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How does the Boeing 737 Bleed-air system work?!

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For 30 days of FREE Audible, 1 FREE book and 2 Audible originals, use this link 👉 https://www.audible.com/mentourpilot Why are Jet-engines essential in order for humans to be able to breathe in Aircraft, once they are above a certain altitude? How does the bleed-air and AC system work on an aircraft and how is it operated? These are some of the questions that will be offered in this Video. As always I would love to hear if you have more questions and what else you would like me to talk about. Send in your suggestion below or contact me inside the Mentour Aviation app! To download the app, use the links below: 📲IOS: https://appstore.com/mentouraviation 📲Android: https://play.google.com/store/apps/details?id=com.teamta.mentouraviation&hl=en_US If you want to Join my Patreon Crew, and support the channel 👇🏻 📲 https://www.patreon.com/mentourpilot Follow my life on Instagram, and get awesome cockpit pictures 👇🏻 📲 https://www.instagram.com/mentour_pilot If you are interested in Aviation NEWS, or my Blog 👇🏻 📲 https://www.mentourpilot.com/news I want to send a huge "Thank YOU!" to the channels who were featured in todays video. See the AWESOME full versions below! HD Aviation Videos (External Air starter) https://youtu.be/9ORNyy2MzKE Mentor Pilot (Emergency descend from the cockpit) https://youtu.be/yHawjB2PzK0 Pratt & Whitney (How a Jet engine works) https://youtu.be/x8DK4rM6Y90
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Text Comments (632)
D. G. (4 days ago)
Hypoxia, it happened to me in the during my training in the Navy.(Lack of OX)
LennardA320 (4 days ago)
Was that air tank at tour plane? You fly boring, no Airbus or both?
NightBlado (4 days ago)
"BUUUURD" -Bambee
degenerate boi (4 days ago)
I always thought it was coming from that grating just ahead of the fan
Mr Paul Grimm (6 days ago)
Air quality is poor on planes. Farts are recycled
littlegayfairy (6 days ago)
@Mr Paul Grimm  - That's a very interesting point that you wrote about farts being recycled. That's why I try my best to fart as much as possible when I'm flying commercial. I like to share myself with the good passengers like yourself. I fly a lot from Los Angeles to NY as well as Los Angeles to London a lot. I also fly Los Angeles to Tokyo & Shanghai. We might have been on the same flight in the past and you may have smelled my great smelling farts in the past. My farts smells like rotten meat and sulfur.
Saul Savelis (7 days ago)
they should start building two smaller windows one on top other instead of one elongated. it would increase the angle of observation and will suit any age group and body constitution
Saul Savelis (7 days ago)
not pressure but density of oxygen molecules is a culprit of death zone in the mountains
littlegayfairy (8 days ago)
@Mentour Pilot  -  It's good to hear that the Boeing 787 does not use Bleed Air to supply the air for the flight deck and passenger cabin. FYI, the Australian Civil Aviation Safety Authority (CASA) established an Expert Panel on Aircraft Air Quality (EPAAQ) in  response  to  persisting  reports  from  Australia  and  overseas  about  possible  links  between  the  contamination  of  air  supplied  to  the  aircraft  cabin from the “bleed air” and  descriptions  of  post-exposure  acute  and  chronic  symptoms from those exposed to the contamination.For some individuals (commercial aircrew), chronic ill health can result from long-term exposure to contaminated air (in some cases leading to long-term disability and forced retirement). The  organophosphate,  tri-ortho-cresyl  phosphate  (TOCP),  a  known  contaminant  of  heated  engine  oils is a causative agent, as well as several other potential contaminants, may likely play a role.
mtabernig (9 days ago)
I am surprised that you try to lead us to believe that electrical compressors is more efficient than bleed air from the engine. You need energy to compress the air regardless how you accomplish that. You ider produce the electricity from a generator on the engine then "you bleeding power from the engine. If you use an APU then you add weight and burning fuel. SO; nothing is free my friends ....Adding weight and complexity is not the way.
Mihkel Kraav (9 days ago)
Why would some plains drop cabin's pressure at all (like Boeing you are talking about)? I have noticed (flying as a passenger) that some drop it to 750psi whereas the others do not drop at all -- keep it at 1000psi?
Peter Mann (12 days ago)
If someone smoked in the lav and pitched the lite butt in the trash and it started a fire could you deploy the O2 masks and then dump the pressure to snuff out the fire?
NhatAnh0475 (12 days ago)
Now I know why it smell like fuel burn and water.
Monkey D Faris (12 days ago)
Can you make one about the electric system because I liked the way u explain it
H B (13 days ago)
All I care about is that the damn things have no leg room..
David Sheriff (14 days ago)
where's the dog?
billi996 (16 days ago)
When you say burnt bird, I think of sunday lunch and the chicken in the oven, my missus is usually quite good at setting the oven timing
billi996 (16 days ago)
Why is the captain always sat on the left seat
Bo Lenander (16 days ago)
Really miss the dogs ...
Mikosch2 (17 days ago)
Q: How does the Boeing 737 Bleed-air system work?! A: It bleeds air into the Boeing 737.
Mikosch2 (17 days ago)
Q: How does the Boeing 737 Bleed-air system work?! A: It bleeds air into the Boeing 737.
Amaroq Starwind (18 days ago)
I'm also wondering... What if we used channel wings to reduce the speed and runway distance required for take-off?
Amaroq Starwind (18 days ago)
I've been thinking about water injection for the engines. What if you replaced it with Hydrogen Peroxide injection? You'd get more cooling because it has a higher boiling point than water, and it would actually _help_ combustion rather than hinder it due to the extra oxygen atom. This means greater fuel efficiency, greater power, lower exhaust temperature and emissions, and less unburnt fuel. If you have access to a water-injected plane or know someone who does, you should give hydrogen peroxide a try!
Gonzalo C (19 days ago)
Thanks for a very informative video once again! Just one question, why do you need hot air to heat up the forward cargo bay? Thank again for your vids, I love them!
CNder77 (20 days ago)
Went on a plane for first time and because of you and your videos I felt better about going. Thanks for being the awesome pilot you are and making these videos:) Thank you
Jaystarz2000 gaming (22 days ago)
Everyone uses re filtered air by plants.
Ody (22 days ago)
Can you talk about the so called fume events?
Tim Kirkland (23 days ago)
Nice video. Can you in a future video, if you haven't already explain the way a plane is pressurized? Thanks.
windshearDK (27 days ago)
I am surprised that you say you only use external air if the bleed air is not functioning... That's far from the real life conditions especially if you fly in Europe, as you say you do. Just about every airport in Europe has strict restrictions on the use of the APU, meaning the bleed air is not available because you have to shut down the APU almost immediately after you receive ground power. most modern jetways also offer conditioned air for the arriving aircraft which, unlike that archive footage you used from South America, not troublesome at all.
Patrick Treichel (1 month ago)
Can one plane jumpstart another? So if there´s no ASU available, is it possible to transfer bleedair from an airplane with running engines to another with non functional APU?
Nelson Prendergast (1 month ago)
Closing all doors (main, side, and cargo) with the portable air conditioning running is not fun for people on board!
Brian Sulway (1 month ago)
But there's no doggie today!
Adolph Hitler (1 month ago)
Pressurized cabin with talkative passengers and screaming kids or built in oxygen bar through a mask? Uh I’ll have the oxygen mask please!
Peter Ballin (1 month ago)
Where are the doggies?
Kevin Taylor (1 month ago)
3:26 This is what makes the Boeing 787 Dreamliner unique compared to Airbus A350 and all other airliners. The Boeing 787 Dreamliner has electric pumps to pressurises the cabin which means you are not breathing carcinogenic fumes as you do on Airbus A350 with bleed air from the engines. The Boeing 787 Dreamliner flying at 45, 000 feet has a lower cabin pressure of 6, 000 feet meaning clean air and no flight lag or swollen ankles for a much more comfortable flight. Boeing 787 is much safer with a yoke on each side of the cockpit in front of each pilot allowing both pilots to clearly see what the other pilot's yoke inputs are. Airbus has had several fatal crashes where one pilot is pushing his sidestick while the other pilot is pulling his sidestick in opposite directions both at the same time.
Pradeep Nehra (1 month ago)
Hi sir Sir can u explain pneumatic system in detail with diagram
Julian Arroupe (1 month ago)
It is so nice to see you using footage from argentina in 2:22! SABE airport
BananaKing (1 month ago)
Do you ever wonder how much jet engine oil makes its way into the air conditioning system? Getting away from engine bleed air systems is probably a good idea.
5002strokeforever (1 month ago)
The air would likely be higher pressure than the oil
BananaKing (1 month ago)
The best thing about pneumatic systems is you can have leaks and never have to top it up
Ron DLH (1 month ago)
Hey! Come on, where is your dog!? It's no fun like this :P
Diego Beatrice (1 month ago)
Why are u wearing the uniform at home in your living room?
blue dolphin (1 month ago)
How do you operate the air stairs on a 737 ?
homers7777 (1 month ago)
Its official. 51 people who watched this are dick head.
Fobios TG (1 month ago)
Why not use the engine's bypass air for cabin?
Koray Gun (1 month ago)
Bcs it hasnt got enough pressure.
lokon1979 (1 month ago)
I always take my own metal water bottle. I love it when I open it after the plane had reach cruising altitude it would sound like a can of soda; not so much when my tube of lip balm (like tube of lotion in stead of lipstick like) always make a mess when it squeeze out loads of it once I unscrew the top!
Jonathan M (1 month ago)
Why don't they design the new aircraft with all the carbon fibre and high strength composites to withstand ground level pressurization at altitude? Is the cost really that much more? Imagine having a flight where the ground level pressure at the destination is input in the flight computer, and the entire flight time is spent ramping up or down to meet that pressure. Are there any currently flying aircraft with that capability for medical transport?
Fritz Dittmann (1 month ago)
What are the chances of chemical contamination coming from the compressors... I realize combustion/fuel is probably not an issue but what about oils and lubricants giving off toxic fumes?
mPky1 (2 months ago)
How does the 777 air work ? Im going to guess they have openings that get narrower and that increase in pressure increases the temp...
mPky1 (2 months ago)
If the left feeds the flight deck, what happens if the left engine & bleed source is cut ?
Mark Roberts (2 months ago)
I have the pleasure of repairing parts of the bleed air systems, great to see how you use it. 👍
Black Toof (2 months ago)
I haven't personally thanked you for collabing with Kelsey. You both deserve more! 🤟🤘
SuperVt100 (2 months ago)
I believe that the newer Boeing's (787) having much lower cruising cabin altitude. In other words, they've improved the ride.
Eli Malinsky (2 months ago)
Cooling air with air, brilliant idea!
Roland Kronqvist (2 months ago)
Can you in some video explain how the ovens used to heat up food are working?
Roland Kronqvist (2 months ago)
I don't know why I find "the smell of burnt bird" so funny. :D
D C (2 months ago)
Best Aviation content on YouTube 👊
SLKVP (2 months ago)
Thanks! I just thinkng about a 737 bleed system video looking in that DUAL BLEED amber light in Xplane 10
MrWguts (2 months ago)
I like the bird ingestion explanation; you can make the di"stink"tion of which engine it went into by where the stink shows up in the aircraft.
Dan Donna (2 months ago)
I get terrible headaches up to 4 hours, going back to Chicago, IL I'm fine going Atlanta GA chewing gum and eating some food and advile helps. when go back to Chicago,IL l
Ather Radwi (2 months ago)
Thank you for admitting the "worst" 737 ! Truth must come out somewhere 😜
Bob Bowie (2 months ago)
The *outflow valves* are pretty reliable- that was the epitaph for _Payne Stewart._
Rafael Wilks (2 months ago)
9:39 I was walking underneath a Fedex plane at a static display, and I suddenly felt a really, really strong stream of warm air. That must have been it.
Alan Crews (2 months ago)
The positive pressurization of the "tube" prevents the doors from being opened, which is why you shouldn't fear someone being able to open the doors in flight.
Alan Crews (2 months ago)
The majority of the flight is at altitude, where the air is significantly colder and devoid of humidity...
Smatie99 (2 months ago)
Why does the cabin pressure not remain at ground level pressure?
Smatie99 (2 months ago)
@Mike P Aah, i get it. Thanks!!
Mike P (2 months ago)
If there is greater continuous pressurization it would create more stress on the airframe during every pressurization cycle, and this would be harmful for the aircraft fuselage, because it can eventually cause damage to the structure. A greater continuous pressurization differential between inside and outside would also be greater risk if there happens a rapid loss of cabin pressure, because in this case there would be a much larger instantaneous pressure change.
David Longden (2 months ago)
So if there is dead bird pong everywhere, safe to assume you’ve flown balls out through a flock ? Always impressed with the sub-systems on 737s .....where is the dog, videos aren’t the same without it !
Cristi V (2 months ago)
Hi I hope you read this and hopefully make a video about it. For a short flight, under 1h or so, is it not burning more fuel to climb to cruise altitude and then quickly descend than it would burn in level flight at a lower altitude? I'm really curious about all the considerations about this matter.
Jon Fether (2 months ago)
I never understood why the cabin pressure in the aircraft isn't simply ramped (to the extent possible) from the air pressure at the departure airport to the air pressure at the arrival airport over a lengthy period of time (After the aircraft is airborne enough to allow this, of course) reducing transition strain on the people in the aircraft. My initial thought would be that as Petter states, the system is quite antiquated. My second thought would be that this would increase the rapid pressure transition in a system failure mode to a point that it might be unacceptably hazardous.
ian folan (2 months ago)
Is that why some airlines do packs off take off's so the get the best performance from the engines ?
ian folan (2 months ago)
Have you ever had to use the manual pressurization ?
Nicholas Lindquist (2 months ago)
I was at the airport recently and I saw airplanes standing at the gate why is the left engine turning
Rubén BA (2 months ago)
I heard that it is/was not advisable to eat peanuts on board as dust of them can get to the air system and lead to allergy attacks to peanut-intolerant people. Is this true or false story?
TJ Figueroa (2 months ago)
@Mentour Pilot: If the plane lands pressurized and gradually normalizes during taxi, how long does that take and do you override it for emergency deplaning, for example in a fire?
TJ Figueroa (2 months ago)
12:12 Looks like Mentour has added a 767-200 to the fleet! ...it has always bugged me that a channel mostly dedicated to the 737 has a 777 for the intro graphics. But the content is so great I give him a pass.
Etienne Le Roux (2 months ago)
It's all good and well to keep pressures at reasonable levels. But how do aircraft systems provide oxygen during and entire flight? Surely there isn't enough residual O2 in the cabin once the doors are closed to keep up with the O2 demands of hundreds of people for hours at a time? (Just to be clear, I'm not referring to the emergency masks that drop from the ceiling.)
Peder Waldenstrom (2 months ago)
One follow up question. If the air is taken from the engines is there any risk of nasty stuff coming with that air? Suck as particles from the jetfuel or whatever.
MikeWard1701 (2 months ago)
Why is cabin air intentionally so dry?
Csab (2 months ago)
I think next time im gonna fly with a proper mask!
Mike Belanger (2 months ago)
We used to call the ground ASUs (Air Start Units) "Huffers".
Justin Cui (2 months ago)
Is it true that the 787 has an electronic substitution for bleed air while the 747-8, 777X, 737MAX, A350, A380, A320NEO, & A330NEO have traditional bleeds?
Ajax Jones (2 months ago)
AIRPORTS HAS NOT TOO MUCH RUNWAYS, BUT WHY THEY CALLED ALWAYS LIKE "36B", "107C", "08D"..., LIKE THEY HAVE 100 RUNWAYS?
Ajax Jones (2 months ago)
@Mike P Fu*k!!! So simple! ))) Thank you!!!
Mike P (2 months ago)
Runways are numbered from 01 to 36, because there are 360 degrees on a compass rose. The numbers mean the direction of the runway. Runway 36 means that it points to north (360 degrees). Runway 08 means that the runway heading is 80 degrees. Runway 18 means its heading is 180 degrees (south), and so on.
CHISWELL (2 months ago)
How do pilots deal with phoning in sick if they are not well?
James Wilshaw (2 months ago)
I thought left engine first was changed on the 400 and was one of the contributors to Kegworth?
Steve d (2 months ago)
I’ve never understood how you get enough oxygen just from pressurizing
Z-ray (2 months ago)
@Mentour Pilot @Mentour/Peter Why didn't you mention at all the possibility to have a cabin fume event when engine seals deteriorate and go porous? There are more than two events per day or per 10000 flights in the world today. No mention, seriously?? Why wouldn't you explain how to flush the cabin air in those events? With no concern, no training, no SOP, when there is a cabin fume event, the response is... nothing, just land ASAP. I believe you should be more responsible and raise concerns so as to find a solution, rather than contributing to the industry's omerta...
Mentour Pilot (2 months ago)
It’s the same reason you don’t need extra oxygen on the ground. The amount of oxygen as a % of the total gas is the same at altitude, just less pressure
Helios1138 (2 months ago)
What if the outflow valves both become stuck, can the cabin be "overpressurized"?
Mentour Pilot (2 months ago)
No, there is a pressure relief valve at 9.1PSI
Z-ray (2 months ago)
@Mentour/Peter Why didn't you mention at all the possibility to have a cabin fume event when engine seals deteriorate and go porous? There is more than two events per day or per 10000 flights in the world today. No mention, seriously?? Why wouldn't you explain how to flush the cabin air in those events? With no concern, no training, no SOP, when there is a cabin fume event, the response is... nothing, just land ASAP.
Abigail Edis (2 months ago)
What happens when there are four engines? In a 747 say. Do only 2 get used and 2 not or all 4?
Petr Dvorský (2 months ago)
Regarding the temperatu settings on 737 NG... is the same on MAX? Still only hotter or colder setting or can you set the temp digitally on the MAX?
Salahdine Aissa (2 months ago)
Väldigt intressant, det känns bara tryggare att flyga för varje klipp!
PPC4 (2 months ago)
I'd like to know what you're thinking when your a passenger on a plane. Are you critiquing the flight crew? Like some people get nervous as passengers but are fine when driving.
AirCambodia HD (2 months ago)
The best pilot and i really enjoin with your video brother
David Kinney (2 months ago)
What role does the auxiliary turbine have in the air feed system?
Marius Muralis (2 months ago)
Hi, a small correction: in 737-800 cabin air heats aft cargo compartment, not forward.
dannydaw59 (2 months ago)
So that manifold takes the humidity out of the air. Why? The air is too dry in the cabin.
Josu Gambee (2 months ago)
Maybe to prevent condensation? I have no idea.
Kevy Elyod (2 months ago)
Video Request Please UpVote: Transition Level & QNH
Doug Moody (2 months ago)
2 questions: What powers the air cycle machine? Secondly, what makes the masks drop from the overhead?
hamza aoutil (2 months ago)
why they choose the 5th stage for bleed air?
bobbi mke (2 months ago)
Your videos exhibit _vast_ improvement with the additional visual aids and less onerous advertising and marketing messages. Sometimes, "Bigger Is Better". Other times, "Size Matters". Regarding advertising and marketing, "Size Matters". A mention-or-a-minute at the beginning is swallow-able, just like a brief and "skippable" advert preceeding youtube videos, but "abondoned shopping carts" are rife on the web and abondoned views, likewise.
bobbi mke (2 months ago)
13:10 ["bag of chips" at 8000 feet] ==> Hypoxia allegedly dulls brain function, heart function, digestion, vision and TASTE. Q: Do pilots pack their meals to compensate for tasteless tood at altutude? (eg. Food tastes bland at altitude because there's less sensitive sense of smell, so everything tastes bland and "Gate Gourmet" must over-season food [compared to ground level] to improve paletability. eg. Severe hypoxia produces "tunnel vision", impaired thinking and, with 15-30 seconds, unconsciousness. eg. Pilots don full-face oxygen _FIRST_ , before _ANYTHING_ else, at the SMALLEST indication of pressurization issues. Memory items, immediate response, ask questions later.
bobbi mke (2 months ago)
Irony: Air conditioning system resembles a VW "bug", but cabin pressurization resembles spacecraft. "Stieoughpied Questions", 'eh?
bobbi mke (2 months ago)
Video Suggestion: Physiological effects of elevated altitude (ie. lower oxygen availability). True Fact: Unconscious pilots rarely fare well. Passengers don't enjoy the landings, either (cf. Helios Flight 522 crash, N47BA crash)