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What If? An Airliners Wheels Didn't Come Down?  
User currently offlinePawsleykat From United States of America, joined Jul 2005, 1978 posts, RR: 11
Posted (9 years 4 months 1 week 3 days 8 hours ago) and read 4585 times:

Hiya.
Yes, I do know this photo is a fake (click on the link), but what if an A340 or a 747's main wheels, the ones under the wings, refused to fold down. Could they land like this?

www.cardatabase.net/modifiedairliner...earch/photo_search.php?id=00005394

Just a question.
I am prepared for lashings and laughs.

JG


First Class passengers are my favourites. They can't get any further forward without an ATPL.
31 replies: All unread, showing first 25:
 
User currently offlineFrancoflier From France, joined Oct 2001, 3845 posts, RR: 11
Reply 1, posted (9 years 4 months 1 week 3 days 8 hours ago) and read 4577 times:

Belly landing. It's happened a few times already, but most of those times the gear was partially extended.

A short slide, a few sparks, not that big of a deal, really, except the media would be all over it like it was the end of the world, as usual...



Looks like I picked the wrong week to quit posting...
User currently offlineAir2gxs From , joined Dec 1969, posts, RR:
Reply 2, posted (9 years 4 months 1 week 3 days 6 hours ago) and read 4519 times:

An aircraft in the condotion of the photo would simply retract the gear and belly in. Aircraft have done it rather successfully in the past.

A B747 can land with the wing and nose gear extended, it may be able to do it with the body and nose, but I suspect balance is an issue. With the wing gear cg is the issue.


User currently offline320tech From Turks and Caicos Islands, joined May 2004, 491 posts, RR: 5
Reply 3, posted (9 years 4 months 1 week 3 days 6 hours ago) and read 4518 times:

Remember too, that an airliner has more than one way to get the gear down. If the regular way doesn't work, the pilots can use the alternate extension. Typically, it's a cable operated system that first opens the gear doors, then drops the gear. There may be a separate hydraulics system to lock down the gear.


The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 4, posted (9 years 4 months 1 week 2 days 14 hours ago) and read 4370 times:

The last time I remember an airliner having a gear not extend it was because a large, hard rubber chock was left in the wheel well and the gear jammed against it on retraction. They knocked the gear down by bouncing the plane on the other main and the nosewheel a couple of times. Boeing then advised them that, even though the outcome was successful, the nosegear was probably not strong enough for such use and that they might have been safer landing will all retracted.

That is one prevalent school of thought; that all UP is better than any combination of UP and DOWN. Most landing gear problems are just indication failures. The gear is DOWN but the bulb is burned out or something like that.

It does take some extraordinary event to cause a gear not to extend on a modern airliner.

In my career I've had to go back and peek through the periscope at the maingear twice, and send a jumpseater back once. In all three cases we were fine and landed without incident.

Slam
- now where is that periscope
Click

[Edited 2005-08-14 17:30:54]


Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 5, posted (9 years 4 months 1 week 2 days 12 hours ago) and read 4317 times:

All Airliners have a secondary means to extend the Gear either Manually or Hydraulically.
In case that does not function then jerking the Aircraft is an option & flying over tower to confirm Gear down is an option.
Finally its a belly landing.

Quoting SlamClick (Reply 4):
The last time I remember an airliner having a gear not extend it was because a large, hard rubber chock was left in the wheel well and the gear jammed against it on retraction. They knocked the gear down by bouncing the plane on the other main and the nosewheel a couple of times.

Remember that Incident too.

Quoting SlamClick (Reply 4):
The gear is DOWN but the bulb is burned out or something like that.

Red light out,No green = doubt.

Quoting SlamClick (Reply 4):
In my career I've had to go back and peek through the periscope at the maingear twice, and send a jumpseater back once. In all three cases we were fine and landed without incident.

In Cargo since its not possible to access the Main deck in flt,a secondary L/G Indication is installed.

regds
MEL



Think of the brighter side!
User currently onlineKlaus From Germany, joined Jul 2001, 21521 posts, RR: 53
Reply 6, posted (9 years 4 months 1 week 2 days 9 hours ago) and read 4283 times:

Aren´t the indicators nowadays equipped with muiltiple LEDs per position to reduce the probability of an indicator failure?

User currently offlineMD11Engineer From Germany, joined Oct 2003, 14139 posts, RR: 63
Reply 7, posted (9 years 4 months 1 week 2 days 6 hours ago) and read 4244 times:

Unfortunately all aircraft i have worked on, including very modern ones, still use little peanut lightbulbs in the indicator assemblies (e.g. P/N 387).

I don't know why they didn't move to LED technology long ago. The little lightbulbs keep on burning through.

Jan


User currently offline320tech From Turks and Caicos Islands, joined May 2004, 491 posts, RR: 5
Reply 8, posted (9 years 4 months 1 week 2 days 5 hours ago) and read 4226 times:

I don't know why they didn't move to LED technology long ago.

Because our modern, high tech aviation business is stuck firmly in 1957.  Wink



The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 9, posted (9 years 4 months 1 week 2 days 4 hours ago) and read 4207 times:

The last time I remember an airliner having a gear not extend it was because a large, hard rubber chock was left in the wheel well and the gear jammed against it on retraction

Slam..?

Wasn't that the famous USAir 737-300 in CLT in the late '80's..? They never did get the right leg down and ended up dragging the wing in.



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently onlineKlaus From Germany, joined Jul 2001, 21521 posts, RR: 53
Reply 10, posted (9 years 4 months 1 week 1 day 20 hours ago) and read 4142 times:

Quoting MD11Engineer (Reply 7):
I don't know why they didn't move to LED technology long ago. The little lightbulbs keep on burning through.

Weird indeed. By now LEDs should be bright enough to replace any light bulb even under full daylight. That would have been the only possible reason against the change I could think of...


User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 11, posted (9 years 4 months 1 week 1 day 19 hours ago) and read 4140 times:

Quoting MD11Engineer (Reply 7):
I don't know why they didn't move to LED technology long ago. The little lightbulbs keep on burning through.

One of the few remaining mysteries of Aviation  Smile
regds
MEL



Think of the brighter side!
User currently offlineFergulmcc From Ireland, joined Oct 2004, 1916 posts, RR: 52
Reply 12, posted (9 years 4 months 1 week 1 day 19 hours ago) and read 4137 times:

Quoting Air2gxs (Reply 2):
A B747 can land with the wing and nose gear extended, it may be able to do it with the body and nose, but I suspect balance is an issue. With the wing gear cg is the issue.

True, Take the body gear out on a 747 and it will fall back. I even remember having to put a good bit of weight in the front cargo hold after a maintenance check as the fuel tanks would be empty, so that it can be pushed out of the hanger to be fueled up outside.

Fergul Big grin  sun 



Zambian Airways, Where the Eagles fly free!!
User currently offlineMrocktor From United States of America, joined Jan 2005, 1672 posts, RR: 49
Reply 13, posted (9 years 4 months 1 week 13 hours ago) and read 3975 times:

Gear up landing is really no big deal. The aircraft is designed for this condition from a structural and systems standpoint. The main concerns are structural integrity and fire protection.

An excerpt from AC 25.994-1:

5 ACCEPTABLE MEANS OF COMPLIANCE.
a. The airplane fuel system should be designed to minimize the spilling or
leaking of fuel from damaged components during and following a wheels-up landing.
The unpreventable release of fuel, such as from severed or punctured fuel lines
downstream from shutoff valves, should be diverted or excluded to the maximum
extent practicable from spreading to likely ignition sources.

b. Fuel lines and fuel system components should be located and routed as
far as practicable from likely impact areas and from areas where structural
deformation may cause crushing, severing, punctures or high tensile loads in the
lines.

C. Fuel lines should be constructed to protect their integrity during and
after a wheels-up landing. Flexible and stretchable hoses should be used or the
fuel line should be designed to allow stretching or movement with the deformed
structure up to an amount likely to be required to prevent failure under high
tensile or shear loading. Flexible hoses should also be designed and qualified
to absorb the energy that would likely be imparted to the component or fuel line
from direct impact resulting from structural failure.

d. Fuel lines and fuel system components within the engine nacelle should
be arranged and protected to the maximum extent possible so that spilled fuel
caused by damage to lines or components from a wheels-up landing is not likely
to contact hot engine surfaces (over 400° F.). Fuel lines and components should
be shrouded and drained to accomplish this protection.

e. In areas of the engine nacelles, pylons, and airplane fuselage that are
susceptible to being damaged by a wheels-up landing, fuel lines and electrical
wiring should be isolated, separated and routed to the maximum extent
practicable, to minimize the hazards of spilled fuel flowing into an area
containing a potential ignition source. In addition, electrical components
should be acceptable for operation in flammable leakage zones identified in
accordance with 9 25.863.

f. Shielding and drainage may be used wherever it is considered appropriate
to prevent spilled fuel from spreading to potential ignition sources or
occupied areas. Drip fences and drainage troughs can be used to divert flow of
spilled fuel from potential ignition sources such as hot engine cases,
electrical accessories, and component compartments. Nonconductive material
should be used to shroud electrical wiring that might be damaged by deforming
structure.

g. Fuel shutoff valves should not be located within the engine nacelles,
pylon areas or adjacent to engine air intakes and exhausts where they may be
subjected to damage from impact and scraping action during a wheels-up landing.
Fuel shutoff valve mountings should, as a minimum, be designed for the inertial
loads listed in 8 25.561 unless the location and estimated loads in the area
impose a greater strength requirement to maintain the shutoff valve mounting
integrity.

h. Installation of auxiliary fuel tanks and systems in the fuselage should
be based on the guidance and information in AC 25-8, Auxiliary Fuel System
Installations.


mrocktor

[Edited 2005-08-16 18:44:09]

User currently offlineKhenleyDIA From Sweden, joined Feb 2005, 427 posts, RR: 0
Reply 14, posted (9 years 4 months 1 week 11 hours ago) and read 3932 times:

Quoting Klaus (Reply 10):
Weird indeed. By now LEDs should be bright enough to replace any light bulb even under full daylight. That would have been the only possible reason against the change I could think of...

Here is another option. I know that in an accident investigation, don't they check the bulbs to see if they were on during the crash by looking at the filament?? Can they do the same thing with LEDs? Not sure if that would even be reason enough, but just figured that I would mention that option.

KhenleyDIA



Why sit at home and do nothing when you can travel the world.
User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 25
Reply 15, posted (9 years 4 months 1 week 8 hours ago) and read 3908 times:

Is a landing gear indicator light not included in the lightbulb spares in the flight deck?

I guess that a blown light doesnt apply to those aircraft with EICAS or ECAM systems as it will just appear on the GEAR status page?



Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offlineAirplanePeanut From United States of America, joined Mar 2004, 452 posts, RR: 0
Reply 16, posted (9 years 4 months 1 week 8 hours ago) and read 3903 times:


View Large View Medium
Click here for bigger photo!

Photo © Michael Ciasullo




  Peanut



[Edited 2005-08-17 00:02:15]


..
User currently offlineAir2gxs From , joined Dec 1969, posts, RR:
Reply 17, posted (9 years 4 months 1 week 7 hours ago) and read 3885 times:

Quoting Kaddyuk (Reply 15):
guess that a blown light doesnt apply to those aircraft with EICAS or ECAM systems as it will just appear on the GEAR status page?

All the aircraft I'm aware of with EICAS and ECAM use the lights as primary indication. The computers let you know only if there is a problem via a gear config message or a gear not down message (both of those are EICAS, don't recall the ECAM message).


User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 18, posted (9 years 4 months 1 week 4 hours ago) and read 3858 times:

Quoting EMBQA (Reply 9):
Wasn't that the famous USAir 737-300 in CLT in the late '80's..? They never did get the right leg down and ended up dragging the wing in.

That was the one, and video of the bounce attempt, and second approach to a landing is on the net somewhere.

Southwest landed with the same configuration at ONT in 1996, but the cause was different. No gear bounce on that one... Our QRH specifically prohibits gears bounces and high-G manuevers to get the gear down.

BTW, the 737NG variants don't have the viewer in the cabin floor for the main gear. two seperate sensors now....


User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 19, posted (9 years 4 months 5 days 13 hours ago) and read 3664 times:

Quoting OPNLguy (Reply 18):
BTW, the 737NG variants don't have the viewer in the cabin floor for the main gear. two seperate sensors now....

On the B737 Freighters the Secondary MLG indication is transmitted by Microswitches on the LG unlike the Proximity switches for the Primary LG indication.
regds
MEL



Think of the brighter side!
User currently onlineKlaus From Germany, joined Jul 2001, 21521 posts, RR: 53
Reply 20, posted (9 years 4 months 4 days 17 hours ago) and read 3586 times:

Quoting KhenleyDIA (Reply 14):
Here is another option. I know that in an accident investigation, don't they check the bulbs to see if they were on during the crash by looking at the filament?? Can they do the same thing with LEDs?

You´re right, I forgot about that. No, you would not be able to find such a difference with LEDs.

But as long as there´s "backup information" available through the information screens it´s probably not a serious problem.


User currently offlineAbbs380 From United States of America, joined Mar 2005, 120 posts, RR: 0
Reply 21, posted (9 years 3 months 4 weeks 1 day 21 hours ago) and read 3451 times:

Many years ago, a relatively new TWA B767 was flown from (I think, SFO) where it had just had a brake change, to STL. When the gear was selected down on approach, the rh. mlg would not extend. The crew tried everything to get the gear down but could not get it to go, so they diverted to Scott AFB in Ill. and landed with the right gear up. Long story- short version- When the mechs. replaced the brake, they reinstalled the torque arm bolt and nut, but forgot to put a cotter pin in the nut, so, in flight the nut backed off and the bolt dropped out. At some point the torque arm rotated out of position so that when the gear tried to extend, the torque arm hung up on structure and the gear could not go down. Only the few minor injuries to crew/pax but lots of damage to the a/c.

User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 22, posted (9 years 3 months 4 weeks 1 day 21 hours ago) and read 3444 times:

Quoting Abbs380 (Reply 21):
and landed with the right gear up.

Why did they not opt for a belly landing.What happened to the RH side Wing structure on Impact.Was the Aircraft a write off or did it fly again.
regds
MEL



Think of the brighter side!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17173 posts, RR: 66
Reply 23, posted (9 years 3 months 4 weeks 1 day 15 hours ago) and read 3402 times:

Quoting HAWK21M (Reply 22):
Quoting Abbs380 (Reply 21):
and landed with the right gear up.

Why did they not opt for a belly landing.What happened to the RH side Wing structure on Impact.Was the Aircraft a write off or did it fly again.
regds
MEL

Normally in these cases the gear won't come back up either.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineAbbs380 From United States of America, joined Mar 2005, 120 posts, RR: 0
Reply 24, posted (9 years 3 months 4 weeks 23 hours ago) and read 3313 times:

Mel, I think this happened about 1987 so it was a while ago, here is how I remember it. A mechanic I knew said he watched the landing, he said it was very smothe on the left main then the nose. Because the 767 engines hang down so far there was little damage to the sheet metal, and the wing structure was strong enough to support the load. IIRC they jacked the wing up and got the gear under it then changed the engine, removed the rh mlg door (which obviously was very damaged) and flew it about 300 mi. to TWA/s main mx base in Kansas City where it was repaired. It was not a W/O.

25 HAWK21M : Must have been great for Mx to see it fly again.Any Aircraft ID. regds MEL
26 Post contains links Abbs380 : Mel, cant remember, but did find a link. http://ils.unc.edu/~viles/172i/users/big/docs/AP881103-0166
27 Abbs380 : Holy cow, I was just rereading this thread. The TWA thing happened in AUG.87. Im not superstitious.
28 Ballpeeen : The CRJ series of aircraft have no separate indication lights. Gear indication is solely on EICAS, and consisits of three boxes that are green when d
29 HAWK21M : Nice link.Was a Retraction test carried out.I presume so & did the post retraction test Inspection show any abnormality. regds MEL
30 Post contains links and images YYZYYT : Um, not so farfetched... as is noted, apparently yes, they can land like that: View Large View MediumPhoto © Perry harris View Large View Medium
31 Jetlagged : The bulbs are the same regardless of which annunciator they illuminate. Even the most ham fisted pilot should be able to change the bulb if the light
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