Boeing 747-400 Landing Gear tests

[@mrifixplanes1813]

I'm a mechanic for a pretty big airline company that has several Boeing aircraft types in its fleet.

[@ArtSkyNet]

High volume level alert! This is how you thread your viewers! Tnx!

[@AtleHazard17]

Good Stuff i dont know about you but he did not thread me at all, but he treated me nice by warning

[@plummetplum]

Thread?

[@mrifixplanes1813]

Hi 1. The lower of the two leg mounted doors. 2. Air driven pumps are powered by the pneumatic system, with engines running this air is taken from the engine compressors through a bleed duct. With engines off by either an airstart cart as done here, or by the APU. It is the same air that flows through the packs, all the ducts are connected. An air driven pump uses a turbine to drive a reciprocating piston swashplate pump. Hope that helps, please feel free to ask further questions if required.

[@mrifixplanes1813]

Hi, it's not technically ram air. "Ram air" is air forced into an inlet by forward motion. The air driven pumps are driven by the pneumatic system. Air is either "tapped off" the engine compressors (pneumatic bleed air), or delivered by the APU's air compressor, or by an air start cart connected to the pneumatic ducts, the titanium tubes that run through the aircraft. Pneumatic pressure is around 45psi. The ADPs can not operate without pneumatic system pressure. Thanks for watching!

[@ascott1980]

Absolutely fascinating. I am one of your airlines crew and find it amazing what you guys and girls do every day. Thanks for keeping me safe.

[@mrifixplanes1813]

It's British Airways. I have not had any training or have a licence for 747s, except in the cabin, although I do occasionally work on 747s under the supervision of 747 engineers. I am trained on the 777s. The hangar can contain both a 747 and a 777 and it's not uncommon for staff to work on either aircraft as required. I attended a training school to complete basic training, then BA trained me for type rating on the 777.

[@txav8tion]

good stuff! thanks for the flow and pressures.

[@MrDolemeister]

Great video MrIfixplanes. Good to see what actually happens when the gear is retracted and lowered. Keep em coming.

[@plummetplum]

What an amazing job getting close and personal to these incredible machines.

[@Xyb3rTeCh]

Your video is cool and awesome. Thumbs up for warning loud volume too.

[@mrifixplanes1813]

Cheers buddy

[@jerry150686]

Oh, you've got those very practical lowering floors! We useed to have those in CDG, but our Management decided to lock them for a while, because they thought it's too dangerous for us.... !!

[@mvmedved]

Why I'm watching this? I don't even have a plane

[@FalconX9]

Thank you for high volume alerting

[@delten-eleven1910]

Landing gear stowage are interesting solutions in design and engineering: 747, C-5, B-52, F-111 for example.

[@jurrien75]

I made a switch from base to line maintenance, sometimes miss jobs like these geartests. It’s hard work for aux pump 4 to retract a winggear.

[@booman606]

Mr fix planes two questions. 1. which gear door was changed? it looks like there are four sections two body mounted doors and two leg mounted doors. 2. Is the air driven pump driven by ram air during normal flight operations in the same ducting that air going to packs is in? And is it being powered by the same huffer that is used to air start engines? I never knew there was a ram air hydraulic pump besides the RAT. This video is so fascinating!

[@delten-eleven1910]

Always thought the outer boggies where that angle for max shock absorption on landings; actually designed to fit in the confines of the underbelly. Didn't know that the main door appendage has a pin to hold in position through rotation.

[@calvinrovinescu6166]

So for the first portion of the video they were using electric aux pump not electric demand pumps right?

[@mrifixplanes1813]

Yes, the number 4 hydraulic system AC motor driven aux pump as the number 4 system is used for the wing gear.

[@VWGTI2013]

I`m 46 and planning on going back to school for aircraft maintenance. I hope I learn this stuff. I`ve always loved planes and now I`m finally gonna learn about them. I hope I could get a job here in Chicago. I heard I might have to get a job with an MRO first to gain experience. I wanna be a line maintenance tech for Southwest. I worry about my age hurting me from getting a job. I hope not cause the school is gonna cost around $48K and I`m only getting a 2yr career certificate then getting my A&P license.

[@mrifixplanes1813]

First of all, I wish you the very best of luck. I started late too, not quite as late you though and my training wasn't quite that expensive. It was a bit of gamble but it did pay off, I have a passion for aircraft and I now do a job I don't hate, not all the time anyway, sometimes I even enjoy it :) I hope it works out for you too!

[@frankied8138]

VWGTI / Don't waste your time and money. You are too old and no one is going to hire you at that age. You are better off driving a Taxi in Chicago.

[@bagels377]

Frank D damn what a jerk.

[@optimusprimo2012]

Go for it, don't worry about it

[@booman606]

I can appreciate your concern for anonymity but it looks like it could be Delta or United if it is domestic. Did your company you work for train you on the 47? Or were you brought in with previous 47 experience?

[@shakenama]

If you're planning to fly international, chances may be good to get on a 747 as some foreign airlines still fly the "queen of the skies"....but domestic airlines phased the 747 out last year. United and Delta retired their 747 fleet in January 2018.

[@Amaaaaan1]

All planes should be fitted with manual levers on board to operate the landing gears in case the automatic system fails!

[@mrifixplanes1813]

The airliners I work on, and I suspect the majority of the rest of them too, have an "Alternate extension system". For Boeings this is usually a self contained pump package that has its own backup supply of hydraulic fluid and is powered directly from the main battery. Using a switch on the flight deck starts the pump and this feeds hydraulic fluid into actuators that are located on the gear door uplocks and gear uplocks which releases them. The landing gear then falls by gravity. The pilot can assist the locking down of the landing gear by giving the plane a little shake using the controls if they don't lock down by gravity alone. When using this system the landing gear doors do not close after the landing gear lowers. On the 777 and 787, and probably others, there is not a lot of clearance between open gear doors and the ground so I suspect there is a good chance of the gear door hitting the ground on landing but better than landing on the belly.

[@singleproppilot]

The 747 uses a manually operated, hydraulically powered gear retraction system. The gear selector lever moves cables that run back to a sector and pushrod system that moves the selector valve for the wing gear. The sector drives a second set of cables that goes to another selector valve for the body gear and nose gear. The selector valves apply hydraulic pressure to the appropriate up and or down plumbing. The wing gear and doors are driven by hydraulic system 4. The body gear, nose gear and their doors are driven by hydraulic system 1. If either hydraulic system fails, the alternate extension system will be used. It uses electric motors to mechanically open the uplocks and doors and allow the gear to fall down due to gravity. Air loads assist with pushing the gear down and then springs lock the folding links in the over-center position. In the case of an alternate extension the aircraft is landed with the gear doors open.

[@gianul]

Amazing, and this has to work in any conditions. Greatest respect for the people who made this work

[@JM-wc1jc]

Thanks for warning of high voice 👍

[@mrifixplanes1813]

;-)

[@julianmares9496]

+MrIfixplanes I'm getting my A&P license should I go for it???

[@ORFAviation]

I always wonder why the gears hang like that like they look tilted

[@mrifixplanes1813]

They wing gears are indeed tilted, to 51.7°. This is the extension/retraction position. The wing gear truck positioning actuator is always trying to tilt the gear, but obviously it can't lift the weight of the aircraft. So as soon as the aircraft lifts off the ground the gear tilts. Sensors that monitor the position of the gear are part of the air/ground system and tell the aircraft computers that it is in the air when the truck is tilted. The air/ground system is used for several systems like, landing gear retraction, thrust reverser control, auto speed-brake, auto wheel brake, and some others. This design allows for a shorter wheel well, front to rear of aircraft. The aircraft's centre fuel tank is forward of the wheel wells so is larger than if the truck was stored not-tilted. Hope that has solved your wonder :)

[@moerush04]

That is such a good idea. I never knew there were multiple ram air pumps. Thanks for the lesson! Can you sign me off for 8 hours of 47 landing gear training? Haha great video!

[@justplanecrazy5575]

Is that British airways?

[@zczvcb]

Do they use PTU while doing this massive task?

[@optimusprimo2012]

Aint nobody got time for that! Let's go with method 2

[@colinlincoln3639]

Amazing how the Boeing engineers/designers laid out the intricate landing gear system so beautifully, nearly 60years ago. With just one supercomputer. The Brain. 👍

[@MrBen527]

Great vid and info! Thanks for posting

[@mrifixplanes1813]

What I meant to imply is that both a 747 and 777 fit in the hangar at the same time.

[@crapper1]

so the jacks are there incase the pins fail and the 4 body gear retracts as well?

[@mrifixplanes1813]

Yeah, and to add some stability

[@danmclaughlin1180]

Im confused... is this a volume test??? Thanks for the pre-alert my speakers work fine.

[@Helicopterpilot16]

Are you a mechanic for Boeing?

[@jackmitchell1476]

Is it just me or has this video been edited and sped up?

[@mrifixplanes1813]

You know I've never noticed it before and it certainly wasn't my intention but during tests with the air pumps I focused on the people and it does look a little off.

[@manchesterspotter1]

Helicopterpilot16 lets just say there based at heathrow and there the flag carrier airline for the UK

[@danieljimenez8146]

Nice performance, i know they had spent hours and hours and hours, and lots of hours. To come up with that result.

[@ipetross]

Awesome footage!

[@mrifixplanes1813]

iPetroSS Glad you liked it, thanks for watching :)

[@Sterlingjob]

I thought BA would get arsey about taking videos! Wanted to take some pics of concorde but thought i better not!

[@wencyvaz3637]

Wow ..... thats amazing

[@pip12111]

Imagine if those landing gears trolled the pilots like that in flight.

[@akhtarsayed4752]

salute for technician

[@georgepayazitis961]

It's a bit to slow.

[@lakefire9985]

747 has the loudest gear retraction

[@mrifixplanes1813]

lake fire Well the retract actuator is pretty quiet as can be seen by the first retraction. The noise is really from the hydraulic pumps, electric one first, then an air driven pump which is fairly loud. .

[@lakefire9985]

MrIfixplanes the gear being locked in place is very loud..i can still remember flying on the old 747,100s back in the 80s and the loud noise of the gear locking after rotation was always interesting

[@mrifixplanes1813]

lake fire Ah, I didn't realise you meant from a passenger's perspective.

[@lakefire9985]

MrIfixplanes that is much louder than the a 330

[@hockey161616]

But why is the second test sped up? No reason to edit it and speed it up.

[@dingle849]

Jake Finnegan It's not sped up. They used a different pump.

[@slowpoke96Z28]

@Jake Finnegan You wouldnt want landing gear to move as slow as they did on the first pump. There's a maximum aircraft speed the engineers recommend for the gear to be out in open air, and if the gear retracted that slow, the aircraft would have surely passed that speed. The doors probably wouldnt make it. I'll see if I can find that speed for a 747...

[@slowpoke96Z28]

Jake Finnegan best I could find is 270 knots or 310 mph.

[@mrifixplanes1813]

Wasn't intentional, I used windows movie maker to edit the video and it obviously messed it up a bit, I hadn't even noticed.

[@slowpoke96Z28]

MrIfixplanes you didn't mess it up. Look at the people moving. They are natural speed both times. The first cycling of the gear was just slower than the second.

[@lopezzsantos2052]

Lindo demais o ser humano é muito inteligente pra criar uma máquina assim top demais

[@BudniyDen]

Хорошо, наверное

[@ranaahmad2809]

747 should have 3 pairs of tyres on each rear gears...

[@mrifixplanes1813]

Well yeah, but we cut a pair off so it would fit down the hole in the ground.

[@antoniolopezdesantaana9088]

nada mas estan jugando esos dizque mecanicos

[@SDRob01]

Air Driven FTW!!

[@alessandramacagnan5713]

Esse aí acho que é uns 380 milhões de dólares só um

[@mrifixplanes1813]

Estes foram cerca de 266 milhões de dólares quando novos

[@georgepayazitis961]

to slow.

[@itsnotjacksokeepscrolling6662]

A potatoes landing gear can go quicker than that

[@mrifixplanes1813]

Cool, didn't know that! Haven't got my type rating on the "a potato" yet.

[@itsnotjacksokeepscrolling6662]

lol

[@itsnotjacksokeepscrolling6662]

i did so shut up

[@hasanpathan4395]

👍👍

[@alessandramacagnan5713]

E se eu tivesse dinheiro compraria uns Boeing pra mim aqui em Cuiabá Brasil os outros 737 MAX 737 800 777 300 737 700 737 200 são lindos e caro milhões de dólares só um deste daí 89 milhões de dólares 98 milhões de dólares 110 milhões de dólares até 400 milhões de dólares Boeing 777