Landing Gear

seattle

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Stupid question time for those in the know.

Do modern commercial airliners have some type of load sensing capability in the landing gear to help with weight and balance calculations - not just the squat switch? What about older commercial airliners? Who does the weight and balance calculations at part 121 operators?

Thanks.

Seattle
 

DC9stick

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I understand that some of the state of the art airliners (777) etc. have load sensing computers. For those of us flying antiques we do it with pen and paper on a company/ FAA aproved form in duplicate.
 

TurboS7

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Don't even dare give anyone any idea's, that would bring the whole aviation thing to a grinding halt faster than 911.
 

BigFlyr

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Not even brand new airliners (like the 737-800) have load sensing capability on the landing gear for the purpose of weight and balance, only "ground sensing" capability in the form of squat switches and proximity switches to give information to the air/ground logic computers. You still have to figure the weight and balance the old fashioned way and plot the C.G. on a graph, or use the commercially available software (for some aircraft) to figure the C.G. once the data has been entered into a laptop computer. But that may not be the case for a "state of the art" airplane like the B777 or an A320.
 

TurboS7

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I used to say if the FAA was all that concerned about weight and balance then they need to put a big scale at the end of the runway. When you were at the proper takeoff weight you would get a green light, if you weren't ol' well.....back to the ramp. As a matter of fact they do have one at El Dorado at Bogota, just the keep the frieghters honest.
 

328dude

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I think big flyer was talking about ACARS right? Haven't seen a 737 or A-319 jocky even touch a CG calculator. Atleast not at our airline.

Anywho, getting back to the topic. Didn't the old 727's actually have a hook on the bottom of the plane in which a string with a weight tied to the bottom of it would swing? The ground guys could slide a scale under it and tell the CG of the plane. This was something I heard along time ago and not sure if it was true or not. Hopefully and 727 driver could shed some light on this myth.

Fly safe
 

TurboS7

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No myth fact for the 727 and Learjet and many other models. When doing a "36 month" weight check on the aircraft that is how you determine that it is level. The acutal C.G. is calculated via a simple mathematical equation.
 

TurboS7

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I fly a 737-800 and you will see the first officer frantically punching the numbers in his calculator so we can punch the number into the FMC at the last minute. Since we are a charter operation our procedures have to work at the gate at ATL or literally in Tim Buc Two, Africa.
 

TriStar_drvr

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Nice to know I'm not the only guy "frantically punching the numbers in his calculator" at the last minute before pushback.
 

sydeseet

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The "hook and swing" on the 727 is true, but it isn't for W+B. A metal graph is mounted in the right side wheel well and a pendulem is stored in the Engineers desk. It's used to calibrate the fuel indicators and to level the aircraft.
 

PHX767

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When I was picking up a plane at the McDonnell Douglas factory years ago, we took a tour of a new DC-10 for a foreign carrier. It had some sort of CG indicator that worked by sensing strut loads. you could watch it change as people walked around the plane.

The plumb bob used in most modern transport airplanes is used to dispatch the plane when there is a fuel quantity indicator inop. Integral dipsticks measure the fuel level, then this info along with the plumb bob readings can be used by maintenance to give the fuel quantity in the tank.
 

seattle

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I work at the "Lazy B". One of my co-workers asked me if this was a feature that we (Boeing) offered. I didn't know so I thought I would ask you guys.

Would such a system be marketable to the airlines? Specifically, load cells in each gear assembly that would feed logic inputs to one of the computers - VIA, MCDU, Smart Panel, Other. Or, are weight and balance calculations such a small part of the overall picture that such efforts would be fruitless - either as an STC or offered on new aircraft?

Thanks again.

Seattle
 

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Shem Malmquist
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The MD-11 has the option for this sort of system, but to my knowledge, only Saudi opted for it.
 
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