737 Fuel

[@taiyeabiodun312]

Thanks Chris, there’s no book or CBT that has given me a better understanding of the fuel system like this video. You’re amazing!!!!

[@ChrisBrady737]

Thank you Taiye, I appreciate your kind words.

[@CyberSystemOverload]

I've said this before but what a fantastic resource for anyone studying for a type rating.

[@ChrisBrady737]

Thank you, and thanks for watching

[@vikkimcdonough6153]

Or even for someone who isn't a pilot or training to be one but _is_ fascinated by the nitty-gritty details of how these planes work, like me.

[@tarkwright6511]

Chris, I keep forwarding your videos to new pilots at American Airlines. They are greatly appreciated.

[@ChrisBrady737]

Thanks for spreading the word, glad to hear that they are useful to you all.

[@PILOTCLIMB]

Amazing content! Your knowledge is impressive! Thank you!

[@ChrisBrady737]

My pleasure, thanks for watching.

[@MichaelA-cu6nv]

pilots with this level of knowledge on aircrafts are an engineers best friend, been a while since i left B737 for airbus this refreshed me well

[@ChrisBrady737]

Thank you, glad you liked the video

[@HDTokyoAviation]

Interesting story about the test flight involving the suction feeding! I had read in a manual elsewhere that the purpose of the first and second stage engine driven fuel pumps was to boost the pressure even further from what the fuel boost pumps already have done so I've always been under the impression that these pumps are more powerful and would provide reasonable pressure to the fuel in the event of a complete loss of the main fuel boost pumps. Thank you as always for your outstanding content Chris, it is always much appreciated!

[@ChrisBrady737]

In the cruise or descent or at low levels the engine drivel fuel pumps should be sufficient to deliver a decent head of fuel pressure but in the climb the effects of cavitation due to released air may, as I found, be a problem.

[@T0MaTOS]

Watched the FUEL video again. I keep learning so much every time I watch it. THANK YOU Chris!

[@ChrisBrady737]

My pleasure Jay, glad you are learning something from them.

[@SigmundAnschutz-wi2fj]

17:40 Jet fuel is ignited by an electrical spark, created by the igniters. The naked flame of a match and a spark are not comparable. The possibility of vapours being present and ignited by a static spark during refuelling is the primary risk. Thank you for this technical resource!👍👍

[@Nipun-l5d]

Said that earlier and saying that again. These videos are a boon for fresher b737 pilots like us , a hand folded thank you from India (Air India) . Thank you @chris

[@ChrisBrady737]

You are very welcome, thank you for letting me know. This is why I make these videos.

[@RedEye737]

Great presentation. Always something new that will totally surprise me. In AC/DC videos it was learning that there are 4 batteries and that battery charger is more than just a charger. The fuel system has some really cool quirks I didn't know and seeing the sensors and how they work is amazing. Love the fact there are pictures attached, thank you Captain!

[@ChrisBrady737]

Thank you. I like to try to include interesting details that are beyond the scope of the FCOMs

[@parsakuchak8167]

Thanks for your videos they are the best!! Getting the opportunity to see and visualise the different systems on the 737 is definitely helping me understand the subjects in the FCOM and my TR. Keep up the fantastic work!

[@ChrisBrady737]

You are very welcome. Thank you for your kind comments

[@telescope64]

Thanks Chris!This has been your magnum opus.Great effort,so much info and superb tips.Well done......Best wishes from Paul.

[@ChrisBrady737]

Thanks Paul, This certainly was an epic video. I had no idea when I started it that it was such a huge topic.

[@harisshahulhameed5966]

Very good presentation and lot of information on the slides. It's a big help for everyone who is working on 737. Thank you for your videos.

[@ChrisBrady737]

My pleasure, glad you found the videos helpful.

[@yams900]

Always learn a lot from your videos ! Since FS2020 was launched 2 years ago, surely you must have had more people finding your KZbin channel.

[@ChrisBrady737]

Glad to hear it but my channel has only be going for 18 months.

[@jwhizard_1822]

Very informative and professional. Your videos have helped tremendously with my AESP systems report.

[@ChrisBrady737]

That is great to hear. Good luck with your course.

[@guilhermechaves5957]

Amazing content! Just one thing about the minimum fuel temperature, I'm almost sure that all over USA they use Jet A (freezing temp of -40°). Adding the +3º C, the minimum fuel temp we go to -37ºC. Boeing recommends that you stick to the highest value until the third consecutive refueling process with Jet A1. Anyway, here in Brazil will do flights that last 7:40h (Brasília - Orlando) but I've never seen fuel temperature below -10°C. Thank you for the amazing video!

[@ChrisBrady737]

Yes you are correct about the use of Jet A and 3 refuellings, I should have mentioned it in the video. Here in Europe I have seen some very low fuel temperatures in winter when you takeoff and land in cold temperatures on a long flight.

[@luukbeers777]

Thanks again Chris! First MCC lesson today went great, partly by your excellent videos.

[@ChrisBrady737]

Well done Luuk, good luck with the rest of your course

[@ferben2114]

Excellent video, and actually, excellent channel. All of it! Thank you very much, this is what I've looking for!

[@ChrisBrady737]

Thank you for your kind comments. Please tell your colleagues

[@ferben2114]

@@ChrisBrady737 I already did! THANKS AGAIN!

[@ferben2114]

@@ChrisBrady737 and i have also spread the word about the book and web site!

[@ChrisBrady737]

You are a star - thank you

[@richsmartin]

Regarding your comment on spar valves, the start lever is mechanically connected by steel cable to the FCU on the engine which has an internal shutoff valve. This is why the engine shuts down immediately using the start levers, whereas shutting the dc spar valve with the fire handle requires the fuel to burn off if the start lever isn't moved to cut off. It can also be why an engine fire may not necessarily be stopped immediately by pulling the fire handle.

[@ChrisBrady737]

Thanks for the explanation, very helpful.

[@margaretjagvet258]

Extremely useful video! Thank you a lot for your work!

[@ChrisBrady737]

Thank you Margaret, I appreciate your kind words.

[@TheHipiska312]

Very nice voice,and a lot of knowledge! Thanks!

[@ChrisBrady737]

Thank you and thanks for watching

[@GabrielEngle]

Awesome content. Thanks again Captain!

[@ChrisBrady737]

My pleasure, glad you are enjoying the videos. Please share with your colleagues.

[@Mark-du1zj]

Great videos. I believe the fuel valve closed light on the classic is an indication of the shut off valve located at the engine mounting wing stations (wing spar). Controlled by start lever or fire switch. There is also a fuel shutoff valve on the output of the MEC controlled mechanically by the start levers only - there is no indication of this valve in the flight deck.

[@ChrisBrady737]

Thanks for the info

[@marshq400]

Many thanks Chris - super interesting and useful

[@ChrisBrady737]

Hi Dom, glad you found it useful.

[@yams900]

Excellent, very informative ! Helps me understanding PMDG 737 in FS2020 :)

[@ChrisBrady737]

Glad it helped, thanks for watching.

[@yams900]

@@ChrisBrady737 Happy you have included so many pictures from real aircrafts, piece of history covered as well!

[@T0MaTOS]

Great video Chris!

[@ChrisBrady737]

Glad you enjoyed it, thanks for watching

[@SkyteamUkraine]

Good job! Thank you Chris!👍

[@ChrisBrady737]

My pleasure, enjoy!

[@liderul11]

Again amazing info , thx Chris

[@ChrisBrady737]

You are very welcome. Thanks for watching

[@josecorreia1189]

Thank you again Captain Chris , nicelly done .

[@ChrisBrady737]

Thank you 🙏

[@dorothy5292]

Hi Chris, thank you again for the teachings. I live under the usual landing path for LBA which gets a fair share of 737s each day. By the way, there is one tiny typo, at 09:30 the quoted registration G-BNSW should be G-BSNW. Kind regards

[@ChrisBrady737]

Hi Doro, well spotted, thanks

[@ranjeetghadge4525]

Vary much useful video ! Great effort Thank sir..

[@ChrisBrady737]

You are welcome. Please tell your colleagues

[@marcbrodbeck5258]

thanks for these! Great videos

[@ChrisBrady737]

My pleasure.

[@warrengreig2583]

The extra fwd vent is for the center tank cavity. This is a 737-200 with 3 center tank bladders.

[@syedhaiderzaidi6500]

Good lessons to learn and enjoy flying...

[@ChrisBrady737]

Thank you Syed

[@Sim737Pilot]

Great video, thanks!

[@ChrisBrady737]

You're very welcome!

[@banty186]

Thanks for the great lesson sir ...

[@ChrisBrady737]

My pleasure, tell your colleagues

[@duckintheshoe]

Hello Chris. What an amazing set of videos. And your website blew my mind. Great stuff! May I ask you one question regarding the FQIS precision? I cannot seem to find this +/- 2% (NG and MAX) anywhere on the net to know where does this number comes from. Is it in the 737 AMM, maybe? I would like to know if you could point me out to the source of this information because it could be really useful. Cheers

[@ChrisBrady737]

Hi Alexandre, I have gathered then info from many sources, including the AMM. I will see if I can find the source for you.

[@duckintheshoe]

@@ChrisBrady737 great. It would be amazing if you find it. Thank you again for all the amazing material

[@ibeeadane4430]

Fantastic. Learned alot

[@ChrisBrady737]

My pleasure, thanks for watching

[@jpcoertze7668]

Thank you for your videos

[@ChrisBrady737]

My pleasure, thank you for your kind comments.

[@jpcoertze7668]

@@ChrisBrady737 upgrading soon and been a fan of your work for 7y now. Let me know if I can give advice or direction on crypto or index investing as thats what my channel is about. Thanks again

[@larrydockery7201]

love your vids chris i miss working on the l-1011 but like i said i have a big heart for the 737 she is a wonderful air plane

[@ChrisBrady737]

She is indeed a great aircraft. Beautifully engineered and a delight to fly.

[@vikkimcdonough6153]

29:46 - Could the auxiliary-tank vent's location potentially be to keep it from being affected by the disturbed air coming off the wing? Given that the wing produces considerable changes in pressure in the airflow around it (and that these changes vary considerably based on aircraft configuration and angle of attack), putting the auxiliary-tank vent behind the wing could conceivably result in situations where the pressure gradient through the vent becomes reversed and the airflow sucks fuel vapor out of the tank (which would reduce the pressure head on the fuel pumps, increase the rate at which the fuel evaporates, pose environmental concerns, and potentially become a fire/explosion hazard) rather than pushing air in. (All of this is just a guess, though.)

[@ChrisBrady737]

That is a great theory and it certainly stands up to reason. If I ever find out the reason I will post it here.

[@merchantboy]

just for info.. 32:20 both the boost pumps (for both main tanks 1 and 2) are on the aft spar for the MAX. just a tiny little thing u seemed to have missed. Your info is ofcourse correct for the NG .. this is one of the minor differences between MAX and NG Fuel systems.. amazing video otherwise. thanks

[@ChrisBrady737]

Thanks for the info, I had missed that difference.

[@jchovernut]

Yes, on the MAX, Main Tank 1 & 2 Fuel Pumps are physically located in the Center Tank; their pick-ups piped to their respective tanks. I presume this is a safety feature taking advantage of the Center Tank’s NGS Inerting feature. Possibly easier servicing as well. I had no idea the Spar Valves had their own battery packs for emergency power to close!!

[@jchovernut]

@@ChrisBrady737 I’d love to see an addendum or edit to include the MAX difference in the fuel pump locations. My airline is transitioning to MAX’s exclusively. I made all my classmates aware of your superbly informative videos; they’re helping me study for my Type Rating! ;)

[@ChrisBrady737]

Unfortunately I can’t edit a video after it has been published but I will make sure that this is mentioned in the Tech Guide and the forthcoming book i am making which is a complete compilation of all of the screens and scripts of these videos.

[@yburak1]

Thank you sir for these great videos!! Could you explain why the center tank fuel pumps low pressure lights don’t illuminate but the lights of the main tanks illuminate when the switches are OFF? If the lights of the CT are inhibited when OFF, what is the reason for that? Could you please enlighten me?

[@ChrisBrady737]

The different logic is explained in the video but essentially it is to avoid nuisance amber lights when you do not need fuel in the centre tank and therefore have the centre tank pumps off.

[@peihu2309]

Hi Chris, thank you for the impressive teaching. I'm an aerospace student doing a simulation calculation about the b737 fuel system. I wonder if u could provide some information about the electric fuel boost pumps, like the manufacturer or performance specifications. I've been stuck on finding them for a long time. I'd be appreciated your help.

[@ChrisBrady737]

Hi, I dont have any more detailed information about the fuel pumps. The manufacturer is CRANE COMPANY HYDRO-AIRE DIV 3000 WINONA AVENUE PO BOX 7722 BURBANK, CALIFORNIA 91510. Hope this helps.

[@waimea56]

Dear Chris, I have a big pb with fuel scavende pump... I don't understand why it works when the fuel main tank is half or less since the center tank is supposed to be already empty...!!What is its utility(fsp)?? Many thanks for your great teaching!

[@ChrisBrady737]

The centre tank pumps will not fully drain the tank, they will leave some residual fuel behind due to their inlet location and the aircraft body angle. The scavenge pump is used to drain any residual fuel in the centre tank.

[@waimea56]

@@ChrisBrady737 Here is why....!!Many Thanks for the explanation, very helpful...

[@rizvinnasser1383]

Awesome video Sir !! . A small doubt . Main tanks are full , center tank is about 5 tons . I have switched off left center pump . Right center still on . Cross feed closed . Now , Does the left engine feeds on left main tank or center tank and right engine from Right main tank or center tank ?

[@ChrisBrady737]

Firstly, I assume that you are talking about an NG, the system is different in the Classic. If an NG with full main tanks, the center tank scavenge pump will not operate, so that is out of the equation. On the NG the main tank pumps produce higher pressure than suction feeding so fuel for the left engine will be taken from the left wing tank. The right engine will feed from the centre tank because the centre tank pumps produce a higher pressure than the main tanks. Note that this is not the recommended way to crossfeed fuel.

[@rizvinnasser1383]

@@ChrisBrady737 Thank you so much sir . Cross-feeding to be done as per FCOM supple. in my company . Speaking of which , two further doubts regarding NGs😬. Q1) During cruise we quite often get an imbalance under 453 kgs , do we need to balance it out ? ( I understand these limits are for structural considerations and not for controllability as such - FCTM ) . Q2) In many short sectors , we often have the fuel required for flight , present as fuel on board from previous flights . In such cases , main tanks are sometimes at an Imbalance ( under 453 kgs ) , can we accept such situations ( Talking from FCOM limitation - Lateral imbalance must be scheduled to zero ) . TIA .

[@ChrisBrady737]

It is up to your company SOP in those situations. But Boeing dont require any aircrew action until 453Kg.

[@Kpaojd]

Hey, Chris. Your book is not available on the apple book store in India. Is there something you can do about it? Thanks

[@ChrisBrady737]

Hi David, I am aware of that but unfortunately I have no control over where Apple distribute their books. My apologies.

[@lkjhcasual]

видео супер. спасибо

[@ChrisBrady737]

Не за что. Расскажите, пожалуйста, своим коллегам.

[@steffenleo5997]

Good Day Capt Brady,for B737NG how much is fuel consumption Show in EICAS fuelflow kg/hours for taxing,climb and Cruise?

[@ChrisBrady737]

There are no single exact figures because there are many variables. For instance taxy fuel varies with environmental factors such as ISA deviation of temp & pressure altitude. It also varies significantly with aircraft weight and to a lesser extent on the taxyway surface and slope and engine condition.

[@bigmakskartoshechkoy6210]

Hi, Chris! Could you explain please, what exactly triggered the explosion of center tank (41:49). It's beyond me to understand, why center tank pumps are the cause of the crash

[@ChrisBrady737]

Hi BigMak, I explain it all in detail in my NGS video. Watch that first then if you need any further clarification get back to me.

[@bigmakskartoshechkoy6210]

@@ChrisBrady737 Everything is clear now! Thanks a lot for an amazing video!

[@ChrisBrady737]

My pleasure

[@steffenleo5997]

Good Morning Capt Brady, Is it possible to fly an B737NG with Autopilot Engaged/ON but the Autothrottle Off/disengaged Mode?

[@ChrisBrady737]

The guidance for this is all in the FCTM "AFDS Guidelines" it states "Autothrottle use is recommended during takeoff and climb in either automatic or manual flight. During all other phases of flight, autothrottle use is recommended only when the autopilot is engaged in CMD."

[@josecorreia1189]

Thanks!

[@ChrisBrady737]

Thank you very much for your generosity 🙏

[@josecorreia1189]

thanks to you for sharing this valuable information, best regards

[@thatdouche4436]

Where can I get one of those 737 Fuel Pump Cavitation t-shirts? 😜

[@ChrisBrady737]

😂

[@OrionRox]

Amazing video! Just one more question, exactly which No.1 pump to run when using APU on the ground? I saw some companies using the AFT pump some using the FWD pump, are there any reasons for choosing one over the other? Thanks!

[@ChrisBrady737]

It doesn't matter which pump. It is simply recommended that at least one pump in the supplying tank be on to provide positive fuel pressure and preserve the service life of the APU fuel control unit. (FCOM NP 21)

[@geometryexplainseverything4926]

Is the fuel a liquid or a gas ? As these figures quoted ....seem like alot of extra weight? N1 & N2 Nitrogen Gas ?

[@ChrisBrady737]

Fuel is kerosene, a liquid. N1 and N2 are the rotation speeds of the fan and the core of the engine respectively.

[@geometryexplainseverything4926]

@@ChrisBrady737 wow ! As a Qualified plumber these figures don't make any sense ? Liquid JETA? In wings...3900kg per wing ? JETA BEING 20% LIGHTER apprx THAN WATER so 4,680 litres....4 tonnes per wing???? Average car weighs 1.5tonnes? Are these wings no just riveted together? Aluminium? I once was sat in the AIRCRAFT while refueling was carried out. And not a sound ? Yet I could hear the baggage going in below ?......either I am miss reading your figures or something isn't right here ?????

[@ChrisBrady737]

The SG of Jet A1 depends on the temperature but is around 0.76 to 0.8

[@geometryexplainseverything4926]

@@ChrisBrady737 no sure what your point is ? Its 20% lighter than water approximately?....my point is having watched Hot water Cylinders being made soldered copper, they always add water after making them, Hydrostatic testing...adds the extra stress to the welds etc...There is no such fluid test for your Wing tanks! That's why I thought maybe it was a Gas ?

[@ChrisBrady737]

My point was only that the fuel is 0.8 of the weight of water so it is not quite as heavy as you might think, but it is still many tons of fuel in each wing. I don't know if the tanks are hydrostatically tested during manufacture, but being aircraft components they have very high standards.

[@loving_vincent]

Thanks a lot! I have some questions about fuel system. 1. Why is there only one temperature sensor? (at main tank #1) 2. Why isn't there any bypass valve at center tank?

[@ChrisBrady737]

Q1 is answered at 50:47 Q2 because if center tank bypass is required, you should still have full wing tanks.

[@炜-r4k]

whats the meaning of SG

[@ChrisBrady737]

Specific Gravity which is the density of the fuel. We use it to convert from volume to weight

[@jonessenoj6753]

Replace word fuel with AIR and makes alot more sense.!

[@ChrisBrady737]

? Can you elaborate pls

[@speedbird9313]

Dude..🤦🏻‍♂️