a380900
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Can One Land With Extended Gear Doors?

Mon Feb 16, 2009 11:51 am

Is it a design requirement that you could land a plane with the gear doors extended without damage to them? Or do engineers disregard this? Does it depend on the plane?
 
EMBQA
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RE: Can One Land With Extended Gear Doors?

Mon Feb 16, 2009 12:37 pm

Yes... you can. Aircraft that have body doors are designed to clear the ground. If you look in the data base there are several pictures of just that case. 757 is a biggie.....
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
Tristarsteve
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RE: Can One Land With Extended Gear Doors?

Mon Feb 16, 2009 1:17 pm

When the undercarriage is extended in emergency by using the freefall handles/switches, the gear doors will open and not close again.
In many cases the main gear doors will touch the runway when the aircraft lands, but there are rub strips built into the doors for this.
On the B747, if you open the body gear doors on the ground, it is very possible that they will hit the wheels if the aircraft is heavy. Good catch this. You open them on arrival, refuel the aircraft, then can't close them again!
 
broke
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RE: Can One Land With Extended Gear Doors?

Mon Feb 16, 2009 1:50 pm

The main gear doors on the DC-9's will drag if the airplane lands with them open. The reason for landing with the doors open would be a manual gear extention with no hydraulics. Douglas designed a system of cranks, cables, and pulleys to manually closed the doors; the system was unwieldy and unreliable.
The final fix was to install a skid on each main landing gear door. If you landed with the doors open, just change the skids.
 
DH106
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RE: Can One Land With Extended Gear Doors?

Mon Feb 16, 2009 3:12 pm

The new A380 has all sorts of little fillets on it's gears doors designed to allow them to be opened in various scenarios. General retraction/extention with oleos extended & bogies tilted requires a little fillet on the inner body gear doors to fold to clear the rear wheels of the tilted 6 wheel bogie. There's a similar fillet further forward on the same door that I speculate is for when the doors need to be opened on the ground with bogie flat & oleos compressed - to clear the center axle wheels of the body gear bogie. Also, the inner wing gear doors have a fillet at their rear edge that doesn't open with the rest of the door but folds up into the fuselage. This is so the door edge clears the body gear front wheels which protrude slightly into the wing gear well area.
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PGNCS
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RE: Can One Land With Extended Gear Doors?

Mon Feb 16, 2009 5:45 pm



Quoting A380900 (Thread starter):
Is it a design requirement that you could land a plane with the gear doors extended without damage to them?

It's not a requirement, though in most cases the doors won't contact the ground.

Quoting EMBQA (Reply 1):
Yes... you can. Aircraft that have body doors are designed to clear the ground.

Not all do. DC-9/MD-80/MD-90 gear doors sit on the ground after manual extension (loss of right hydraulic system being the common scenario). They are designed to be aerodynamic to an extent and as the aircraft slows they gradually lower to the ground onto big blocks of metal which are all that gets scraped (if it all works correctly, and it usually does). Of course maintenance will come and pin the gear and stow the doors before the aircraft moves off the runway.

Of course the 737 gets around the issue altogether by not having main gear doors.

Quoting Broke (Reply 3):
The main gear doors on the DC-9's will drag if the airplane lands with them open. The reason for landing with the doors open would be a manual gear extention with no hydraulics.

 checkmark  Or without the right system, anyway.
 
boeing767mech
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RE: Can One Land With Extended Gear Doors?

Mon Feb 16, 2009 10:19 pm



Quoting A380900 (Thread starter):
Is it a design requirement that you could land a plane with the gear doors extended without damage to them?

The flight test airplanes of the Convair 880's had the MLG gear doors openned until the gear was retracted, during flight test the sequence valve for the doors was changed.

http://www.youtube.com/watch?v=BsRcRxXv1V8

you can see it in this video.

David
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avt007
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RE: Can One Land With Extended Gear Doors?

Tue Feb 17, 2009 3:13 am

The F28 doors hit the ground, so there was a crank and pulley system for the crew to use to raise them enough not to drag. Some had the pulley in the galley floor, but that might upset the pax. Others had the pulley in the flight deck.
 
DeltaGuy
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RE: Can One Land With Extended Gear Doors?

Tue Feb 17, 2009 3:38 am

You can land a Gulfstream doors-down as well.

Now how about a 737? Wait...not a problem.

DeltaGuy
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DH106
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RE: Can One Land With Extended Gear Doors?

Tue Feb 17, 2009 6:56 am

The British 1-11 had the same problem as the DC-9/MD-80/90 - open doors will drag as the aircraft sits low on the ground.
...I watched c-beams glitter in the dark near the Tanhauser Gate....
 
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HAWK21M
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RE: Can One Land With Extended Gear Doors?

Tue Feb 17, 2009 8:07 am

Sure can on a B757.If the Alt gear extension is utilised,there is no means of retracting the doors.
regds
MEL
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avt007
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RE: Can One Land With Extended Gear Doors?

Tue Feb 17, 2009 11:34 pm

For that matter, an F28 can land with the cabin door open with only minor scrapes.
 
KELPkid
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RE: Can One Land With Extended Gear Doors?

Wed Feb 18, 2009 6:16 am



Quoting A380900 (Thread starter):
Is it a design requirement that you could land a plane with the gear doors extended without damage to them?

Certainly not the case with the Cessna 210...I was on board one once when a hydraulic gear sequencer acted up, and the doors remained open. Shower O' Sparks time  Wow! The aircraft had to have the gear doors to be replaced after that incident.
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DH106
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RE: Can One Land With Extended Gear Doors?

Wed Feb 18, 2009 6:49 am

Quoting KELPkid (Reply 12):
Certainly not the case with the Cessna 210...I was on board one once when a hydraulic gear sequencer acted up, and the doors remained open. Shower O' Sparks time The aircraft had to have the gear doors to be replaced after that incident.

Really? Didn't think the 210 had doors on the mains - don't they just pivot back into holes in the rear fuz?



No, you're right on checking photos - some do have doors.  Smile

[Edited 2009-02-17 22:52:44]
...I watched c-beams glitter in the dark near the Tanhauser Gate....
 
KELPkid
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RE: Can One Land With Extended Gear Doors?

Wed Feb 18, 2009 7:00 am



Quoting DH106 (Reply 13):
Really? Didn't think the 210 had doors on the mains - don't they just pivot back into holes in the rear fuz?

Depends on the model. The last 210's built didn't have gear doors (on the mains), and a popular STC mod is to remove the gear doors and replace them with the flush fitting skin from later 210's. The 1962 210B definitely has gear doors on the mains, and another door for the gear legs. It is very similar to an airliner, in that the main gear doors are only supposed to be open during the extension and retraction sequences. If you know what you are doing, you can even open them on the ground for a pre-flight inspection (I don't remember how to do this without making her end up on the belly).
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HAWK21M
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RE: Can One Land With Extended Gear Doors?

Wed Feb 18, 2009 7:00 am



Quoting DH106 (Reply 13):
some do have doors.

Why the option?
regds
MEL...
I may not win often, but I damn well never lose!!! ;)
 
KELPkid
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RE: Can One Land With Extended Gear Doors?

Wed Feb 18, 2009 6:32 pm



Quoting HAWK21M (Reply 15):
Why the option?
regds
MEL...

Hi MEL, it wasn't really an option, Cesnna deleted main gear doors (and the gear leg doors, too) on most late-production (1979-1986) single retracts. The door mechanism system is inordinately complex (a hydraulic plumbing and micro-switch nightmare), and prone to failure. Mechanics who know the Cessna retract system well are sought after by the owners of such birds for this reason...  Wink

However, a few people have STC'ed refitting earlier Cessna retract single gear doors with the "wheel slots" from later models, which significantly improves the system from a maintenance point of view.
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PC12Fan
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RE: Can One Land With Extended Gear Doors?

Wed Mar 11, 2009 12:17 am

I've actually seen a couple emergency landing on the DC-9/MD-80 series when the main doors are down. Makes a neat show but they are designed to handle those scenarios.
Just when I think you've said the stupidest thing ever, you keep talkin'!
 
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HAWK21M
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RE: Can One Land With Extended Gear Doors?

Thu Mar 12, 2009 9:15 am



Quoting KELPkid (Reply 16):
However, a few people have STC'ed refitting earlier Cessna retract single gear doors with the "wheel slots" from later models, which significantly improves the system from a maintenance point of view.

Interesting.
Also a def weight saving here too.How much approx?
regds
MEL.
I may not win often, but I damn well never lose!!! ;)

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