Working on a Turbojet:18 - Post-test Reworks

[@kilohertz9456]

Jay, When I worked at Crystal River Nuclear Plant in Florida we had a 9000 HP Reactor Coolant Pump shaft that sheared in a similar manner. It almost looked machined that way. Later it was determined that heat variances as the pump rotated cause a uniform stress which after 10 years operation caused the shaft to shear. Because of the shear was perfect there was no damage to the pump casing.

[@nraynaud]

but is it really a clean shear or did it grind itself clean afterwards?

[@billyost1479]

That break is built into the design. I've replaced several over the years. The groove is the point at which the AGB assembly would be compromised. So, to not destroy the gears or main drive shaft to turbine shaft... that part is the designed breaking point.

[@TheDisabledGamersChannel]

WOW that break looks as if it were cut, imagine the torque it took to break it that clean, amazing, great video as always AgentJayZ, can't wait for the next one.

[@garrettbeaver4536]

Ah the joys of working in the build stand in horizontal instead of vertical, good thing the EM takes that into account..... love the amalgamation of tools need to swap in and out for every other flat on those nuts haha keep on keeping on man

[@erichamilton9902]

Looks like what we call a "shear groove."

[@jajazver]

Thank you so much for the vibe of this episode. Really neat!

[@andrewmshowe]

You have to say "focus you fuck!"

[@hommie789]

I had a hydraulic pump with a break that was clean just like that, brand new pump and it failed when starting so it threw me through a loop for a bit as no one wants to condemn a new pump as failed but it was just like it was machined the break was so clean. I work on German stuff and looking up part numbers is hard as they change up the part numbers so much, one starter had been changed up 18 times. When you change the drive shaft do you magnify the teeth to see wear or just a naked eye visual?

[@DCabo]

Thanks For all the new terminology. I'll start using it every day.

[@pilotsimms535]

Any chance that that groove is a failsafe to avoid total destruction, like the "fuse pin" that goes in the engine mounts ?

[@billyost1479]

Pilot Simms It is.

[@AgentJayZ]

That's what I have been suggesting.

[@grahamj9101]

That groove feature in the radial drive shaft certainly looks like a shear neck to me. However, I'm trying to work out the safety philosophy for it. In a single-engined aircraft, it could only fail safe on the ground, as failure in flight would obviously mean loss of the aircraft. If it failed in flight in, say, a Phantom, then the aircraft would have a chance of landing, but a single-engined carrier landing might be risky, if the hook missed the wires. I'm familiar with accessory drive quillshafts having shear necks and I do have direct experience of the starter drive quillshaft of the Pegasus 11-61 failing during early development testing of the engine.

[@rockyrivermushrooms529]

I noticed the driveshafts for the gearbox have notches near the spline. Are they engineered to fail at that specific point to save money?

[@AgentJayZ]

I think the idea is to save the aircraft

[@3rdGenGuy]

do you think that shaft looked so perfect because it was spinning causing friction?

[@ZaphodHarkonnen]

3rd Gen Guy That was my thinking. The spinning end and stationary end would polish each other. Could be wrong of course.

[@kevyelyod1211]

@1:08 is this type of shaft joined using inertia welding?

[@SkyChaserCom]

Wow ... That's what I call a CLEAN BREAK (no pun intended)!

[@alexjones2445]

Really dig the 5 gallon water bottle dispenser, think it's a Dolphin? much easier than the gravity feed ones that you have to fight and hope they don't leak out when flipped over...have one sitting in my room at the moment.

[@drubradley8821]

AHHHH!!! wonderful!!!! I mentioned in a previous show, that I made a donation, for the great cause, and did mail out my letter to the P.O.Box, and a week or so, it was returned... If you would like, I can repackage that letter, and send it off again, to prove that I did send it out, as per the post mark ink stamping and the other ink stamp they stamped in red ink that stated "return to sender", If you wish it, I will? not a big deal if my name is in the bucket, as history has proven to me, I never win, LOL.. But either way, I am still glad to help out the cause, and I think it is really cool that you and your team put together this raffle on their behalf.

[@jw4620]

Ohhh! "Manglage"! New word and I like it!

[@nullpointer1]

Great episode! You mention that this engine's flyin' days are done but also that you need afterburner to work. What will it do in terrestrial life that needs an afterburner?

[@AgentJayZ]

I was not given that information.

[@Gkuljian]

I wonder if it exceeded it's ultimate fatigue life. I doubt it, but can't think of anything else which would explain a failure like that. It obviously broke at the place with the minimum area. No clue.

[@grahamj9101]

I wouldn't expect the radial drive shaft to have a fatigue life limit. The shear neck is an overload protection feature.

[@gregeconomeier1476]

Another quality video. Regarding the sheared aux drive shaft. It looks like the shear is in a designed weak spot as evidenced by the necking. If so, this failure may indicate a problem "downstream" that could shear the "new" shaft when brought up to operating stress. Is the fuel pump break the downstream cause of the aux drive failure? If not, maybe necessary to look farther before running up the aux drive.

[@65gtotrips]

@AgentJayZ Isn’t the break intentional in that the relief in the shaft is there incase of either shaft design limits or to break incase of too much torque❓

[@AgentJayZ]

Ever seen a broken shaft or broken bolt? They look broken. This shaft has a smooth, flat break. It looks like it's been machined and even polished. I thought that was unusual because I'd never seen anything like it before.

[@starfleetau]

the sheer point worked as intended..

[@RagedContinuum]

Have you done any vids on ultrasound inspection? I learned about it after the incessant news coverage of the Southwest engine failure

[@AgentJayZ]

No. We have done Magnetic Particle, Fluorescent Dye Penetrant, and Ultrasonic inspections, but I have not made videos about them.

[@kevyelyod1211]

@6:11 what is an aviation wrench? Is it the same as a wrench I could use on a car or machine?

[@AgentJayZ]

It's the same as a double box-end wrench, only slightly longer and thinner around the box ends. Also twice the price...

[@koreycowan1976]

You guys have a cool job!

[@Stummel01]

Is the spline part friction welded to the shaft?

[@jimsvideos7201]

I doubt it for two reasons: First I don't think the process was in use when the J79 was developed, and second because there is no reason to have different material properties in a part like that.

[@AgentJayZ]

The shaft is a one piece machined piece of beauty. Did you notice the mirror finish on the inside (...!) if the hollow(...!) shaft?

[@chrisnc1962]

Hi Jay. Apropos to the CFM fan blade you are giving away, and the recent blade failure on Southwest Airlines flight 1380, do you or any of the local jet turbine shops use X-Ray inspection techniques on blades? i.e. fan, compressor, or turbine blades.

[@AgentJayZ]

The Giveway blade is from a CF6-6. It's larger than those fitted to a CFM56.

[@RolandElliottFirstG]

That nut is what they call a pain in the neck, shaft fracture is interesting , heating and cooling with an added sheer point.

[@thomaskirschii3962]

Isn't that a shear shaft

[@oisiaa]

When are you doing the Turbofan blade drawing?

[@AgentJayZ]

In the next couple of weeks. It depends on our test cell schedule.

[@jasonmskidmore]

Are you able to say what this engine is going to be used for? Definitely got me curious now.

[@AgentJayZ]

A very useful quote from Martin Sheen in Apocalypse Now: "Sir, I am unaware of any such activity, nor would I be at liberty to discuss it if any such program did in fact exist." ... or something really close to that.

[@philbox4566]

He mentioned that it will be used for producing hot air. So my guess is that it will be a replacement for politicians in Parliament. ;)

[@stevecanyon5022]

AgentJayZ, why are the turkey feathers on a J-79-17 longer than on the -15 or earlier models?? Thanks for another great video!!

[@garym8348]

Thank you so much for your informative videos. I'm not a turbine mechanic or ANYTHING similar in the field, I'm just fascinated with the science behind how things work but I was wondering why they use 2 convergent nozzles and the outer one isn't a divergent nozzle. Wouldn't more thrust be produced if the outer nozzle was divergent? I'm not asking about the relationship of thrust compared to a rocket engine but was curious about how the Venturi effect would influence thrust. Thanks again, I haven't seen all your videos but most of them. Even the bad ass boat ones. NICE BOAT.

[@AgentJayZ]

Why? I'm not an aerodynamics engineer. Can't help you with cutting edge engineering on aerospace propulsion units, even ones designed 70 years ago.

[@nickpierpoint4116]

AgentJayZ can we have a video explaining everything on the outside of a turbofan/turbojet/turboprop, i don't know what this would be called, ancillaries i guess? The stuff bolted onto the outside of the engine, looks like a load of random shapes that i have no idea about, basically the squiggly ass bits, radiator looking thing and little cannisters, coming from a huge fan from Oxfordshire, England, UK.

[@kevyelyod1211]

@10:27 Holy C!*p even the name plate gets lock wired on! This is ultra attention to detail. Amazing. I think its time for AgentJayZ to get a head-mounted goPro and record a full maintenance session. All those in favor Like this comment. :-) I would love to watch a non stop maintenance session it would be most interesting.

[@shadowOrgon]

I was wondering recently, would there be a way to design a gas turbine so that the high pitch sounds (noise in general) were outside human hearing frequencies? As much as I love jet noise was just curious if it was possible and/or feasible

[@ASJC27]

Most of the noise comes from the jet stream itself and not the spinning assembly. The noise level is strongly dependent on the exhaust jet velocity (to the seventh power) so it can't be silenced. One thing that can be done is increasing the mixing rate of the jet with the surrounding air so that it diffuses faster and therefore creates less noise. The serrated fan nozzle on a 787 is there to do just that.

[@gtoboss600]

I have a question for you! How do you move the engines from your shop to the test cell? I would imagine some sort of trailer? I don’t believe that this has been covered yet?

[@AgentJayZ]

The shop is about 2 km from the test cell. We use engine stands strapped to a conventional car hauler trailer. The setup can be seen in some of my J47 test cell vids.

[@nijumediacom3908]

Hi sir what's the call for symmetrical power? Men's colud you plz explain

[@ShannonSmith4u2]

Isn't part of the reason it looks so clean is because one piece has been spinning, which would sand itself down?

[@jimsvideos7201]

The easiest way to tell would be to have a close enough look at them to see if the visible patterns are anything but circumferential grooves and if they match or not. It's hard to tell in the video.

[@AgentJayZ]

...ever seen a snapped axle or drive shaft? Metal mayhem. tearing and ragged edges. I was expecting that. The metal must be more uniform in these aerospace parts.

[@nemozilch9872]

Thanks for all the great videos! I understand that the thrust produced by a jet engine is due to the change in momentum of the gas passing through it. But, I've always been puzzled by what actual parts of a jet engine "feel" the thrust and transfer it to the engine mount. Is it the compressor or turbine rotor or stator blades or what?? Thanks, Bob

[@AgentJayZ]

difficult question with mysterious answer. I think it's everything behind the last stage of the turbine that "feels" thrust. Applies to basic turbojets only.

[@grahamj9101]

The whole of the engine contributes to the net thrust that it produces, but let's stick to a basic turbojet for the moment, as AgentJayZ suggests. The thrust is a summation of all the forward and rearward loads that are produced within the engine. There is no one component or section of the engine that produces the thrust, least of all the so-called thrust bearings. Keeping it fairly simple, there is a forward load on both the compressor rotor blades and stator vanes (not blades, please), as the pressure is increasing across the compressor. This load is significantly greater than the thrust of the engine. There is a rearward load on both the turbine nozzle guide vanes and rotor blades, as the pressure is reducing across them. Believe it or not, there is a rearward load across the the so-called propelling (or final) nozzle of the engine. All the forward loads, minus the rearward loads equals the net thrust that the engine produces. It's a good question, but the answer isn't really that mysterious.

[@nemozilch9872]

I think graham has it right. I did some googling and found this which seems logical and supports Graham's answer aviation.stackexchange.com/questions/33068/on-which-points-in-a-jet-engine-does-the-reaction-force-act Bob

[@grahamj9101]

The diagrammatic cross-sections of a turbojet engine (a Roll-Royce Avon) showing the forward and rearward loads through the engine have been lifted straight from R-R's publication, 'The Jet Engine'. I have my copy open at page 208 right now. I hope that I'm right: I had a career lifetime of designing gas turbine engines at R-R, industrial, marine and aero.

[@masonlewis5491]

Are new parts produced for these engines or can you only find used/reman. parts?

[@AgentJayZ]

We use serviceable parts from donor engines, and many parts are still available new. We also can manufacture a large number of parts that may no longer be available new.

[@ronaldpiper4812]

Wander if drive shaft is made to sheer. So to not trash the other parts

[@killfrog]

It realy is made to break to safe the gearbox, that s also why it's necked down at exactly the spot it broke, basically like a drive shaft key is ment to break way sooner than the drive shaft and/or connected components

[@rolandbaranov3546]

Hi AgentJayZ thanks for the video, question about your theory, if the engine was running the drive shaft was intact otherwise you lose the main fuel pump so the afterburner pump failed before or you have another problem.

[@AgentJayZ]

The shaft failed during a start attempt. And we know what the shaft is for. Thank you.

[@rolandbaranov3546]

Sorry it was not my intention to tell you what the shaft does, it is the way I reason troubleshooting a problem, in the previous video I did not see the afterburner working nor afterburner fuel fogging, yes you did mention a faulty lead so I am thinking perhaps the afterburner fuel pump was not working from the beginning.

[@grahamj9101]

You've been changing out starters that are to different standards, so is there any way that you could have overloaded that radial drive shaft, by giving it a sudden load during a start?. Does the starter drive have its own quill shaft and if so, does it have its own shear neck? Having had a mystery shear neck failure of my own on the Pegasus years ago, I'm naturally curious. I've said elsewhere that I thought it was the starter drive itself, but now I'm not so sure. It might have been the drive to another accessory: put the failing memory down to age and infirmity. Nevertheless, I do remember that the failure was ascribed to a resonance in the drive train, as a result of the sudden high initial torque from the starter.

[@KANEMUSIX]

when aircraft like the F16 use afterburner how come the flame is orange but on a very few like the B1 or the russian sukoi blue is there a reason for this

[@gyrojomo]

The bluer the flame , the more air is effectively bypassed around the main burners to supply the afterburner. Orange indicates only just enough combustion air is making it to the afterburner. Like a bunsen burner.

[@tombmaster972]

does that mean orange flames=afterburning turbojet and blue flames=afterburning turbofan?

[@joevignolor4u949]

The higher the flame temperature the more efficient and powerful the engine. The only problem is the higher the flame temperature the more thermal stress it puts on the engine components. On older engines the flames were orange because the combustion temperatures were lower. This was necessary to prevent engine components from burning up. Newer engines have better and more exotic materials in the hot section and they use lasers to make small holes in components like turbine blades that air passes through to cool the parts. Therefore you can run them much hotter and they will not damage themselves. As others here have noted to get more power while in afterburner you need more air via a fan bypass but you also need to run the flame leaner, which drives up the combustion temperature and makes the flame blue. This in turn increases power and also reduces fuel consumption.

[@EngrDan-wb5pe]

hi, you have an educating video here, i was wondering if jet engine could use petroleum instead of aviation fuel, is it possible?

[@Colaholiker]

These things can burn almost everything that is a flamable liquid. Adjustments may be necessary, and with some modification (and w/o afterburner) they can even run on natural gas or gaseous propane.

[@grahamj9101]

It's perfectly possible and has been done. Years ago, a few RAF Avro Shackleton maritime patrol aircraft (they looked like Lancasters), powered by four R-R Griffon engines, had two Viper jet engines installed in the outer nacelles behind the Griffons, for extra power on take-off. They ran on the same high octane aviation petrol/gasoline that fuelled the Griffons, rather than Avtur (the UK equivalent of Jet A1). Years later, the Pegasus engines of the Sea Harriers flying off the UK's 'Invincible' class carriers were cleared to run on the diesel fuel used by the ships' Marine Olympus gas turbine engines. However, this was for emergency use only, if the Avtur ran out. I worked on industrial and marine gas turbines at R-R IMD for the first half of my career, before I moved to R-R Bristol and aero engine design. As you will see, if you check out more of AgentJayZ's videos, the industrial engines (including R-R Avons, Speys and Olympus) that he works on run on natural gas (methane). We also had an application where an engine ran on ethane. In numerous applications, the engines were dual fuel and could change over from gas to diesel (or diesel to gas) when running at high power. A completely new fuel system is required for an engine to run on gas, of course. However, little enough modification is needed to the combustion system of a gas-fuelled engine, apart from new burners being required because of the greater volumetric fuel flow.

[@haile-hl8uv]

great video agen !!

[@williamchamberlain2263]

I've heard that the correct incantation for Canadian web/phone cams is "focus you fack"

[@sleepib]

incantation?

[@williamchamberlain2263]

Magic words producing a supernatural result.

[@sleepib]

You said incarnation, not incantation.

[@williamchamberlain2263]

Thanks: autocorrect and/or my fat fingers: edited it.

[@philbox4566]

AvE has a lot to answer to for introducing the world to Canadian slang. Mixes well with Aussie slang though. ;)

[@robc3056]

how did that break right at the radius thought that was the idea of them to stop this from happening

[@sharg0]

A late answer but you're thinking of the radius instead of a sharp corner. One of reason for making a shaft narrower like this is to introduce a breakage point when the engineers want to control where and how a break occurs. I'm guessing that is the purpose here since the break was so clean. A non-controlled break would likely be more diagonal/uneven and thus risk creating a lot of secondary issues when one half continued to rotate.

[@FabricatorFactory]

Cool. A whole lot of grinding going on. Wow. Was the drive shaft that was broken, necked down in the break area acting as a torque limiting device? Great video. Good job.

[@tinfore]

10:00 Yes!!! Our state flag!

[@GeofreySanders]

So first 'graunching' and now 'wodginess'? : D I like your words!

[@NotRealNamesAgain]

I'm new to your fascinating channel, so forgive me for the stupid question, will ya? If the engine isn't technically air-worthy because of some swapped parts from different versions of that engine, what's the engine being so nicely rebuilt and tested for? I don't yet know a lot about what you do. In your last video you said you're using the engine for *heat*? I'm intrigued. +50 points for using the word Scheisse

[@AgentJayZ]

A very useful quote from Martin Sheen in Apocalypse Now: "Sir, I am unaware of any such activity, nor would I be at liberty to discuss it if any such program did in fact exist." ... or something really close to that.

[@philbox4566]

Of course with the internets way of doing things, if an answer is not forthcoming we just make up outlandish answers of our own. My guess is that it will be used to blow hot air at those big power producing wind turbines when the wind isn't blowing. ;)

[@SuperAWaC]

good to see the driveshaft fail as designed. wanna trade something for the short piece? i don't know if i have anything that would interest you, though.

[@AgentJayZ]

The owners may want it. If not , I need one piece to make a tool. If nobody else here has a use for it, I would consider trading. I won't know for a while, so you'll have to remind me.

[@SuperAWaC]

sounds good

[@DiveTunes]

AgentJayZ--Another fantastic video, Thanks! I don't have room for a turbine blade, beautiful as it is. but I'd like to be in on the contest anyway, and I'd like to contribute to the special olympics up there. I also "wonder" about these folks that think these marvels run on air. So,... I offer to match your fuel bill for the run, up to $2,000.00 USD for donation to the special olympics and your discretionary spending on cameras, time, and our continued education.

[@jacobwaley]

tough to work on...i think you have never owned a ford?!?!?!

[@AgentJayZ]

I have owned a Mercury... Cars are harder to work on than jets. We just whine more. At least, I do...

[@dwilson1191]

Looks like a failed imperfect friction weld to me

[@SheepInACart]

Nah, its machined from a single piece, its just got a ring cut into it to provide a plane of weakness to shear in cleanly, so as to not mangle everything up when this does happen.. because afterburner fuel isn't critical to engine function. Same thing is done on automotive CV's, with the interesting note that at 125hp this pump is a simlar amount of power to a commuter hatchback, and the pre-gearing speed isn't even totally different (~7000rpm at max operating speed).

[@d.t.4523]

Hamish I've had to repair industrial gearboxes that have broken shafts, where snap ring grooves are cut into them. The narrow point is the strength limit. Cheers!

[@johnalexander2349]

Bit of superglue on that shaft and she'll be 'right.

[@GregSilverado]

surfaces look almost machined man. call it gas call it fuel who cares but we all love jet A, smells like victory unless you wear it...

[@kevyelyod1211]

After looking at KZbin SEO I wonder if you had video titles with "How to..." and "Why don't..." in the title would they attract more visitors, Humm...

[@AIM54A]

Holding your neck up like that and working on something that you can barely reach sucks. My neck hurts just watching.

[@คําฉันบุตรอุดรบุตรอุดร]

😻

[@AndreaBorgia]

Did you just say "scheiße" in German? :D

[@Ratzfourtyfour]

I think he did, lol.

[@siruck19xx]

Bei 10:25 klingt es danach. Welch Überraschung. Ist aber auch wirklich Scheiße.

[@kevyelyod1211]

@4:27 ROTFL :-)

[@RallyRat]

Land speed record!

[@BasilYohannantesla]

Could have used a rope instead of tools to tighten the whatever

[@AgentJayZ]

The best tool to use for tightening the whatever is one of those things... To loosen it, we always use one of those other things... Have you seen the best game show ever? It's called Vague! kzbin.info/www/bejne/l5-kh6KpqdSbfrc

[@douro20]

At least jet fuel isn't as flammable as gasoline.

[@panther105]

kzbin.info/www/bejne/bZ-vYmN5bKuGmKc

[@koreycowan1976]

Drip of jet fuel! Oh come on guy we both know that's air! 😂😂🤣 just kidding. But isn't it amazing what you actually see on KZbin. People will believe anything.

[@Colaholiker]

"It runs on jet fuel"??? Wait, whaddaya mean? (rofl) Just kidding! kzbin.info/www/bejne/d5uQhGWJi6yEbMUm24s You know how to swear in German, you rule! You could work a little on your pronounciation though... :-P