
Acquisition of Capabilities through Systems-of-systems: Case Studies and Lessons from Naval Aviation
22 Apr 2009 Dr Michael Pryce

"...In addition, the need to remove the wing of the Sea Harrier [SHAR aboard a CVS] in order to change its engine meant that a specialised hoist was installed in the hangar, with an engine change requiring the aircraft to be trestled and secured to the hangar floor. The entire engine change evolution could take several days, monopolising a major part of the hangar and reducing the scope for aircraft movements in the hangar (Andrews, 2009, February 12; Davies & Thornborough, 1996)...."

Source: http://acquisitionresearch.net/_files/F ... 09-010.pdf [no longer valid]

Searching Beth + engine found this: viewtopic.php?f=22&t=27345&p=291817&hilit=Beth+engine#p291817 [butno time]
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post04 Jan 2019, 22:17

Here is the "Acquisition of Capabilities through Systems-of-systems: Case Studies and Lessons from Naval Aviation" PDF

download/file.php?id=13733
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steve2267

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Unread post04 Jan 2019, 23:13

SpudmanWP wrote:Hopefully an F-35 mech will stop by and give us some relevant numbers based on 1st-hand experience.


A former Viper mech with several years working on the F-35 tells me it takes about 8 hours for a crew of six to swap an F135 if they have all the tools and necessary equipment on hand. He says it actually takes less on a "B" as all the doors opening gives better access. In his opinion, the F135 is better than the F110/F100 and the integrity of the motor has been very good. Without orders to go looking for something specific, he figures they only have to pull a motor once every 8 or 9 months. Overall he has been very happy / pleased with the F135 from a maintenance perspective.

ETA: Absent any tech or upgrade orders, the motor can run over 2k hours between service cycle inspections.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post05 Jan 2019, 00:25

'Stevie' that sounds like a ball park figure for sure. Now I can recall an old 'magazine' PDF story about engine - but find it?
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post05 Jan 2019, 00:31

I thought the F100 / F-16 had been designed to be able to do an engine swap pretty quickly. When this fellow told me it took so long, I was a little taken aback. (FWIW, I think the 8 hours does not necessarily include a bunch of checks / regression tests / and ops testing. Just disconnect all the bits, pull the motor, put in a new one, and re-connect all the bits.) But he said the damn thing is (and was designed to be) so durable, they "rarely" need to pull a motor. He is pretty impressed by its "resistance" to bird strikes etc. I believe we all yakked about a story recently where a Lightning ingested some nasty bits (from a re-fueling basket?) and kept on going. Burp. All in all, this mechanic with whom I have corresponded has been very impressed by the F135 and likes it (and the F-35 for that matter) a lot.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post05 Jan 2019, 00:45

Search on Kjelgaard for more good engine info in this forum however I'll recreate this bit from 2012 whilst PDF is here.

search.php?keywords=Kjelgaard&terms=all&author=&fid%5B%5D=65&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=-1&t=0&submit=Search

doobydoobydoo: Engine F135 & LiftFan STOVL F-35LightningII pp6ed.pdf download/file.php?id=19133 (PDF 1.5Mb)

Another Engyn story 2014 (I'll have to find the PDF now): viewtopic.php?f=56&t=25691&p=274954&hilit=Kjelgaard#p274954
Powering the Lightning II
26 Apr 2012 Chris Kjelgaard

"...Maintainability
From the outset the F135 has been designed for maintainability, building on the experience Pratt & Whitney gained with the F100 for the F-15 and F-16 and then with the F119 for the F-22. (When designing the F119, the company brought in US Air Force mechanics to help design its engine-mounted controls and accessories for maintainability). In the F135, all controls affixed to the casing are ‘single-deep’ – no control units are mounted on top of each other – and the nuts and bolts which attach them to the engine casing are encapsulated in the control assemblies themselves, so nuts and bolts stay with the control units when these are removed. This greatly minimizes the risks of nuts and bolts being lost and causing foreign-object debris (FOD) damage.

Similarly, all engine clamps and blocks stay on the engine casing when an F135 is removed for maintenance and the engine uses no safety wire, eliminating another potential source of FOD damage. All controls and accessories are mounted on the bottom of the engine, making it easier for mechanics to get to them; and these assemblies are modular so that, say, a mechanic could easily remove the electronics or valves or relays for an F135 fuel control unit as entire modules.

O’Donnell says the US Air Force has found the F119 to be “significantly more maintainable” than the earlier F100 – the F119 offers “major orders” of improvement of mean time between failures in terms of maintenance man-hours required – and says P&W expects operators to find the F135 even more easily maintainable and reliable than the F119. Another plus, he says, is that P&W can apply the design-for-maintainability improvements it has developed for the F135 to new F119 production batches as well....

...So seriously did P&W take the job of making the F135 highly maintainable that it tried to design the engine to require only a single hand tool, clamped to the engine when not in use, for all line maintenance jobs. P&W couldn’t quite achieve that ideal but did succeed to the point where only six hand tools are required....
&
...Another key feature of the F135 is its augmentor, or afterburner system. While available details of the augmentor are sketchy, the F135 is known to employ multi-zone (probably three-zone) fuel injection aft of the afterburner’s pilot light. These zones inject fuel independently, so that the afterburner does not act in an all-or-nothing way but instead provides a variable range of additional, smoothly transitioning wet thrust at the pilot’s command. Also, like the F119 augmentor, the F135 augmentor is stealthy: The design of the two engines’ augmentors places multi-zone fuel injection into curved vanes which eliminate conventional spray bars and flame holders and block the line of sight to the turbine when looking into the engine from behind....

Source: http://militaryrussia.ru/forum/download ... p?id=28256 [PDF 12.8Mb] also in forum somewhere
Last edited by spazsinbad on 05 Jan 2019, 00:56, edited 2 times in total.
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post05 Jan 2019, 00:52

What this mech has told me based on his experience the last 4-6ish years seems to confirm what that 2012 article stated.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post05 Jan 2019, 02:04

PDF has probably been posted however some of the relevant pages will be reposted here about the engine & stuff from:

AIR International F-35B Special Oct 2015 F135 Engine Trailer aboard USS WASP JPG is in one of the stories.

60 page PDF attached below: F-35B & ENGINE Special 60 Pages AIR_Intl_October_2015_UK ed.pdf
Attachments
F135engineTrailerOTusmcTestWasp.jpg
F-35B & ENGINE Special 60 Pages AIR_Intl_October_2015_UK ed.pdf
(6.49 MiB) Downloaded 87 times
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post05 Jan 2019, 16:32

I've seen our Engine Shop remove an F100 from a Viper in less than 2 hours once all the panels are removed and required disconnections are completed. What leads to loss of time is getting structural to check the rail with a micrometer and any anomalies in the bay: damaged lines, tubing, bulkheads, heatshields, fuel leaks, etc. If it's a Have Glass 5 jet, add more time due to the 3600 coating.

On the F-35, the maintainers would experience the same issues. Hopefully experienced mechanics are leading the removal/re-install.
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