salim
Posts: 301
Joined: Fri Jun 15, 2001 3:27 pm

Wheel Door Open

Mon Apr 29, 2002 8:18 pm


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Photo © Brian Stevenson - Orlando/Tampa Aviation Photography


Why are the wheel doors open on this pic? is it normal?
thanks
salim
 
hkgspotter1
Posts: 5750
Joined: Fri Nov 04, 2005 12:43 pm

RE: Wheel Door Open

Mon Apr 29, 2002 8:24 pm

I guess they are checking something. Its not `normal' for the gear doors to be open.
 
Ndebele
Posts: 2847
Joined: Mon Apr 09, 2001 3:16 am

RE: Wheel Door Open

Mon Apr 29, 2002 9:02 pm

Doesn't that have something to do with the hydraulics? Have a look at that picture:

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Photo © Philipp Wiedenmann


The gear doors are opened, too, and if memory serves right, that LTU 757 pictured above had a loss of hydraulic and thus the gear doors remained open. Probably that TMA A310 pictured above has the hydraulics checked?
But I'm not an expert, maybe you should better ask that question on the tech/ops forum.
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: Wheel Door Open

Mon Apr 29, 2002 10:20 pm

Gear doors are often opened to carry out maintenace in the wheel well. Additionally if for some reason the gear is free-falled the doors will not close again until the system is reset by maintenance
 
BlatantEcho
Posts: 1817
Joined: Wed Sep 27, 2000 10:11 am

RE: Wheel Door Open

Tue Apr 30, 2002 12:22 am

In the LTU 757 picture where the main doors are hanging down, it doesn't look like there is much clearence from the ground.

Does anyone know if a heavier plane, or a hard landing would compress the gear enough that they strick the ground?

I am sure their are procedures for landings as such, but I'm curious to know the particulars.

Regards,
BlatantEcho
They're not handing trophies out today
 
TechRep
Posts: 1877
Joined: Sun Jan 13, 2002 6:53 am

RE: Wheel Door Open

Tue Apr 30, 2002 12:36 am

The gear doors cycle back to close when the gear are extended or retracted, so they will not be a factor on landings. On the ground a bypass handle is pulled allowing the gear doors to be opened. Typically, hydraulics is re-applied and the bypass handle is then closed and the doors will slam back shut. On the larger aircraft B747 and DC-10 if your brave enough, you can ride the gear doors up in lieu of no ladder being present. I never felt comfortable doing it but I have.

TechRep
 
TechRep
Posts: 1877
Joined: Sun Jan 13, 2002 6:53 am

RE: Wheel Door Open

Tue Apr 30, 2002 12:42 am

I forgot to mention in some emergency situations from loss of hydraulic fluid, depending on aircraft, the gear would be allowed to be extended but the main gear doors to conserve fluid resources will not retract back to faired position. So in that case a hard touch down could impact the main gear doors. If an airplane is seen with the gear doors down on approach or while taxiing, then there is some cause for concern.

TechRep
 
BlatantEcho
Posts: 1817
Joined: Wed Sep 27, 2000 10:11 am

TechRep

Tue Apr 30, 2002 1:29 am

Your second reply was what I was getting at, in the event that their is not even pressure to close the doors on landing.....

So they could hit in a situation like that, interesting. Sorry this inerests me so much, do you know if they would chance to break off, just crumple, or what?

I know it would be different for different craft, but have you even seen scrape marks on gear doors when a landing was made with them down?

I'm going to shut up now, but thanks for your replies,
BlatantEcho
They're not handing trophies out today
 
salim
Posts: 301
Joined: Fri Jun 15, 2001 3:27 pm

RE: Wheel Door Open

Tue Apr 30, 2002 2:56 am

Thanks guy for your answers!!!
 
Klaus
Posts: 20594
Joined: Wed Jul 11, 2001 7:41 am

RE: Wheel Door Open

Tue Apr 30, 2002 7:52 am

Wouldn´t it be a serious design error to have the gear doors big enough to impact the runway on a firm touchdown? After all, ripped-off gear doors might cause additional damage to the aircraft in an already difficult situation...
 
TechRep
Posts: 1877
Joined: Sun Jan 13, 2002 6:53 am

RE: Wheel Door Open

Tue Apr 30, 2002 8:02 am

Well bringing the doors back up is not essential and in emergency situations only essential users get power/hydraulics.

Example: When hydraulic reserves are at a critical level, around 1.5 to 2.0 gallons in a 40 ton aircraft, ripping the gear doors off or causing damage to them is of little concern.

TechRep
 
Klaus
Posts: 20594
Joined: Wed Jul 11, 2001 7:41 am

RE: Wheel Door Open

Tue Apr 30, 2002 8:33 am

When hydraulic lines get damaged in the process (when the doors go, so might the actuators), secondary damage could be possible. Possibly affecting the brake lines. Or leaking hyd fluid being spilled on the hot brakes (possible fire hazard).

I just don´t think an airframe designer could afford to take risks like that. My guess is the doors wouldn´t touch the runway as long as the landing gear doesn´t break. (That would have to include surviving complete tyre blowouts without impact.)

Does somebody have any actual evidence one or the other way? I´m just guessing here...
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Wheel Door Open

Tue Apr 30, 2002 9:17 am

The one aircraft family I'm aware that the gear doors contact ground when opened are the DC9/MD80.

On the bottom of the doors are skid bumpers. These are designed to take the brunt of a doors open landing.


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Photo © Jonathan Derden

You're only as good as your last departure.
 
TechRep
Posts: 1877
Joined: Sun Jan 13, 2002 6:53 am

Klaus

Tue Apr 30, 2002 10:02 am

Klaus,

If the doors are impacting the ground that hard hydraulic power is of little concern at that point. The design causes the doors to naturally go to the closed position when they impact the ground, if in fact they even can. They will drag maybe but they will tend to bounce up not shear off. The DC9 family, was what I had in mind, they have a brass/bronze stop to cushion impact when they are opened on the ground.

TechRep

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