In the Air Guard we had F-100's that used J-57 engines with afterburners. We didn't have a test cell so we had to install the engines into an F-100 to test them. Then we would tow or taxi the whole airplane minus the tail assembly out to a pad and chain it to two anchor points sunk into the ground. Then we'd fire it up. We would walk all around it while it was running. The only safety rule was to avoid standing in line with the turbine. It was amazing being that close to a running jet engine, especially while it was in afterburner.

"Like liquid thunder." That's some poetry, man!

The pace of advancement in the 1940s and 1950s was incredible. In two decades, we went from the first jet engines, to the SR-71 and Concorde. I wonder if the engineers who designed models like the Orenda and J79 had any idea or expectation that their efforts would still be relied upon in the third decade of the 21st Century? That’s a testament to brilliant design.

At the company i work, we overhaul large and small airliner engines. Fan diameters from 60 to 100 inches. The company exists more than 30 years. in this time, we tested many thousands of engines. Of course, sometimes a leak or some other small quirks happen, but never something serious. After initial startup we let the engine run for some time, and make sure everything is okay. At this stage, the cowling is still open. Then a technician puts on some safety gear (a LOT of ear protection, and safety goggles), opens a small door leading directly in the testcell and enters it (all while the engine is running on idle). He will go up to the running engine from the side. Looking for oil or fuel leaks and any other problems. He will inspect the first side, the underside. Then he will will walk underneath the fan case to the other side, and finish his inspection. I did that once on a PW 4000 100 inch, with 68000 pounds of thrust. It was amazing and frightening at the same time. Even running at ground idle such an engine produces amazing amounts of energy. You feel the power in every fiber of your body. Every single cell resonates with it. After this idle leak check the technician exits the testcell and the cowlings are closed. Then the real testing starts. (seal break in, low and high power runs, vibration survey, performance survey, takeoff run and other stuff). This procedure is really safe, if you stay away from: hot parts, the intake stream, the bypass stream and the exhaust stream. My workplace is about 200 meters away from the test cell. The testcell is well insulated, so you cant really hear the sound of an engine being tested. But if one goes to takeoff thrust, you will feel the rumbling through the floor and in the air. Humbles me every time i feel it. This is the old school way it is done. Most testcells these days have cameras installed, to do the idle leak check. But where is the fun in that :)

"Liquefied thunder" 😂 thank you my friend.

When I worked at RR, we used to say we stand behind our engines, but never beside them!

"Given 'er" - Is there a more eponymous Canadian expression for maximum effort? "Let's take that Orenda out fer' a rip dere bye and we'll giver". Love it! Great vid as always JayZ.

Nothing like anchoring 30,000 hp to the ground and letting it rip

Anything is dangerous if you don’t treat it with respect

"It's idlin' " at 4:45 sounded exactly like "it's restin'" in the Monty Python parrot sketch.

If you examine photos of old jet aircraft like the F-86 you'll see that many of them have a thin red stripe that encircles the fuselage somewhere in the rear. This indicates the location of the turbine disk, so ground crews can remain clear of it while the engine is running.

Testing both repair and overhaul and production engines is usually a very routine event, but as AgentJayZ has mentioned, development testing can be a different matter. The failure of a Olympus 22R engine, back in 1962 , is still remembered locally. The engine, destined to power the ill-fated TSR2, was slung under the belly of a Vulcan FTB, and was being run up to full power on the airfield at Filton. The LP turbine shaft failed, the turbine disc was released whole and sliced into the fuel tanks in the aircraft's wing. The fuel pooled on the ground and caught fire, destroying both the aircraft and a brand-new fire engine. The disc bowled across the airfield for several hundred yards, reportedly bouncing every 150 feet, coming to rest just a few feet short of the Bristol T188 research aircraft (which I actually saw coming in to land a few years later). I also heard another story of an engine test that was carried out by Bristol Aero Engines in a disused railway tunnel, where a turbine disc was deliberately released. The disc reportedly ran around the tunnel several times before running out of energy and falling to the floor.

Fuel flow regulators is a super interesting topic. Yes, they're all digital these days, but that's what makes the old mechanical ones so much more interesting. I see them essentially as analog mechanical computers, designed to do a specific task. Understanding how they work exactly is very interesting, another dimension of interesting is tracing their development through history, probably goes back to 18th century steam technology. Would you mind to talk more about these at some point? Thanks.

If it wasn’t for the comment section of KZfaq, we would never be told how dangerous everyday actions are by people that have never done them.

This guy understands energy *with great clarity*. So very rare. Respect.

The earth turns a little faster when AgentJayZ gooses those J-79s - WHEEEEEEEEEE!

Another great video from the boss. Thank you sir, for taking the time to makes these videos. You really help people understand what you’re doing and why you do it. Like the first stage of compression, I’m a big fan.

Always find myself back at your channel and enjoy the videos Ive missed. Thank you for taking the time.

Basically, a jet engine is built to the operation standards of an industrial diesel, not those of a car engine.

I saw a CFM-56-3 that had sucked an fiberglass and aluminum ladder into it. The test cell crew had forgotten it. Two millon dollar damage.

These videos are so cool. Been binging for a while. I have a weird phobia of...well, let’s just say “large machinery” but seeing them broken down and having their purpose explained really helps.

AgentJayZ, your humour is amazing, so well delivered. Thanks for a little bit of a chuckle in these depressing times

Of course it's not going to blow up on the stand. It's just been pulled apart and inspected in minute detail, balanced, checked and then assembled using only good parts. For a machine to fail it has to have a defect, and in many cases a pretty serious one. Given the attention to detail used in overhauling a jet engine, it's probably the least likely thing to fail during testing after a nuclear reactor. The fact that the team who put it together are perfectly happy to stand next to it whilst running shows the amount of care taken. Also, nobody panics when their plane is taking off because the engines are running at takeoff power.

People that use automotive internal combustion engines in marine applications also endure highly elevated failure issues because of extended time at higher power output levels. Excellent discussion on the principles of %power.

Something else that you could have said was that turbine engines DO fail, but it happens after much use and good/bad maintenance in the field. The engines you are testing went through a rebuild, checking and calibrating so they are in the best condition they can possibly be.

I love his last remark, that should apply to everything!

Some of us old jet engine mechanics that worked on the older jets such as the T-33 (F-80) were Leary of the blades egressing the aircraft, as you could see the patches on the empennage where it happened a few times. It is the reason most military jets had a red line painted where the turbine blade was, as it was not a spot where you wanted to hang out at. Military jet engines are trimmed (tuned) for the mission they are used for. For example, there is a peace time trim, and a war time trim for most military applications for obvious reasons, so 100% isn't always the norm. Jet engines as I knew them generally idle at 60%, so like he mentioned in the video, it is very unlike a car that idles at about 10%. Jet engines are usually not throttled about simply due to exhaust temps, but they do need to set them at less than 100% most of the time. Not sure about the light switch rational, but he was trying to make a point. There is an application where the jet is run at two speeds, idle and 100%, and that is a constant speed, with a variable pitched propeller affixed to a gearbox that is mounted on the front of the jet. So, the speed is adjusted only by the pitch of the prop, even allowing it to reverse. There are so many variations and applications of the jet engine, that it would be difficult to encapsulate all of them in one video on the dangers of working on jets, but I would say from my many hours in a test cell, that the most dangerous part is the very beginning of the start up on an engine that has been apart. It would be fuel leaks (we burned up a 2million dollar J-75), and vibration of something that is unbalanced mostly in the turbine section. We use vibration pickups to monitor this and would immediately shut down an engine that exceeded norms. In conclusion, jet engines are very safe to be around, or they wouldn't be around. In public anyways...

Jay how s you re going ? Thanks for sharing this video appreciated , now I learn more and more about jet engines on and off for about 2 years now , I work fulltime in the constructions and building industry , on my spare time specially in weekends and sometimes during the week , if I got nothing to do at home first thing pop up in my mind is you re videos , its a kind of entertainment I love to watch and learn while I m off from work or nothing to do , I always get my note book and pens ready before I start watch it , as I said before I never knew anything about jet engines but now it becoming very bright in my head , I watched other videos as well but nothing kick in my head and fired up some basic knowledge for a start and go from there like youre videos , beautiful , you never stop learning right , its for my own interests not for a career I love youre videos , very educational , my son loved it too , thank you cheers mate .

your test cell is fairly similar to the diesel engine test cells at my former employer. Thick armored glass so you can see if anything has gone wrong (fuel or oil leaks, piston flying through the engine block, etc), some sound-proofing material on the walls, lots of instrumentation, and a way to control the engine being tested. I imagine the tests were similar too... kinda fun at first, but then a bit tedious.

love it so much cant believe its been 10 years since i began following this channel

I used to think I was the only one curious about all the other (less exciting) things like the engine stands. This is awesome!

Remember the engine test cell where I was in the military. 2m of concrete as sides and floor, and then a roof of thin sheet steel, there only to keep the sun off. Input side you had a massive concrete pad to keep the airflow, and a nice chain link fence to act as debris filter around it. Output side you had a set of diffusers cast out of concrete, to direct the airflow upwards and dissipate the energy. Drive the engine in on a trailer, then attach to the slide rails there, and slide forward till you can attach to the mounting points as on the airframe, and then connect all the cables and hydraulic lines, and the fuel supply, using the locations as in the airframe. OHS came there one day, and they measured over 130dB at a point 100m away from the test cell, directly down exhaust. They were not happy with that.... It was loud for the local buildings, despite having walls that were a half metre thick reinforced concrete on all the sides. Yes it also had it's own fuel supply tanks underground, but was fed from the fuel farm on the other side of the base as well, as the pipeline was not capable of supplying 200l/m at the required pressure. Full power test for an hour or more were common.

Watched your videos a few years back and have just come across them again. Love them, sort of hypnotic and relaxing. I used to fly on lots of piston planes and early jets, Comets and 707's' as a boy, My last flight was in a Stratocruiser. The whole Jumbo thing just passed me by! Anyway very interesting videos, thanks.

Nice channel man 👍 I love the vids, u can learn a lot on this channel, great work Jay!

I seem to remember an old tool box at the Pratt & Whitney test cell that was cut in half by a runaway fan blade. They also had steel plate they put over the cell room window when they ran up new models for the first time. They may have been messing with me, the computer guy, but I loved the place. It was all kinds of awesome for an 18 year old computer nerd.

My dad at Rolls Royce used to put his hand on the engine to feel for vibration in test cells. Not alot of people can or will do that these days.

I used to measure the pursentage of used engine power driving in the town in my car. That was not the quite powerful car and the result was even less than 30%. The more poweful car the less power is used in everyday life. Those vipers and camaros hardly use 10% of their power. The overall car efficiency as a transport with internal combustion engine is 2...10%.

My motto in life," just don't be in the way."

I love the fuel controller as a great example of ‘slide rule engineering’. It’s really magnificent what they managed to accomplish in the early jet age in such a short period of time. Separately, I suppose a classic automatic transmission is also an analog computer, although much simpler.

We vacuum spin pit all of our impellers and turbine disks with big air motors to spin it at 1.5 times their max RPM they would ever run in the engine before the governor would shut down the engine...New or rebuilt in Axial compressors and impellers. So if the maximum RPM in the engine is 42,000 RPM at shutdown, we spin test them to 63,000 RPM. We want them to fail in the pit if they are going to fail at all, and not in the engine while in service. We do that with all of our engine rotating components, either APU's or Propulsion. Just the facilities to spin stuff costs an incredible amount of money. Last cost was quoted at 2 million dollars for us to build another vacuum overspeed pit from scratch.

Dear Agent jayZ, Love your stuff, just an old printer from down under, but have learnt SO MUCH, from you. Hope you & yours are safe and well. Thank you. Les

Other than looking like it might be dangerous because most people don't know jack all about unusual devices, anything can be dangerous with context. People walk all the time without issue, but the moment they decide to do so with a phone in their hand and attempt to challenge physics by stepping out in front of a bus...

You're the best teacher ever.

This is great stuff, thanks for showing your testing room.

Turbine disc failures, when they go they go! eg, QF32 on the A380. Passengers were very very lucky it went under them and up through the wing, and the disc severed the controls to the outboard engine lol Its just something you try not to think about but unfortunately they happen and when your times up, its up.

Love flying in a Dash-8 beside the propeller! Does not bother me in the slightest.

Great video, but one thing that's not quite right... Aeroplane manufacturers do design for turbine disc failures. They can't stop the disc from going through the structures, but the trajectory of the "high energy debris" of the disc fragments is modelled, and no "singe point of failure" can be within these zones.... i.e. Structures in those zones have to have multiple redundant load paths, and systems (electrics, hydraulics etc.) are routed to either avoid these debris hazard zones or are duplexed to ensure continued functionality.

It's a lot safer now that remote cameras are used. The manufacturers won't allow folks into the cell when engines are running these days, especially at high power settings. Unfortunately, it can hamper the investigation of leaks etc. We had a turbine disc let go once. A piece of the disc smashed through the observation window, grazed the operators head and bounced off the control room wall. The operator was severely shaken and got a transfer to detail inspection. The test cell was used for testing three different engine types. Unfortunately, the HP turbine of one of those types lined up with the observation window. The window was subsequently modified!

The glass block used to observe the engine in a test cell that was used by a major airline was 4 feet thick. The rest of the cell was reinforced concrete and they have had a major failure of the unit under test. But this is the last test before unit is mounted on an aircraft and would rather see them fail in the test cell than the aircraft.Cool stuff.

Please answer this: So why is it more efficient to use the exhaust flow to drive a big fan (Turbofan engine) than it is to just simply allow it to flow freely out of the nozzle (TurboJet engine)??

Worked on the Sabre when I was stationed in Germany, a groundcrew was doing a full run up on sabre another groundcrew made the mistake of crawling between nosewheel and intake, he was sucked into engine never survived.

AgentJayZ, @ 14:38 I am curious about the altitude sensor - acceleration module, and how it works, Also do you have to calibrate it? Furthermore, when testing do you influence it, by making it think is at another atmosphere to see if it reacts appropriately? Just wondering how it's checked for operational standards. Thanks I have had many questions I never knew I had answered by you before I though of them.

Yes, refrigerators are tested at the end of the production line. All of them are. I have worked in that industry for many years now.

Hi Jay! Good video as usual. I'm way behind.... need to spend a couple weeks catching up if I ever have enough time. We've been testing engines back to back for months. Keep up the great work!

Curious as to your pretest FOD check in the test cell and the path of intake air in those close quarters. Great videos, thanks!

Ty For Sharing this Worx of art. Awesome to see her run again. FL

LOL! Love that last bit. So many people these days seem to prefer the helmet/basement corner/lights out lifestyle these days. Especially over this sweet & sour shivers nonsense. Thanks for going over the basics of the test cell. Stuff does happen, rarely. But if you do your job correctly from the git-go, that rarely turns into an improbability.

Great video, good teaching! A big sidetrack, but a very good point you made is the fact of being designed for 100% power at 100% duty cycle! This is something i cannot drive through most peoples heads when they speak of "modern" "high tech" piston car engines being so small for their HP. Firstly, its all been done before. We always knew that more flow, rpm, or boost or all 3 make power, BUT, There's a direct relationship between power and time an engine of a certain displacement can operate period. That has to do with thermal mass and heat rejection and transfer, and unit loading. In other words how much pressure and speed is one square inch of any bearing surface absorbing? Again a direct relationship. 1/2 the speed, 2x the life, same true for loading. So 2x the surface speed, and 2x the loading even at cruise, and 1/4 the life. The only 2 things modern that has allowed this is CNC machining making a 100yr old 4 valve design practical, and having a computer that keeps the loose nut behind the wheel from blowing it up before warranty, metallurgy also plays a lesser part. I have racing, pulling, flying And heavy duty gasoline engine experience and can tell you thats why we raced the only brand of the big 3 that DIDN'T have a separate heavy duty gasoline engine department. No, its not GM. those famous early hemis and big blocks had to power tug boats and semis and irrigation pumps and some did so at 1hp/ ci with 2 4bbls hour after hour. In 13 yrs, a 440+6 had 2500+ dragslip passes, lifting the front wheels at 4860lb, with $500 invested, 40 top eliminator trophies and using it for daily transport and it was the farm truck, NO failures of anything but spark plugs! Then into 3 more cars no overhaul just bearings 1 time. A 1960 GMC 305ci V6 truck engine weighs around 1000lb to make 175hp continously compared to the weight of a 305 smallblock. Bigger thermal mass. More cooling and probably 3x the bearing area. Contrary to popular belief, thats why good heavy duty gasoline engines have SHORT strokes big bores, and huge valves with a semi lopey cam. The biggest limitation is actually compression, worse before modern fuels. Less piston travel with short stroke and less bearing speed. Make hp with rpm. Gasoline heavy duty engine Torque is Starting at lower rpms than a diesel (except Detroit 2 cycles), even worse with a turbo diesel because if you pull it down it suddenly falls out of the turbo or hasn't spooled it yet. Those gas engines drink alot of gas but run like electric motors from bottom to top. a 478 gas V6 is a 5.125" bore x 3.86" stroke with 2.3" valves and a 306deg duration aggressive mechanical cam! It will run 600,000 miles at 4,000 rpm and pull down so slow an electronic tach won't read it! It makes 254 hp. An 855ci 6cyl cummins (with about the same bore) at 240hp runs from about 1200rpm to 2100 (900rpm) and uses a turbo. The 478s peak torque is at 1400 rpm. Hp is at 4,000 (2600+ useable rpm) less gears in trans. Bearings never touch the crank only oil, i can pour any "modern oil' in any engine. So unit loading really hasn't changed alot. At some point to be reliable it has to get bigger and heavier on the outside too! But to go from NY to LA with 80,000lb even if i couldn't haul as much net, due to engine and driveline 2x the weight, if i had to feed it I'd want the Cummins! Or better yet the Detroit with an (gasp, sacrilidge!) Allison Automatic trans.

cool video! I didn't know about those throttle control automatic restrictions, nifty.

Racecars on a track, bullets on a firing range, bulls running through the streets in Pamplona... Staying out of the way is almost often the best safety measure.

You mentioned that you use propane in the test cell instead of natural gas which is used in service. Doesn't that throw out all of the fuel flow settings and mean that the fuel system needs to be re-tuned when the engine is put in service on natural gas?

Great explanation

It's only dangerous if you hold your hot dog by your fingers, or if you leave it in the exhaust stream too long. Other than that, the only danger is that your hot dog might taste a bit like burning kerosene once its cooked.

A few years back at O'Hare there was a Boeing 767 that caught fire before takeoff... no one died and the plane never even took off so I didn't really think much of it. Only a few days ago I watched a video by TheFlightChannel that showed the event... turns out that the right engine had the Stage 2 HP turbine disk break apart into two main pieces during the takeoff roll... the smaller of these pieces went through the engine, right through the wing and the fuel tank which caused the fire, out the top of the wing and then through the roof of a warehouse over half a mile away. It was very fortunate that A. this happened when the pilots could abort takeoff and B. that the pieces of the turbine missed the fuselage. If it happened just 15sec later, you would have hundreds dead... there's no way the plane would make it back with the fire. kzfaq.info/get/bejne/eqiGeM-JmqfNhX0.html

Excellent video AgentJayZ. Excellent!

I've been following these lessons but unfortunately I couldn't get a chance in one of the aircraft maintenance companies😢😢, I wish I can get a chance some day

Turbines in modern aircraft are designed to contain failures. This is why uncontained failures are big news. But to achieve this they generally use materials like kevlar to handle the stupid energy involved. Also with FADEC they tend to use software to help. Example the Trent900 on the A380 had a software change post QF32's uncontained failure (when the second spool turbine disk burst following a failure that decoupled it second spool compressor... with the insane RPM increase that would result!) from the inter that would prevent a similar disk burst by using the processing speed of the FADEC to cut the fuel flow when the turbine speed exceeded a certain RPM (which was well above normal operation but would ensure run down prior to reaching failure rpm).

Why is a turbine failure so much more damaging than a compressor failure? Are the required heat resistant materials that much heavier?

yea but what if a large bird that had just eaten a bunch of titanium bolts and flew threw the front door? then what?

Great video! I've a question, since sometimes you need to take apart the engine and then test it; all the procedures of unmounting parts are done in a different building closeby? can metallic dust be a problem for the engine? are dusty places a problem when working on jet engine? Thank you for your work!

“Yes it is, but we’re badasses and laugh danger in the face!”

Is the throttle setting on a passenger jet engined aircraft routinely anywhere between 51.23% & 95.67% on most normal flying days? & The engine is at its most efficient at around the 84.56% throttle setting? It seems that the future of all jet engine parts involves lightweight materials - ceramic matrix composites which are made in the same way as infused epoxy fibreglass boat hulls & 3d printing, just imagine that!

It has to be safer standing beside the engine on the ground than sitting beside it in a pressurized tin can at 35,000 feet.

How much "propulsion/lift/anti-thrust?" does the low pressure zone at the compressor inlet generate by "sucking" the engine forward in comparison to the thrust generated by the jet exaust

A stock engine corvette holds three world records for continuous top speed of thirty hours. Set in 1990 or so. Saw a video of it at the museum in Bowling Green. The new ones are dyno tested for much longer during development. Several days if I remember correctly

I've looked at the video clips of the failed engine on the United Airlines B.777. However, I can't make out whether there is a fan blade missing, but the fan is obviously still rotating, and there is a heavy unbalance, consistent with a fan blade off. Please also see my comment about a fan blade failure on an Air Asia A330.

The youth got confused at "Chevette", knock off of the Rabbit.

So these non FADEC engines do have nannies? Then how come that there is a warning for non FADEC aircraft to not slam the throttles forward to max power "Because you could exceed something"? A classic example is the takeoff thrust and one of the bragging rights of the Concorde back in its day was that they just smacked the thrust lever to full power for the takeoff while a DC-10 similarily had to be eased up to it.

Hey! I just found the "Orenda" plaque which was missing from one of the engines outside. It is hanging on the wall above the pegboard, next to a couple of wrenches!

AgentJayZ I never considered an example that a 10,000hp engine could use up to around 5,000hp to run the compressor blades, I'd heard a gearbox may limit some of, like Mike Patey's STOL Aircraft Draco, which had P&W PT-6 turbo-prop.........mmmmm bacon, funny fascinating......

If a turbine disk lets go, I'd imagine anyone in the control room is going to have an emotional experience and browned pants. Hopefully, that is the limit of "effects" on them.

Good video. And I've been to Fort St Johns, stopped and got fuel on my way to Alaska. There's risk in everything, impossible to eliminate it, just have to manage it best you can and it appears that you have. Every been up the road to Shepherd's Inn? One of my favorite spots.

man, id like to learn to do maintenance and rebuilds like that.. is there a school for this or somewhere to get a job in it and all?? my dream was to fly but i couldnt become a pilot for medical reasons... namely, extremely poor eyesight beyond a couple meters....

I have seen airline engines being tested for blade failure and casing contained that blade. Im sure that large fan blade contains more energy that smaller turbine blade and that turbine blades are also contained by modern airline engine casing/housing in the event of failure.

Idle on a piston engine is ~10% of max rip-em's (~600RPM, and most modern V8s start putting windows in the block at 7000). Idle on a jet is, what, 90%?

Thanks for video

Have you every seen powerturbine blades coming through the casing?

Excuse any duplication but...why would the turbine blades come flying out with more energy than compressor blades?

What makes the turbine disks more dangerous than the compressor stages? They're spinning at the same speed?

Okay how much horse power does j_49 engine has

How difficult would it be to get an RB211-22? These engines powered the L-1011, and people could hear the low hum this beauty made while starting from a mile or more away. I’d love to hear this engine start up - and watch it too. They’d smoke like crazy when the weather was cold.

One of my coworkers was telling of a time where an industrial turbine disc flew off during a mishap. I don’t remember if he was at the site during the incident or after the fact, but he said that the disc had sliced through the engine casing, then through the external engine enclosure, then through a few other building walls and ended up halfway across the power plant site.

It's funny that "Orenda" sounds a lot like Italian word "orrenda" which translates into "hideous" or "horrendous" adjective for a female noun :D

I my experience the HP compessor case is the only thing to fail. It runs the cowling and often wraps it round the slats as take off is when it is most likely to fail. I've never heard of the turbine letting go. If the fan blades fail they are restrained by the fan case.

Juan is going to be so upset that the engine decides what it's going to do

The Southwest uncontained failure that killed the woman was quite away from direction of rotation, given many factors I believe a piece of case hit window...

Sounds like a detroit diesel, wind it up till it stops screaming, shift a gear, stand on it.

Does the fuel freeze?

Silly question time - do you point the engine opposite to the Earths rotation fearing slowing/ speeding up the rotation of the Earth with the engines on full power? LoL...

Awesome test cell. Seems to me its always the uncontained compressor failure with the turbofan engines not the turbine section.