B767 Landing gear

[cowpatz]

Just learn't something very interesting the other day with respect to the landing gear geometery on the 767.
The original gear was built for the 767-100 series (which was never produced). It had a smaller footprint but would have made it ineligable to land at places like LGA and SFO.
A bigger gear was produced which also had an offset. There was a glitch in the design that was picked up during the first retract testing cycle whereby the gear smashed a hole through the top surface of the wing. Rather than go through the costly process of redesigning the gear they made a pop up panel. The top of the gear has a wheel on it that rubs against the panel (which is greased) and pops the panel open during a period of the arc of the retract/extend cycle. A powerful spring holds the panel closed when the gear is either fully up or down.
A bizarre fix (and one more likely the poms would use in their designs) but it works. The 767-400 apparently has different gear being the same as the 777 but with 4 wheels and not 6.

The 767 gear is not the most forgiving (and hangs the wrong way) but it works well anyway as can be seen in this video getting a hammering in a 35 kt crosswind landing at Birmmingham:

[Ian Warren]

QUOTE (cowpatz @ Apr 11 2014,3:22 PM) <{POST_SNAPBACK}>

Just learn't something very interesting the other day with respect to the landing gear geometery on the 767.

Strangely I was studying the wings more the UC, .... but from a distance and the lense of a camera those bogies appeared to be going through hell.

[Charl]

I love hearing titbits like this... amazing, a real Oh Dear moment for the design team.
It's why they spend so much time testing the final product before unleashing it on the unsuspecting customer.
Even then (Culled from pprune):
"Whilst at LHR my company took delivery of 767s. Factory to XXX to LHR. Aforementioned panel, mistaken on gnd for access panel (flush obviously) but not secure, so taped down whilst at XXX, and entered in techlog. Subsequent inspection at LHR would find tape torn and tattered, and requiring replacement!! Bit of 'investigation' revealed that hinged panel there for reason..... gear transition, hence tattered tape!! "

That clip caused me physical pain... great post Steve.

[cowpatz]

Charl that's classic!

You can just see the panel here.
Not sure of the copyright on this so I have just linked it.

[NZ255]

QUOTE (cowpatz @ Apr 11 2014,4:33 PM) <{POST_SNAPBACK}>

Charl that's classic!

You can just see the panel here.
Not sure of the copyright on this so I have just linked it.

Is it on top of the wing? How did the gear make a hole in the wing? doesn't it retract into the belly?

[Ian Warren]

QUOTE (NZ255 @ Apr 11 2014,5:48 PM) <{POST_SNAPBACK}>

Is it on top of the wing? How did the gear make a hole in the wing?

The main gear eloe's 'legs' are built on the and connected to the wing spar structure, this helps absorb heavy landings on the main fuselage frame (there are three points), one of the strongest areas trust to handle the load/engine/fuselage weights and landing stress's , a to heavy landing can and will press through the wing after breaking, not spose to happen but heavy landings or weather affects also design to crimp for the safety of the PAX .. the aircraft of course gets trashed but some do get rebuilt.

[Charl]

QUOTE (NZ255 @ Apr 11 2014,4:48 PM) <{POST_SNAPBACK}>

Is it on top of the wing? How did the gear make a hole in the wing? doesn't it retract into the belly?

There was a new bit of the modified gear that sticks out next to the hinge pin.
As the gear rotates on retraction this sticky out bit finds itself meeting the upper wing surface.
It's a simple enough bit of geometry, and clearly the design team would have been under pressure to miss it.
So all they did was put a wheel on the end of the sticky out bit, and it pushes the panel open momentarily.

[NZ255]

Haha, thanks for the explanation guys. That's quite funny...

I was looking for some videos but it appears the panel is too close to the fuselage to be included in a video of the wing at takeoff.

[SA227]

And if you have a gear problem you could ask the little old lady in 24K if she saw the panel move up and back down.

Sounds like a brilliant little bit of information for an annual refresher course.