does a MD-11 need its central main landing gear?

Question

a Md-11's ripped off and it was still standing? any ideas?

Answer 1

As a former DC-10 Flight Engineer (Second Officer) I can assure you the center gear of an MD-11 has nothing to do with Center of Gravity problems. Ray was on the right track with his ACN answer. The more landing gear an airplane has, the better it can spread its weight. This should result in a lower Airplane Classification Number. This is compared with a Pavement Classification Number(PCN) and the ACN should be less than the PCN for continued aircraft operations on that paticular Runway/Taxiway/Ramp. The DC-10 series, -30's and beyond have this extra gear to deal with their increased gross weights. The MD-11 is in fact an upgraded DC-10, but very few were actually retrofitted. It is my understanding that FedEx retrofitted around 10 of their DC-10's, calling them MD-10, but stopped becuase the cost wasn't worth it. Essentially, the modification removed the Flight Engineer Position, saving the cost of paying a 3rd flight deck person. Many MD-11's came straight off the assembly line. MD-11's are used for cargo, but many still fly as passenger aircraft. Yes, the center gear can be damaged while standing still. I am not sure if it will seperate from the aircraft, but this is how it can happen. First, the center gear is canted forward slightly. During refueling the weight of the aircraft begins to compress the struts. Instead of pressing straight down, like the main and nose gear, the center will walk forward slightly. If the parking brake is accidently left on, or the center wheel is chalked, the motion is blocked and the pressure on the center strut is downward and aft, causing damage.
Here is a link showing the canted angle of the center gear. It is the lower right picture, click it for closer view
http://gallery.beezer.com/thumbnails.php?album=15

Answer 2

1

Answer 3

Yes it does, well, sort of, actually the MD 11 is primarily used for freight. It used to be a DC-10, or rather a DC 10 variant. When loading something like the MD 11, especially in a cargo operation, the Centre of gravity moves backwards, well behind that of the main gears so it is possible that the plane can tip backwards, that's where the main gear comes in, as well as loweing the ACN of the plane, I mean it spreads the weight over a larger are so it doesn't do so much damage to the runway when landing.

Answer 4

Md 11 Landing

Answer 5

Previous answers cover it pretty well! Just remember, airplanes generally don't carry anything extra (such as a heavy & superfluous landing gear assembly) for no reason!

I can guarantee that this aircraft will have to undergo an internse inspection looking for structural stress cracks (even after they glue the gear back on.)

Airplanes are pretty tough...there's lots of stories of planes coming back after say, part of the wing was torn off during a mid-air collision...or the such.

But this doesn't mean that the outboard 15 feet of wing isn't "needed."

Sometimes airplanes with a heavy load have to "dump fuel" to lighten the load to return for landing after an emergency. This is done because in some heavy airplanes, the maximum take-off weight is more than the maximum-landing weight...and this is primarily a landing gear stress tolerance consideration.

Answer 6

Nope! they love to waist about $9,000 on something it dont need, also about 600 lbs.