What is that TUBE at back of the B737 JET engine?!

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Have you ever noticed that there is a long thin tube protruding out of the back of the Boeing 737 jet engines? Sometimes there is smoke coing out of the tube, after the aircraft has shut down the engines. Do YOU know what that tube actually does?
I will dare to guess that you THINK that you know what it is but I also think that this video will surprise you!
In todays video we will dive deep into the oil system of the CFM56 and I will tell you about a feature of the system that not even I knew existed in this way before I started to research.
As always I would love to have your feedback about what you thought of the video as well as more questions on systems or other things you would like me to discuss.
Please leave a LIKE and a comment to the video and who knows, maybe it will be YOUR question I base my next video on.
Now! Come in to the Mentour Aviation app and discuss what You think about this! Download the app for FREE using the link below 👇
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Links partially used as sources for todays episode:
aviation.stackexchange.com/qu...
www.airliners.net/forum/viewt...
www.fzt.haw-hamburg.de/pers/S...

[@JayPatel101]

"Almost every night, we have to top up with quarts of oil" - A similar feature or requirement exists for an Audi as well. Your videos are as always fantastic and I learn a lot each time!

[@MultiClittle]

i keep seeing audi comments like this, and i love it ;)

[@robert_iadanza]

Same for older Porsche engines!

[@aapbehr]

I have been a jet engine mechanic and instructor for 11 years. You presented this information fantastically. I love that you took the time to learn a complex system like this. It will make you an even better pilot and instructor as well. Side note, it means a lot that you are interested in this. Most pilots don’t know or care about the deep in the weeds details like this.

[@marhawkman303]

hahah, yeah, at 1:25 I was like "because you're a pilot and not a mechanic." :D He is trained in how to use the aircraft safely. Knowing how to repair it and service it is optional. As someone who is neither, the more i read about how avionics work, the more I think that you're not gonna find a single person on Earth who can do all the mechanical stuff in these planes.

[@Xamry]

I know!! I love him. His enthusiasm is contagious, too. I am watching stuff like this because I have zero understanding of tech and mechanical stuff but my dad is a pilot and knows some mech stuff. My brother is a pilot but not very technical. So I just wanna be able to meet them somewhere 😂 I’m more of a meteorology person. Gimme my weather stuff. 🤓 I can talk about that all day.

[@climber950]

When I became a flight paramedic, I had lots of questions about the aircraft for the pilots I flew with. Being flight EMS is routinely in the top 10 most dangerous jobs, I had no shame asking, I just made sure to ask at appropriate times. Although the time I asked my favorite pilot who was a former Air Assault pilot “how do I fire the missiles?!?” I got some pretty funny looks. I’m no engineer but I find this stuff fascinating.

[@malice6081]

Yeah, it’s good to know how things work. For instance in modern locomotives it’s good to know how things work do you could maybe fox it temporarily until you get it to the depot

[@pissarozzz7498]

I am not a pilot but a future cc, and I am flabbergasted by the amazing engineering needed to build an A/C. It is truly wonderful how we have come from riding horses to flying. The engine engineering its specially interesting. I can only say that I am looking forward for the Airbus hydrogen engines and to see how would they work.

[@howward4071]

He took two of those cones, spray painted them black and hung them over his dining room table.

[@johnbutrovich2056]

Never noticed that.

[@Quasihamster]

Theft protection for the plane!

[@Greippi10]

hue hue

[@jochen_schueller]

rofl

[@VARITHMS]

He's building a plane one piece at a time. A Johnny Cash plan

[@joeldobler3696]

As additional information from a testcell operator: The cfm56-7b (all ratings) uses about 0.3 quarts per flight hour. If you crank the engine (no lightup, just starter engagement) it uses even more. In the end after 3h runtime there is about 0.2 quarts in the centerbody (inner tube) and if the exhaust is still hot from operation it "burns" up and it stinks alot😅 Sidenote: on the old PW4000 series engines you dont have this problem because the deoiler operates at much higher rpm's. Furthermore the higher oil pressure on p&w's helps to prevent this problem Thank you peter for this interessing topic

[@mvonsmallhausen3221]

Good to know, thanks for sharing.

[@itsnaveenn]

Thank you for telling

[@jeremyduncan3654]

Best comment. I bet you would have had fun in TWA’s 1011 engine shop at LAX...

[@joeldobler3696]

@@jeremyduncan3654 i work in zurich but during those times its hard to belive in future^^

[@COIcultist]

Laughed for a moment at the mention of Quarts. I was thinking for a second 12 quarts is quite a bit more than 12 litres but of course the reverse is true. I was thinking in terms of UK pints which amount to 20 fl oz per pint so the quart is 40 fl oz but of course we are working with US quarts where you only have 16 fl oz per pint and then 32 fl oz per quart. Then just to confuse this further both sets of fl oz are different volumes. UK quart to litre 1.137 litre Us quart to litre 0.946 litre But for the prices it's better to drink pints of beer in the UK. Then you confuse things further by measuring fuel in lbs too.

[@campusto]

As a former ramp agent, I can tell you It's a good place to dry your gloves in the winter. :D

[@campusto]

Also Airbus avionics bay exhaust makes you warm very quickly :)

[@campusto]

@Corey McDonald Yes, this. :) Also, where ever you stick your gloves, make sure it's an exhaust NOT an intake :D

[@xVLADx45]

@@campusto I remember trying to write on my checklist in the rain, and everything was soaked up. So I put my hands and the paperwork under the exhaust and after 2 minutes it was completely dry :D

[@pfsantos007]

As long as you don't forget them before start up.

[@baxtercat5462]

Or by the louvred ram air exhaust doors

[@JasonB808]

I work in IT. People assume the “computer guy” knows everything there is to know about technology. But it’s so broad in scope that it’s impossible to know everything. It’s great to see Peter is still enthusiastic about learning new things about the 737 even though it’s knowledge is not necessary for his job. I don’t think I have the same enthusiasm for my line of work but the pay is decent and I am an essential worker. Still got a job.

[@josephking6515]

I was often asked how to use some software and the questioner would be astounded that I had no real idea apart from a superficial knowledge (in most cases). I installed the damn stuff but didn't necessarily use it. I found it easier to setup and configure a 1,000 user Domain than try and use more than the basics of Word or PowerPoint. My 14 year old daughter knew more about PowerPoint than I did and I would often ask her how to do x y or z with it and I was not embarrassed in the slightest by doing that. I do however wish that I had not lost my medical and could have carried on as a professional pilot. I sure do miss it and have done for the passed 29 years. 😢

[@Jdalio5]

Good point most it guys don't know shit!

[@wendymotogirl]

@@josephking6515 of course,. Most people don't understand the difference between Hardware, software, and networks. I'm pretty good at configuring hardware and networks,but software? Give me a a break. Please. Lol

[@nathan87]

@@Jdalio5 There's a difference between "not knowing everything" and "not knowing anything"...

[@The_ZeroLine]

Life itself IS about learning knew things. If more people understood this and enjoyed learning, we could have a great world.

[@KCdurt]

Hi, Mentour! I asked this question and I think I sent a picture in with it. I fuel a LOT of 73's at KMCI, so it's something I see all the time, and it's had me scratching my head for a while now. I'm also most of the way through A&P school, and I took a pic of the breather tube to school and asked several of the instructors, some of whom worked for repair/overhaul stations for the airlines for several years, and they were all stumped as well. I had searched online, but the results I kept getting assumed I was asking about the APU. I'm going to show this video to the instructors Monday! This was super, super cool! Thanks for the in-depth explanation, and have a fantastic day, Skipper!

[@Markle2k]

@Aeromecano You don't go to A&P to learn all the bits of every single aircraft and engine. The school is there to teach you the principles and then universal skills.

[@mannlypigg35]

I worked at ATS at KMCI! Worked on all sorts of 73s for southwest there!

[@kennethonalfo7312]

Nice to see a local. I’m near FOE and frequent TOP.

[@andyhill242]

I understand why as a pilot, you don't have in-depth knowledge of all an engine's, features and systems, just the ones that you need to understand the effects that they may have on the aircraft's performance. So I understand why you would need to research this question. As a very technical person myself, although not in the aerospace industry. I feel that you pitched this video just at the right level, without making it overwhelming for less technical viewers.

[@wilengle8468]

Dr Hill, Extremely well put! Petter's ability to blend the Knowledge of a LTC (Line Training Captain) with the Mechanical information from Airbus and Manuals is exactly why I'm a HUGE Supporter of his Channel as a Patron. This type of Surgical skillset of examining the situation is Extremely invaluable to a new pilot and also it can serve as a "Relaxer" to people who would gladly fly his flight knowing how much he understands complex situations that can arise!! Everyone comes away with a better understanding and that's his goal!!

[@ritag.9078]

Absolutely mind-blowing explanation and break down of the oil system. I am an aviation enthusiast but also just a housewife and mom. I was able to follow and understand 9/10’s of that explanation. That clearly shows how talented and superior Mentour is in his teaching techniques. Thank you so much for all that you share with us. All while the dogs nap peacefully by your side. AND...your Bitmoji is spot on! Love you Captain. Thank you for your dedication.

[@richardjones2151]

Peter: Never-mind thanking 'us' so much.....we are thanking *YOU* so much!!. I am a fearful-flying engineer...and your narration of this engineering subject ...(from a pilots point of view) has been GOLD!!!. You dealt with a subject (that is not your own comfort zone) so well that; I; (as an engineering expert) listened and enjoyed this video and learned knowledge from you (again).....When my finances allow it ....I will be contributing patrion to you as first priority. THANK YOU AND KEEP your amazing channel going . Best wishes to you and all family. Rich. Mid Wales. UK

[@MentourPilot]

Wow, thank you so much for your kind words Richard. It really warms my heart! See you soon, hopefully in the Patreon discord server. 👍🏻

[@nathanbasset]

Wonderful words sir.

[@marhawkman303]

@@MentourPilot funny thing about the quart/liter thing... like the difference between yards and meters... it's not that great. A liter is a bit larger, but not much. for example(and this is on a bottle I bought today) 1.25 Liters = 1.32 quarts.

[@therealajnelson]

Engineering note: air in your oil is called "emulsification" and it's a bad thing because it will reduce the viscosity (or density) of your oil. If your oil is emulsified it will not be able to lubricate the parts efficiently it can cause an engine to seize up, or bearings can fuse from excessive friction, and hydropneumatic systems can fail. This is why I love your channel Petter! Not only do you offer fantastic accident explanation videos, but you also havethr technical videos too. As a retired engineer this is right up my alley lol. Keep up the amazing work!!

[@nielsaarts1433]

Amazing video about the B737NG oil system! As an maintenance engineer i would like to add some information. The primary function of the oil in the turbofan engine is cooling of the bearings beside the obvious lubrication purposes. The bearings accumulate a lot of thermal energy via the friction and the load its carrying (small layer of oil between the bearing roller and its raceway). this thermal energy will be taken away by the oil that's why you want the oil to be taken away asap when it dropped from the bearing sinds its job is completed. The termal energy is indeed used to heat the fuel. Beside burning fuel is used to operate actuators the HMU sends fuel to the VBV VSV TBV HPTACC LPTACC and on some engines the BSV. When there is ice in the fuel it will block small passages in the system and prevent stable operation of the engine. That's why the servo fuel heater recieves the hot scavenge engine oil to heat the fuel and prevent blockages due to ice. A fun fact to add to the venting system is that the oil tank, Accessory gearbox and Transfer Gearbox are vented via the fwd sump to the tail pipe of the engine. The anti leakage valve is useful if you work on the oil system the valve prevents oil from flowing from the tank to the supply pump when there is no rear sump supply pressure. This way you don't need to drain the entire oil tank if you take lines off (the oil tank is higher than most of the system). Another function of the anti leakage valve is to prevent the oil from flowing from the tank to the engine after its been shutdown this prevents over servicing.

[@vonduus]

I know exactly how you feel about technical knowledge: I worked many years as a sound engineer, and I knew everything about my equipment - on the outside. What microphones to use, what buttons to push and what nobs to turn to get beautiful sound out of the speakers, this was my thing. What happens inside my mixers, power supplys, fx-machines and what have you, was not my specialized expertise, but the repair man's. So a very important part of my expertise was to know the phone numbers of all the repair men in the area, especially those that were willing to come and fix my stuff any time of the day. Maybe this is why I find your videos so interesting: I used to sit above the audience (passengers) on "the bridge", as we called it, where I - together with the light engineer - had total control over what happened on stage. We were metaphorically speaking the pilots of the theater, helping the actors, singers, dancers and musicians (the cabin crew) to get their art up and flying, out to the audience. And just like you, we could only do our job because we had a small army of suppliers and repair men that helped us make sure that our gear always was in working order. And just like you it was our responsibility that everything was okay, and like you we had backups of almost everything that could break down. In twenty years I only had one serious "crash", and that was when an electrical spike from outside the house ran through all my power supplies, including the backups, and killed them all, fifteen minutes before the show was to begin. Luckily I had the phone number of a colleague on another theatre who could borrow me his backup power supplies, so half an hour later we were back up flying again. One difference though: It was the stage manager who did the "captain's briefing" to the passengers/audience ("we have a technical problem, so there will be a short delay blablabla"), not me, because traditionally he is the vicecaptain of the theatre, when the director, who is the real captain, has left after opening night. But this vicecaptainship was in name only, no single person was in charge when the show was up and running. Actually it is quite fascinating to see how a troupe of performers and stage hands can do their magic without a formal leader. Anyway... Greetings from Denmark!

[@leistico]

You and I do the exact same thing. You in Denmark, me in Kansas City, MO, USA

[@revenevan11]

Thanks for sharing that, it's a very analogous position, much more similar (passengers/audience, "piloting" the theater, etc) than I would've thought! That sort of specialization is in my opinion one of the most beautiful things about modern society. Knowing how to work your gear instinctively and in such detail even when something goes wrong and how to communicate with the repair men and suppliers in emergencies or even call acquaintances who hold similar jobs is essential. Those armies of repairmen are also themselves specialists who likely feel the same way about you working your magic to run the show as you do about how they do surgery on your equipment 😁

[@rogerpearson9081]

User knowledge and fixit knowledge are sometimes a lot different. A lot less cars on the road if you had to have mechanical knowledge to drive one.

[@johnknapp952]

The inverse of that is the Technician/Repair guy that knows the inside workings of your equipment, but doesn't necessarily know the operational use of the equipment outside of being able to turn it on and making sure everything works.

[@howinteresting2]

@@johnknapp952 Hey - that's probably me and probably thousands of others now lost in the software replicas. Would've loved to be a sound engineer and now struggling with the DAW equivalent.

[@XM-qk5sh]

If you are a good teacher, when you teach you also are always learning. Your students will always ask questions that will require you to teach yourself about new or different aspects. This will increase your own expertise. That's what makes you a great teacher!!!

[@garrnk]

I'm impressed I service the oil on these aircraft daily always seen oil burning in this tube. But never knew why. Thanks for teaching this mechanic something new.

[@slagellajs]

Haha yeah I’ll I knew was that the bolts holding that cone on are ALWAYS frozen.

[@M0nK3YM4NzZLP]

Then you're a bad aircraft mechanic sorry

[@garrnk]

@@M0nK3YM4NzZLP and learning every day A&P is a liscence to learn I'm not an engineer.

[@andraslibal]

Mentour has now two dogs sleeping symmetrically at his lectures :))))

[@elmuizahmed8657]

Upgraded from one engine aircraft, oops sorry one dog couch to a 2 dogs couch.

[@funastacia]

We hope that you're doing *absolutely fantastic* too :D

[@archipilot4731]

And I hope you are also doing absolutely fantastic! You have a nice channel (even tho it is in Russian mostly, which luckily I can understand) and your positive energy is simply amazing! :D

[@funastacia]

@@archipilot4731 Hvala, Milos :)) Zivim v Slovenije, tako da mislim da se razumeva :))

[@bogdaneremin6968]

Русские вперед!

[@alexeygorshikhin4197]

Для пилотов самое то

[@bogdaneremin6968]

Alexey Gorshikhin вы про что?

[@falxonPSN]

This is a pretty fascinating deep-dive into something I never would've thought to ask. Nice work, Captain!

[@lizlovsdagmara5525]

I have been an aerospace engineer in aircraft propulsion for 35+ years. I love this stuff.

[@OGchaibhai48]

12:52 I loved that bit,- “Don't hang me for those...” then 12:53 ....!😂

[@sambolino44]

Doggos are like, "What?"

[@tomkusmierz]

Actually having a breather tube going into hot exhaust stream is good choice, because you can burn off oil mist, and improve engine emissions. Same reason crank case ventilation on piston engines is fed into the intake manifold to burn any oil mist.

[@davell9410]

Obviously Chemtrail generator. Easier to see with tin-foil help.

[@MentourPilot]

😆

[@matsv201]

Well.. it does make a trail of chemicals... so it's really not wrong.

[@micstonemic696stone]

yes, I know a man who really believe this. but it was done decades ago, and it needs to be done very low for good results on spread without it dispersing

[@quillmaurer6563]

I always find it hilarious when the chemtrail believers post pictures of "chemtrail apparatus" as "proof" of chemtrails. The photos being random aircraft parts, or once a photo of a plane full of water tanks used for weight and balance testing. Not only could I know what non-nerfarious purpose all of those things serve, I can also think of things like cropdusters, firebombers, or the planes that dumped Agent Orange over Vietnam - airplanes have been equipped to dump stuff like that, we know what said equipment looks like, and it's not what the conspiracy theory people are posting.

[@micstonemic696stone]

@j mcmann this might be true, but lots of people ask for it this way and is always understood, like the hoover, the vacuum cleaner

[@TheFreaker86]

1:15 - 1:20 that is meme material! We need a GIF of this! Hilarious reaction! 🤣

[@bobthompson4319]

Dry sump is also used in some high performance cars and other cars and on motorcycles as well for a few reasons. 1 Is the car can sit lower without the oil pan hanging low because the pan is very shallow in a dry sump on a car. The engine can ensure oil pressure during lateral G so that the pump wouldn't starve and then the oil pressure would drop and then the brass bearings would take all the pressure and grind from things like the crank shaft. Because the way these bearings on a cars engines crankshaft work is that the oil is pumped in through a small hole in the middle of the bearing and that causes it to be floating in a high pressure oil so its not touching the bearings at all and is very easy to turn. And this is why start up is what causes the most wear on the engine because there's no pressure in the oil system until the pump is going fast enough and its oil is cold and more thick and harder to pump into the small gap that the oil fills and makes the shaft float. So old cold oil is thick and hard to pump and causes the most wear to the engine on all surfaces. Why there's not a electric pump that pumps at the start so oil is there before anything happens??? And then having the mechanical pump take over after start up??? IDK probably because some vehicles like Hondas or Toyotas would almost never die. lol.

[@Martin-hj4re]

1:15 Me when I get an answer in the math question but the answer isn't in any of the multiple choices

[@mgsaviation9292]

Soo relatable!

[@CaptainBobSim]

😂 So true!!

[@revenevan11]

Omg that's perfect!!!

[@stonestreaker]

That's proper meme material, right there.

[@ChrisMelville]

MathS.

[@samama8825]

Youuuu have got a gift my friend! Thanks for working on these absolutely fantastic videos, explaining complicated things easily! I have nothing todo with flying but i love to learn new things everyday, so i hit the bell long time ago! Thanks captain!

[@antoniomaglione4101]

Good to see you, Mentour Pilot! Thanks for explaining the oil cycle in CFM56 engine of the 737 aircraft. Thanks you and regards...

[@pragmatic1111]

Thank you for sharing this pretty good explanation about the complexities of a turbine engine's oil system. Earlier in my career, I was a propulsion engineer supporting the GE F-101 and F-110 engines which actually have much in common with the GE CFM-56. The oil system is complex, but straightforward. If you're amazed by it, the high pressure turbine blades will blow your mind. They are made of some of the strongest, toughest nickel and cobalt-based superalloys known. They not only operate right at the edge of their material's tensile strength, but they do so reliably at temperatures which actually exceed the temperature at which those materials become softer and lose strength. How is that possible? Perhaps this could be the subject of your next research project and video. (Hint: search for photos of high pressure turbine blades. Note they are hollow and have rows of holes. The principle is called boundary layer cooling.)

[@LivingAviation]

The way he explains thing is next level! I would love to meet him!

[@mgsaviation9292]

Yep!

[@itsnaveenn]

Yep

[@mikepilyih6524]

Yes

[@allenorganist2011]

Same here, he’s got my full confidence

[@chomp54321]

He's an instructor, so he's supposed to be able to explain things clearly, leaving no holes, but that is not a given. What's difficult is that this is not like a classroom where he could further explain things when students have questions. To explain things so clearly in a non-interactive video takes a lot of efforts and skills. That's what make some teacher better than others. If a teacher can't disseminate information in an understandable way, a head full of knowledge does no one any good. If I were to become a pilot, I want him to be my instructor.

[@PapaG603]

Great Video the dogs just crack me up..cheers from Boston Peter

[@user-co8vc5nd7l]

So many presenters would just jump into the explaining. You acknowledged the lack of knowledge initially in a super approachable way. In IT specifically there is a crazy lack of this approach. Thanks for this

[@samlewis7989]

Thanks! I'm a retired 737 pilot and I've always wondered about this.

[@renatoigmed]

son: daddy what is that pipe that comes out behind the engine? father: it's complicated...

[@dankinlin4744]

“Problems with different units” so in other words we have a Gimli glider video coming up. Can’t wait for that one!

[@soaringvulture]

Either that or a crash into Mars video.

[@quillmaurer6563]

That's where we all immediately think whenever unit confusion comes up. I'm sure most who watch this channel are already quite familiar with that story though - I wonder if he might tell some lesser known stories, maybe even go into personal experience.

[@Carveaholic]

I worked at an CRT in Mentor Ohio (and aircraft engine repair shop) for a summer as an engineering intern. Before watching the video I'm guessing the center vent tube. I was trusted with revamping the repair program for the CVT on the CFM 56 5b engines. I'll update after the video if I was right. Edit: I was right. I did learn something new. I never knew why the tolerances were so tight on the CVT. It makes sense now that I know it actually rotates with the engine. Super cool video. Side note: If you've never had to go through the manuals from the manufacturer, the FAA, and the airline and cross compare each to make sure that if one step is included in one manual, but not the others and then make sure it's included in the final program, it is a really tedious task and I recommend writing an Excel program to do it for you. Long story short they were having issues after FPI (florescent penetrant inspection) marking the cracks and defects so that after cleaning they could still find them for weld repair or plasma spray repair. I reorganized the work flow so that they could router gouge the issues before the cleaning so that the defects would still be present. Prior to this they were using black magic marker which of course was cleaned off during the cleaning phase. Love your channel. Stay safe and healthy!

[@michaelpowers9259]

I loved this video. Your explanation was excellent, especially the introduction where you explain how pilots mainly understand how the systems interact. Nothing but admiration for this presentation.

[@fightingfalconfan]

Honestly; you could have saved everyone a good 10 minutes in telling us what the tube is in the back by just saying it's a dry sump oil vent tube for the engine. Could have skipped about how the most basic turbo fan jet engine works. But good job explaining it. A lot of people don't know the big fan in the front of these engines produces the majority of the thrust. It mostly uses the fuel to rotate that giant fan.

[@CSAGFleetz]

Well the video needs to be *atleast* 10 minutes anyways ....

[@alikadhim3256]

@@CSAGFleetz it's 8 now

[@CSAGFleetz]

@@alikadhim3256 oh yea I forgot lol

[@b737driver8]

Real pilots are always learning.

[@vanallen9453]

...Thanks ever so much for researching and answering that question..I myself was paying close attention..but was dismayed with those two puppys' total lack of interest...keep up the good work ..

[@airfoxtrot2006]

Great video Mentour it was absolutely fantastic! Its my 40th Birthday tomorrow and watching your video makes my day.

[@camillejohnson7035]

I do agree with a few comments that assume as thorough as Petter's knowledge is in this field he is not an engineer. Like myself we assume Petter knows everything especially with the 737. What is so great is his level of enthusiasm in learning what he may not know all the aspects of the engineering parts of the aircraft. That is what is enjoyable to see when he takes apart a topic to reduce to us a level of understanding whatever the topic may be in the video. As always a pleasure to watch and learn. Also, as always, a shout out to Petter's 2 companions.😊

[@Robvdh87]

That future video you mentioned, on different units of measurement that can cause confusion, must be partly about the Gimli Glider I figure. Amazing story.

[@mkp8176]

One video, three different T-Shirts... :)

[@MentourPilot]

You are the Second one who noticed!

[@mkp8176]

@@MentourPilot A true fan apparently:).

[@SiblingCreature]

@@MentourPilot To be fair, I found the subject matter so engaging I almost didn't notice this myself. Probably wouldn't have except that the first T-shirt had caught my attention for being one I was unfamiliar with, and then when you were wrapping up I noticed it had changed. I only noticed that it had changed twice when I went back through the video to see where it had changed. What surprised me though was that the dogs were almost exactly the same positions between sessions. :-)

@@MentourPilot Any specific reason for that? Did you just record on different days? Or you deliberately changed T-shirts to promote more of them?

[@jonio214]

That dog on the back of the couch....too cute!

[@benblakesley5871]

Seen the thumbnail and thought it was the jet pipe. Awesome video.

[@themaus3847]

I have been wondering this for a lot of time, thanks for telling us :D

[@MentourPilot]

Ahhh, that’s what I was hoping for! It actually surprised me when I started looking into it

[@bradwilmot5066]

Upcoming video: The Gimli Glider! (YAY!)

[@chrisschack9716]

Sounds likely enough ... unit conversion can be tricky.

[@saabysaabinsky2785]

Fantastic systems graphics...really helped understanding what is going on.

[@mattshaffer5935]

Great oil system primer! It’s an amazing system that I’ve sort of forgotten about since school. Thanks!

[@SuperGenericUser]

"I thought I knew what it was. But then I started looking into it... AND REALIZED IT'S THE CHEMTRAIL DISPENSER!" 😂

[@Quasihamster]

That reminds me of the video that Lindybeige made about muzzle brakes on tanks. Never knew what these are for. Didn't know what they are called either, so googling them wasn't easy either. One day he finally found out they're called muzzle brakes - still no clue what they were good for though. Fast forward yet another few years, and the army base nearby had an open day. Sure enough they had plenty of tanks there, including some with muzzle brakes. What they also had was the bigwig of the garrison, high-ranking general thing. And that's who he went to, if anyone knows what a muzzle brake is for, it's this guy. When he asked him, he said something very interesting. He said: "...what the hell is a muzzle brake???"

[@MentourPilot]

😂😂 Exactly!! Sometimes the people you think know everything, doesn’t

[@em1osmurf]

many years ago, worked for an admiral who, whenever confronted with a question like this would go straight to (surprise, surprise) the chief petty officer that owned that equipment and get an answer. that should have been that general's next action. "I don't know, but I know someone we can ask and get an answer!" incredible man, an old-navy 3 star admiral named Bulkeley. don't make 'em like that, anymore.

[@stufenton5399]

Muzzle brakes vent the un used gasesafter the projectile leaves the barrel. Otherwise they would go back into the crew cabin and eventualy kill the crew!

[@itsmebatman]

@@stufenton5399 No what you are thinking of is the bore evacuator or whatever it's called. The muzzle break really just diverts the gases coming out of the front end of the barrel/gun. This can be to make the muzzle flash smaller. Or it can be to divert the smoke quicker so the gunner can better see where the shell goes. There are probably more uses for it too. But it has nothing to do with gases coming out of the breach.

[@Quasihamster]

@@stufenton5399 Nope. At least that's not what he said ;)

[@HappyAchterhooker]

As a aircraft mechanic myself, even i learn new things here ;)

[@lc2962]

I recently found this channel in my KZbin feed. This is a fabulous channel. I’ve learned so much about airplane construction, engineering, flight crew (captain & first officer), cabin crew, maintenance crew, it’s fascinating. As a nervous flyer, this content settles my nervous system quite a bit. The next time I board a commercial jet, especially the 737, I’ll be a better passenger and a little less nervous as I leave the ground. Thank you for the great content.

[@cfmontolio]

That reminds me of the breather cap or PCV system on a car engine. As the oil heats up, some gets turned into a vapor. The old style breather caps on the valve covers would let this excess oil vapor vent to the atmosphere. On pollution controlled vehicles, the PCV system vents the vapor into the intake manifold, where the vapor can be burned as fuel.

[@christianchristiansen99]

I agree. I guess similar pollution control requirements have not (yet?) been mandated for aircraft, although I expect it would technically be possible to let the air/oil vapor through the jet engine combustion chamber in a similar manner.

[@flagmichael]

I had a 1967 Chevy Biscayne (cheap Impala) that went through oil like crazy. I was too young to figure out why until some lowlife stole the breather cap. I bought a new one and the oil loss went down to normal. I still get a chuckle about that!

[@onlyme112]

@@flagmichael Did you drive it to the levee?

[@Cameron1411]

Any one else notice his pillows are correct navigation lights? Red: port Green starboard. Nice touch

[@nutandboltguy3720]

I also like the brown and white throw pillows.

[@yourmomlmao9638]

@@nutandboltguy3720 lol

[@Hopeless_and_Forlorn]

So much for the inside of the tube. The outside of the cone is part of the converging nozzle that increases the speed of the existing turbine exhaust gases for increased thrust. In some early jet engines, that cone, or plug, as it was called, was controlled by an electrical motor to move forward or aft to optimize thrust in flight. The motor was controlled by the pilot. In some Korean-war era engines, ground test runs provided data to calculate optimal nozzle area. The outer, tapered exhaust tube could then be parts-selected or even physically cut back to the calculated area. I have heard that this is the origin of the term "trimming" a jet engine. The term is still used even though fuel control mechanical, electrical, and software methods long ago replaced any method so crude as cutting away part of the tailpipe to adjust engine performance.

[@martingannon132]

That was a very detailed discription of the oil system for that engine.

[@nhzxboi]

Yep, thrust going out is countered by something: bearings that exert the thrust on the load (the air-frame, eventually). There's a lot of heat and pressure in that meet and greet. Oil can be recirculated, metal can be too. But, not for long. Oil is a wonderful friend! The tube is called a draft tube in trucking industry....Emission regulations have spelled the death of the draft tube. Such emissions now must be combusted before being emitted in truck engines...no doubt, aircraft engines will follow suit...just takes time.

[@fuzzy1dk]

it is only the thrust from the fan that is exerted through a bearing, in a pure turbojet the force on the thrust bearing is close to zero

[@stefanomanfredini3660]

@@fuzzy1dk and so where the thrust is transfered from the engine to the airframe?

[@SwaFixer]

Great video. I think you able to explain the system to the laymen with enough details to understand. One neat thing about the fuel heater servo is not only to cool the oil but warm the fuel to prevent ice from forming. Another thing that might amaze most people is that we never change the engine oil. We refill enough oil to keep it fresh. The CFM 56-7b is an incredibly reliable engine.

[@giveaquestion9683]

There is another very clever thing about this system you have not mentioned. The fuel-oil heat exchanger is not only for cooling down the oil, but also for heating up the fuel. The fuel itself has to be heated up before it goes into the engine as it is not flammable at low temperatures so the heat exchanger pools double duty for both tasks.

[@jress9967]

As an old retired Flight Engineer I enjoyed your video. In the “the old days” back in the 60s and 70s pilots and flight engineers ground schools taught all systems in great detail down to the inner workings of all the components of systems. Ground schools were much longer then they are now. We would have been taught the oil system just as you presented it. Much more complicated systems on reciprocating engines and turbo props. Thanks great job!

[@randomstuff9322]

I can't believe how calm your poodles are.

[@JonGreen_UK]

Why do I suspect Gimli Glider's up next? 🙂

[@timothybradek3560]

Here's an interesting side note I learned in the Navy while aboard an LST where we had three 18 cylinder huge Alco diesel engines per port; as well, starboard main propulsion shafts required for full speed ahead (our berthing quarters directly overhead). Because petroleum never breaks down; except, when dirt and sludge is accumulated through normal engine operation, it would be very expensive and unwise to pump this dirty oil overboard. Rather, these huge engines are connected via a closed loop oil system incorporating, in our case, a DeLaval Unimatic Oil Purifier Separator Centrifuge. This allows clean pure oil to once again enter these huge engines for maximum operating efficiency. Again, my point is that petroleum never break down, if kept cleaned and maintained. I'm thinking of all that oil I discarded from the number of vehicles I've owned over the years... unbelievable! Thanks..

[@AMTMech]

I love how he recognizes the levels of mechanical knowledge. If u want I recommend TTC as an AMT school. They have everything u need to learn the mechanics behind aviation

[@makecba]

13:24 I'm guessing that upcoming video is about another famous glider 😊

[@nedredhead474]

Should include the space side of aeronautics as well, one of the apollo's blew up because of unit mix ups (or a space shuttle)

[@makecba]

@@nedredhead474 that was the Mars Climate Orbiter. A conversion error lead to a wrong orbit insertion.

Gimli Glider!

[@nedredhead474]

@@makecba yeah you're right, just plummeted to the surface

[@jamest.5001]

Can a jet fly inverted? And the oiling system still work, being a dry sump?

[@23kaushikdutta]

Of course the oil system will work.. no worries at all! The rest, though, will all go to hell, unless that is, someone thought of using the roof of the fuel tank to pump fuel!!!

[@AtulBhatia]

Fighter jets routinely do; they use something called a collector tank, that's always full (pumped under positive pressure) so that the engine fuel pumps never run dry. The oil system too runs under positive pressure; it doesn't rely on gravity.

[@souocara38able]

The ones that are designed for inverted flight can do it, but not passenger jets. Most race cars also have dry sump oil systems but like passenger planes are not designed to operate inverted. The issue is that the pressure oil pump sucks oil from the bottom of the oil tank. If the tank is inverted the pump will suck air instead of oil.

[@domesticterrorist483]

I have always wondered about that tube, I reasoned that it was too small to be part of the jet exhaust. Thanks a million for this great explaination, makes my day being an elec eng myself.

[@kajun4]

Great video! I was a crew chief on the KC-135R powered by the CFM56. Those schematics brought back memories. I had wondered why there was smoke coming out of those tubes and what the little screen covering inside was for. I also now know why each engine needed about two quarts of oil after each flight. I haven't touched a 135 in almost six years and here I am still learning about the jet!

[@devial9879]

Common misconception, but it's not actually "sometimes cooling", it's almost entirely cooling. In high power transmissions and gears up 98% of lubricant flow is used entirely for cooling components, with sufficient lubrication being achieved with only around 2% of the total oil flow

[@uknowwho3790]

Thanks for the tour of some amazing engineering!

[@ZacCongo]

Brilliant stuff. Love the way you explain such complex concepts in such a simple manner so I can understand. 😊

[@HungryGuyStories]

It's an "ah-oo-gah" horn!

[@engineergaming4295]

Hungry Guy technology connections

[@AxelC2020]

If you are really interested in the jet engines internals, look AgentJayZ channel. You'll get a perspective from a person responsible for re-building jet engines.

[@jjgutowski]

Ya! AgentJayZ is amazing!!

[@pfsantos007]

Yes, excellent channel.

[@revenevan11]

I absolutely second that recommendation! I just found that channel through a comment much like this one a week or so ago! Now I'm seeing comments like this everywhere even though I've been following aviation KZbinrs for years lol. I know there's a name for the phenomenon like this when you hear a new word everywhere after you've learned it but can't recall hearing it before then, but I can't remember the name. It also could be that his viewership has explosively grown recently so now more people are talking about the channel, but I'm too lazy to check the google stats on it rn 🤷‍♂️.

[@nhytg376tgyuu765gjmg]

revenevan11 : I think the phenomena is selective awareness.

[@chicagoman58]

Thank you!

[@davidT_1989]

Peter another fantastic video. I been wondering about that for some time. Fly safe

[@Lexcommentyoutube]

this really goes to show the point, less you know about something the more you tend to think you know. After studying aeronautical engineering for 5 years i always see topics and think I know all about it, only to realise how little i actually know.

[@sanjitdaniel4588]

12:52 ".... dont hang me on those..." Both doggies JUMP up - "who said hang??? whaaat who is hanging ??? My gaaawwwd is someone trying to hang our master ??? Are we going to hang ???..."

[@ahmadtheaviationlover1937]

This is why being an aerospace engineer is much harder to get into than being a pilot! Thou being a pilot as well is also not an easy job

[@MentourPilot]

Indeed. Engineers might have an extremely high knowledge of certain systems and components but the pilots needs overview system knowledge of everything.

[@ahmadtheaviationlover1937]

Mentour Pilot, also keep in mind sir that a good pilot is always learning 😉

[@johnp139]

Of course, every pilot isn’t rated to fly every aircraft, just like every aerospace engineer doesn’t know the details of each and every system on every aircraft...coming from an aerospace engineer.

[@versasys]

Mentour Pilot actually the AME has to have knowledge of the entire aircraft. And in the case of airlines with multiple aircraft types the AME may hold licence on multiple aircraft. At the time of my retirement I held licence on 5 active aircraft type as well as having held 3 previous type.

[@speedbird9313]

Rob Wigle Weeeeell😉The day you think you know everything on an aircraft in your type rating I think you have lost your ways a bit🙃

[@rezakhodabandeh6833]

As a physician and aviation lover, I'd say that I love you as a humble and honest great man. Thanks for your great information ! 🌹

[@Void_666]

First, good video as always! I'd just like to add couple words to what you have explained, in particular about why the air is removed from the system. I won't be going into details, because that would take a book rather than a youtube video comment, so take this as simplification. You mentioned that it's the foaming of oil/air mixture that drives the necessity for removing the air from the oil. Actually, the primary purpose of the so called vent system is to remove the air from the sumps. As you mentioned, to prevent the oil from getting out of a sump, the sump is pressurized from the outside what means that air is being pumped into the sump. Then, with a constant supply of that pressurizing air, you need to somehow remove it because otherwise internal pressure of the sump would momentarily increase to a point where pressures inside the sump and outside the sump would equalize, and there would no air flow into the sump anymore, and therefore no effective sealing. In general, the air can be removed in two ways, depending on sump configuration. Two basic types are so called vented sump and so called non-vented sump. From a vented sump, which you have actually described, some of the air (not much relative to the amount being pumped into the sump) is typically sucked with oil by scavenge pump and then expelled to ambient through deaerator, and most of the air is removed through the metioned breather (also called air-oil separator becasue this it what it does) into the center vent inside the N1 shaft (in configurations like that of CFM56), and then discharged to ambient at the back of the engine. Air from a non-vented sump is removed entirly through the scavenge pump, and then through deaerator that is located somewhere down the scavenge line. The catch is that in order to suck out both the oil and the air, the scavenge pump for a non-vented sump needs to have significantly higher scavenging capability, relative to a vented sump pump that scavenges moslty oil, and just little air. For a non-vented sump that excess capability, although significant, is still fairly reasonable to achieve because much less pressurizing air gets into a non-vented sump than into a vented sump (I'll skip why is that...). If one would like to scavenge the amount of air that gets into a vented sump, that would require a hell of a powerful scavenge pump in the first place, and would also create other problems to solve. It's maybe not that it's impossible to do it, but the cons just overweight the pros. And that's actually the beauty of jet engine engineering... Literally everything, to the smallest detail is optimized to create best possible compromise of function (on both component and system level), reliability, life, integration, weight, maintainability, cost etc, etc.

[@giovannimonchietto1863]

13:27 smells like Gimli glider

[@christopherjohnson3520]

Puppies 🐶 On 🔥 Fire! What Did You Say? I Can’t Concentrate.

[@ernestomayer6485]

Really nice video, very precise and well explained. I love this kind of technical/engineering videos. Thank you!

[@turbofanlover]

I just learned something! Thanks, Mentour! :)

[@Matt_10203]

We removed the exhaust on the CFM56 today, bolts are always extremely siezed.

[@MentourPilot]

As they should be!

[@Matt_10203]

@@MentourPilot Milwaukee impactor, and 17 busted screwbits later we finally got it off. Needless to say its a pain, but id rather it be seized than it be loose. I remember finding a loose bolt around the perimeter of the turbine/exhaust when we removed the TRs, luckily theres quite a bit of redundancy in those.

[@speedbird9313]

Matt Those are 🤬

[@NiHaoMike64]

@@Matt_10203 I thought critical parts of aerospace equipment are lockwired to stop them coming loose.

[@Matt_10203]

@@NiHaoMike64 not those. As there are so many, its pretty much irrelevant as there is such a microscopic chance of more than even 1 coming loose. Saftey wire is mostly for things that once they come loose themselves, will be a critical failure, like a filter for example. If it were to come loose itd be a serious issue where as if 1 screw out of 100 comes out its not even going make a slight difference and that might be 1 screw/bolt loose in thousands of cycles, so essentially the saftey margin is ridiculously high. Plus, technically it wasnt "loose" it was just spinning in its hole. The nut wasnt actually loose.

[@mc00094]

Where would the world be without engineers? 😎

[@superdupergrover9857]

For the car guys watching, this system is directly comparable to the PCV (positive crankcase ventilation) system in reciprocating engines. The major differences are that most car engines are wet sump, and the oil misted air is fed back into the intake (via the pcv valve and tube) to be consumed in the engine.

[@Flyby-1000]

Flame arrestors... We had a 737-300 with the CFM-56B. The plane was up on jacks, therefore the flame arrestor was much higher than normal. Usually it sits about chest level, you can't miss it. There were 3 of us chilling right behind the engine discussing our plan of attack for a maintenance task we were to do. When we broke to go get the equipment we needed, Jeff, turned around and ran right into the back of that flame arrestor with his forehead and it dropped him to his knees... His forehead had a realty deep "smile" imprinted on it...luckily, no cut or blood...He got very lucky. The sound the plane made, as it did not budge of course, was a solid thud...

[@Accumulator1]

If someone looks out the window and ask about that, I can now spend the entire flight in their fce explaining what it is.

[@tgn2502]

1:14 LOLLL

[@23kaushikdutta]

Great acting skills 😝 alternate career if the pilot thing does not work out!

[@itsnaveenn]

Bro you don't make your channel videos too technical or too lightly That's what I like in your channel Thank you Who all agree

[@MentourPilot]

That’s the sweet-spot! Thanks for your kind words!

[@itsnaveenn]

@@MentourPilot welcome Bro

[@fmphotooffice5513]

It's nice to see humility on KZbin, where most other uploaders are always completely talking out of their a**. Here a professional airline trainer investigates and LEARNS a system, then presents it to his audience, first announcing it's new to him and where this knowledge fits in his professional life. Applause!

[@OttoDeCalumnias]

Nice! This one... I'm looking forwarded to your take on: "We still have a huge problem with different Units". How on earth did the industry survive with that completely outdated "Imperial" system - measuring things with reference to body parts (feet...). ? There is still no sign that the glorious United States of America will adapt the metric system anytime soon. They are unwilling to adopt a world-wide metric system, defending a medieval and incoherent US customary system because of mental inertia which now has lasted since 1795. What is really mind-blowing is that the industry is still willing to deal with that imperial BS, and that you still have to buy a "Half inch wrench" instead of using a 12mm. And basically doubling the investment in tools you need in any workshop. Just because of US solo-arrogance.

[@martijn9568]

Few of the measurement units in the aviation industry are in imperial. Nautical Miles and Knots, for example aren't imperial and also not metric. No, they're nautical. Nautical units aren't worse than their metric counterpart, if you are using them for their intended purpose: long distance navigation. P.S. Fun Fact: The USAAF/USAF have been using celcius to measure temperature in aircraft systems since at least ww2

[@timwilson7326]

It's not the most difficult thing to get used to using both

[@OttoDeCalumnias]

@@timwilson7326 Beg to differ. What is 11/32 inch plus 17/64 minus 1.2 thou? You have to sit down and take pen and paper. These situations DO HAPPEN. How many cubic inch are in a Gallon? How many feet to a mile? How many yards to a mile? Every time you wind up with a conversion factor impossible to memorize. And you have to go and look it up because nobody can remember that conversion factor. Imperial (call it US customary, for that sake) is just hopeless to work with. Still, there are defenders of the undefendable. The US completely missed the train.

[@alandaters8547]

As a citizen of the glorious United States I do agree with you. So much inertia....

[@OttoDeCalumnias]

​@@martijn9568 Nautical miles fit into the pattern of geographical Longitude/Latitude divisions as an integer. That's their advantage. Didn't know that Celsius detail.... A klick (with a K) in military speak equals 1Km. Not sure to what extend it is used. It seems that the military is adapting metric - realizing that the chance to win improves if you don't have to bring pen/paper and a calculator to the battlefield.

[@rogerhargreaves2272]

Well, to be honest I don’t think any of us knew this. Keep safe everyone.

[@David-lh1vp]

As a mechanic I apreciate a pilot who is willing to dive into the technical manuals to further understand the jet that they are in charge of. I also think that pilot training should have a bit more detail of the different systems in it for a more confident pilot. Cheers and safe travels.

[@Blacksheep1968]

The pups suddenly shifting position at the edit spot is hilarious..... ;-)

[@saqibmudabbar]

1:15 hahuh umm meh hmmmmmm 🤔

[@PsychoKern]

That is obviously where the plane poops from, *duh*

[@athgt6630]

Love it when you get that technical. Happy landings!

[@jason41a]

@1:15 is my most favorite moment on this channel haha. love it!

[@BirgitP4r2]

You shoulda opened with “chem trails, but we don’t talk about that”.