jetmech
Topic Author
Posts: 2322
Joined: Wed Mar 29, 2006 2:14 am

### Landing Gear Extension / Retraction Videos.

G'day Team,

I've always been most fascinated by retractable landing gear of commercial jets. I find it simply amazing that one minute you can have these huge, chunky structures hanging out in the breeze, and the next minute, nothing but the smooth contours of the belly of the aircraft. Anyway, here are some awesome videos I found on Youtube.

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

flipdewaf
Posts: 1911
Joined: Thu Jul 20, 2006 6:28 am

### RE: Landing Gear Extension / Retraction Videos.

OMG! you have no Idea how much I love you right now. I have a project hand in of Part of a design of a large freight aircraft this week and after about 6 weeks of ideas and calculations it seems that our gear is at the back of the wing box. These vids have helped so much to understand how we'll get them out of the way! Thanks JetMech.

Fred

2H4
Posts: 7960
Joined: Tue Oct 19, 2004 11:11 pm

### RE: Landing Gear Extension / Retraction Videos.

Those videos make you wonder how one could possibly stow away in a gear bay without getting killed.

2H4
Intentionally Left Blank

jetmech
Topic Author
Posts: 2322
Joined: Wed Mar 29, 2006 2:14 am

### RE: Landing Gear Extension / Retraction Videos.

 Quoting Flipdewaf (Reply 1):I have a project hand in of Part of a design of a large freight aircraft this week and after about 6 weeks of ideas and calculations it seems that our gear is at the back of the wing box.

No worries! It seems like you calculations are in agreement with those of Boeing and Airbus engineers, for pretty much every Boeing or Airbus commercial airliner I can think of has the main gear behind the wing box.

 Quoting 2H4 (Reply 2):Those videos make you wonder how one could possibly stow away in a gear bay without getting killed.

On the 747, there is actually quite a lot of extra room in the gear bays to stow away if you so wished, you just need to know where it is safe to locate yourself as the gear swings. We actually used to have a person situated inside the gear well as part of the gear swing test procedure. IIRC, his job was to observe the correct and full latching between the landing gear up-lock hooks and up-lock rollers.

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

wilax
Posts: 448
Joined: Tue Jun 18, 2002 2:39 pm

### RE: Landing Gear Extension / Retraction Videos.

I had no idea these videos existed.
I love how the A340-600 main gear levels out before it stows. This can finally put to rest the myth that gear tilts for stowage, since the tiltiest A340 gear stows like a DC-10.
Again, Thank you...

HAWK21M
Posts: 30007
Joined: Fri Jan 05, 2001 10:05 pm

### RE: Landing Gear Extension / Retraction Videos.

Great Videos Steve.
I keep browsing Youtube for Aviation related Mx videos & some are just great.
I'm Still searching unsuccessfully for that B757 Powerbackvideo though.

regds
MEL
I may not win often, but I damn well never lose!!!

micstatic
Posts: 646
Joined: Fri Jul 20, 2001 10:07 pm

### RE: Landing Gear Extension / Retraction Videos.

Does anybody have vids of flap extention/retraction?
S340,DH8,AT7,CR2/7,E135/45/170/190,319,320,717,732,733,734,735,737,738,744,752,762,763,764,772,M80,M90

HAWK21M
Posts: 30007
Joined: Fri Jan 05, 2001 10:05 pm

### RE: Landing Gear Extension / Retraction Videos.

 Quoting Micstatic (Reply 6): Does anybody have vids of flap extention/retraction?

Check regds
MEL
I may not win often, but I damn well never lose!!!

ex52tech
Posts: 553
Joined: Wed Dec 06, 2006 2:28 pm

### RE: Landing Gear Extension / Retraction Videos.

Power off, emergency extension of a DC10 gear is pretty impressive. You want to make sure that you don't have too much fuel out in the #1 and #3 tanks.

We had the wing engines and pylons on a DC10-30 off in heavy check, the riggers retracted the gear, and lifted the airplane off of the nose jack. There were 5 guys on that nose jack when they slowly lowered the gear back out. First time the engines pylons had been off in 10+ years, so there was a little learning curve involved.

Another little bit of trivia........Put a nose tire for a 742 on the inboard side of the body gear, retract the gear, and then see if the gear will come out.....It won't. Saw that happen at least twice in 20 some years.
"Saddest thing I ever witnessed....an airplane being scrapped"

jetmech
Topic Author
Posts: 2322
Joined: Wed Mar 29, 2006 2:14 am

### RE: Landing Gear Extension / Retraction Videos.

 Quoting Ex52tech (Reply 8):Put a nose tire for a 742 on the inboard side of the body gear, retract the gear, and then see if the gear will come out

That is very interesting! Are the part numbers for the nose and main gear tyres are the same for the 747 classics? I honestly can't remember. I know that 744 and 747 classic wheel assemblies are different. What exactly prevents the body gear coming back out?

 Quoting Ex52tech (Reply 8):emergency extension of a DC10 gear is pretty impressive

Is it a gravity drop system?

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

N231YE
Posts: 2620
Joined: Tue Jul 25, 2006 9:24 am

### RE: Landing Gear Extension / Retraction Videos.

How is the hydraulic system "being powered?" External Pump of some sort?...

jetmech
Topic Author
Posts: 2322
Joined: Wed Mar 29, 2006 2:14 am

### RE: Landing Gear Extension / Retraction Videos.

There are a few options available. You can certainly hook up an external cart if you like and do the gear swing that way. Some of the aircraft sound like they are using the electrical auxiliary pumps to swing the gear. When we used to do gear swings on the 747, we would usually hook up air to the ship and use #1 and #4 Air Driven Pumps (ADP's) to power the hydraulics.

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

N231YE
Posts: 2620
Joined: Tue Jul 25, 2006 9:24 am

### RE: Landing Gear Extension / Retraction Videos.

Thanks for the response. Auxiliary electric pumps make sense, but I have never even heard of air driven pumps (other than the RAT). Certainly learn something new every day around here

jetmech
Topic Author
Posts: 2322
Joined: Wed Mar 29, 2006 2:14 am

### RE: Landing Gear Extension / Retraction Videos.

ADP's may be falling out of fashion these days. I have only seen them on 747's, although I am sure other aircraft may have been fitted with these devices. It seems that electrical pumps are more popular these days.

 Quoting N231YE (Reply 12):Auxiliary electric pumps make sense, but I have never even heard of air driven pumps

On the 747, you only need hydraulic systems 1 and 4 to retract and extend the gear. With the 744's of my first employer, #1 and #4 hydraulic systems had three pumps, the Engine Driven Pump (EDP), the ADP, and an auxiliary electrical pump. #2 and #3 systems had two pumps, the EDP and an AC motor pump (electric).

The auxiliary motor pumps were only really sized for towing duties, (#4 primary brakes, #1 body gear steering and alternate brakes) and not every airline had them fitted. The ACMP's of #2 and #3 systems were able to be run continuously if the EDP failed. IIRC, 744's could be fitted with ADP's on all four hydraulic systems as an option. I also seem to remember that 747 classics had ADP's on all four hydraulic systems as standard, but I'm not sure.

You can see part of the ADP in the following pictures. The bottom of the turbine drive unit is just visible.

http://www.billzilla.org/747rearmount.jpg

The exit for the exhaust air of the ADP turbine drive unit is the small grille on the side of the strut, just near the short red line.

 View Large View MediumPhoto © Will Lanting View Large View MediumPhoto © Jid Webb

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

SFOMB67
Posts: 371
Joined: Thu Dec 08, 2005 1:20 pm

### RE: Landing Gear Extension / Retraction Videos.

 Quoting N231YE (Reply 12):Thanks for the response. Auxiliary electric pumps make sense, but I have never even heard of air driven pumps (other than the RAT). Certainly learn something new every day around here

We always used the Ctr electric pumps and the ADP when doing retractions on 767's. Adp's really put out a lot !
Not as easy as originally perceived

ex52tech
Posts: 553
Joined: Wed Dec 06, 2006 2:28 pm

### RE: Landing Gear Extension / Retraction Videos.

 Quoting JetMech (Reply 9):What exactly prevents the body gear coming back out?

The tire gets caught on the keel beam ledge. The part numbers are not the same, the nose tires are slightly bigger. When you walk over to a rack and pull a tire out, you could get the wrong one.

 Quoting JetMech (Reply 9):Is it a gravity drop system?

The emergency power off is gravity, the mains are resting on the doors, when the locks are mechanically pulled over center the airplane will bounce, as the gear pushes the doors open. I used to joke with the Hyd./ Rigging crew chief that I could not put the #2 engine reverser cowls on unless the gear swing was in progress, the joke was, that I needed the aircraft bouncing to help get the bolts in.
"Saddest thing I ever witnessed....an airplane being scrapped"

kc135topboom
Posts: 11035
Joined: Sun Jan 30, 2005 2:26 am

### RE: Landing Gear Extension / Retraction Videos.

Does anyone remember the older movies with B-707 take-offs, then they switch to the underbody scene showing the gear retraction, of a B-52?

HAWK21M
Posts: 30007
Joined: Fri Jan 05, 2001 10:05 pm

### RE: Landing Gear Extension / Retraction Videos.

 Quoting Sfomb67 (Reply 14):We always used the Ctr electric pumps and the ADP when doing retractions on 767's. Adp's really put out a lot

Checking pneumatic leaks can be tough.Especially if its the Brake system thats pneumatically operated.[F27].
regds
MEL
I may not win often, but I damn well never lose!!!

jetmech
Topic Author
Posts: 2322
Joined: Wed Mar 29, 2006 2:14 am

### RE: Landing Gear Extension / Retraction Videos.

 Quoting Ex52tech (Reply 15):The part numbers are not the same, the nose tires are slightly bigger.

Fair enough. We used to have the "serve yourself" rack system for tyres as well. I remember one of the crews accidentally fitted a 747SP wheel to a 742.

 Quoting Ex52tech (Reply 15):I used to joke with the Hyd./ Rigging crew chief that I could not put the #2 engine reverser cowls on unless the gear swing was in progress, the joke was, that I needed the aircraft bouncing to help get the bolts in.

It's amazing how a whole aircraft can start shaking due to action at one point only. One night shift, we were inspecting the flaps of a 744. The leading head got me to jiggle the outboard flaps with my hands to help look for any loose components. Within a few seconds, the entire wing was flapping up and down. All these heads then started popping out of the back of the engines as my fellow engineers looked to see what was going on.

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

Bartonsayswhat
Posts: 357
Joined: Sun Oct 28, 2007 8:42 am

### RE: Landing Gear Extension / Retraction Videos.

has anybody seen any videos of AN225/124 gear retractions (or anything else with a stupid amount of wheels)? i would love to see that

ex52tech
Posts: 553
Joined: Wed Dec 06, 2006 2:28 pm

### RE: Landing Gear Extension / Retraction Videos.

 Quoting Bartonsayswhat (Reply 19):has anybody seen any videos of AN225/124 gear retractions (or anything else with a stupid amount of wheels)? i would love to see that

We watched the crew members, probably crew chief's and load master on an AN124 one night in MSP break down a main wheel assy. with hand tools, and mount a new tire on the wheel halves. It is just not something that I would have even considered having to do, so we sat in the truck and watched. We figured that if they had to do another one that we would have to help them with some air tools.
"Saddest thing I ever witnessed....an airplane being scrapped"

Bartonsayswhat
Posts: 357
Joined: Sun Oct 28, 2007 8:42 am

### RE: Landing Gear Extension / Retraction Videos.

how many wheels do the 124/225 have out of curiosity?

jetmech
Topic Author
Posts: 2322
Joined: Wed Mar 29, 2006 2:14 am

### RE: Landing Gear Extension / Retraction Videos.

IIRC, the 124 has 4 nose wheels arranged on two posts, and 5 rows of double wheels down each side of the fuselage, which gives 20 wheels. The total is thus 24 wheels.

The 225 again, has 4 nose wheels arranged on two posts, but 7 rows of double wheels down each side of the fuselage, which gives 28 wheels. The total is thus 32 wheels.

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

Bartonsayswhat
Posts: 357
Joined: Sun Oct 28, 2007 8:42 am

### RE: Landing Gear Extension / Retraction Videos.

good to know. by the way, has anyone ever asked you a question that you didn't know? you seem to always have a very good answer for all query's and i am grateful to have knowledgeable people such as you kicking around here for all our questions

HAWK21M
Posts: 30007
Joined: Fri Jan 05, 2001 10:05 pm

### RE: Landing Gear Extension / Retraction Videos.

 Quoting Bartonsayswhat (Reply 23):good to know. by the way, has anyone ever asked you a question that you didn't know? you seem to always have a very good answer for all query's and i am grateful to have knowledgeable people such as you kicking around here for all our questions

Whats good is the effort Jetmech [steve] puts in explanation of each detail accompanied with sketches & pics if available.Truely a good contributer to the site.Its a pleasure to read your posts.

Talking about retraction videos.Has there ever been an incident of a "MLG" retraction on ground erronously on a B737 ever.

regds
MEL
I may not win often, but I damn well never lose!!!

jetmech
Topic Author
Posts: 2322
Joined: Wed Mar 29, 2006 2:14 am

### RE: Landing Gear Extension / Retraction Videos.

Ah hell, thanks gents    . All I can say is that aircraft, engineering and machines in general are a strong interest and hobby of mine, so it is much easier to get enthusiastic about the subject than a lot of other things in life.

I couldn't find and AN225 videos as such, just photos off the database. Anyway, here is a good one of the Lockheed C-5 Galaxy.

Apparently, this is one of taken at some aviation technology institute (India?). I wish we had something like this to play with when I was a technical training school!

This is somewhat off the theme, but there are big, heavy structural parts being moved around by powerful hydraulics, so I think it has a place here!

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

Klaus
Posts: 20707
Joined: Wed Jul 11, 2001 7:41 am

### RE: Landing Gear Extension / Retraction Videos.

Very cool stuff indeed, especially that C-5 video.

In the same vein, here's one of the XB-70 Valkyrie with a comparably weird retraction sequence (starts at about 1:00):

Unfortunate that this complicated maneuver also caused some difficulties, but at least not the ultimate accident.

2H4
Posts: 7960
Joined: Tue Oct 19, 2004 11:11 pm

### RE: Landing Gear Extension / Retraction Videos.

 Quoting Klaus (Reply 26):here's one of the XB-70 Valkyrie with a comparably weird retraction sequence

Nothing like generic '80s power rock to dampen the awe of watching that thing fly.

Thanks for posting the video, though. What a beautiful machine.

2H4
Intentionally Left Blank

Klaus
Posts: 20707
Joined: Wed Jul 11, 2001 7:41 am

### RE: Landing Gear Extension / Retraction Videos.

 Quoting 2H4 (Reply 27):Nothing like generic '80s power rock to dampen the awe of watching that thing fly.

Indeed... I've immediately muted it.

There's a longer one with the Apollo 13 soundtrack... quite a better fit.

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