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Useful Load


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So while making lesson plans I'm coming across a lot of confusion on what "Useful Load" is. In our Schweizer book published by Jeppesen, Useful Load is described as "the difference between max takeoff weight and basic empty weight." Then in the old FAA Rotorcraft Flying Handbook the definition is "the difference between the gross weight and the basic empty weight." I couldn't find a definition of useful load in the new rotorcraft flying handbook. So what's the deal? The useful load should include the payload right? And does the pilot fall into payload because he has to be there to produce revenue. And if so, he would also fall into the useful load as well.

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Actually the new rotorcraft flying handbook does have a definition for useful load and it is the same as the old one: "Useful load. The difference between the gross weight and

the basic empty weight. It includes the flight crew, usable

fuel, drainable oil, if applicable, and payload."

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Useful Load is the difference between basic empty weight and the max you can put in it up to gross weight. Yes, the pilot is part of the useful load because all pilots arent the same weight. Payload isnt a W&B term really. Payload would be after the aircraft is fueled, ready to go to include the pilot, how much more weight do you have? It would be different for every configuration. FLying the same helicopter topped off with fuel, but you have a 125lb pilot vs a 300lb pilot, one helicopter will be able to carry payload 175lbs more.

 

Useful load can change based on pilot weight and how much fuel you put in. So will the payload.

Edited by Flying Pig
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Useful Load is the difference between basic empty weight and the max you can put in it up to gross weight. Yes, the pilot is part of the useful load because all pilots arent the same weight. Payload isnt a W&B term really. Payload would be after the aircraft is fueled, ready to go to include the pilot, how much more weight do you have? It would be different for every configuration. FLying the same helicopter topped off with fuel, but you have a 125lb pilot vs a 300lb pilot, one helicopter will be able to carry payload 175lbs more.

 

Useful load can change based on pilot weight and how much fuel you put in. So will the payload.

 

Payload can change based on pilot weight and fuel. Useful load will not. This is a pretty simple thing and you already said the definition. Max gross - empty weight = useful load. As soon as a helicopter comes out of the factory its useful load will not change unless their are changes to helicopter equipment.

 

And yes it is a little bit of a misnomer. Two helicopters can have the same useful load but one can be more useful. If they both have a useful load of 1000 lbs but one burns half as much fuel then one helicopter will have a higher payload for a given amount of endurance.

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Useful load is variable, depending on performance limits at the given time. For example say that the Useful load its 1000 lbs, the difference between Gross Weight and Empty Weight. As long as you have cooler that standard temps you are going to get the predicted performance out of your machine at Gross Weights and at SL, Start going up to higher elevations, Say 5000 ft and a 65 or 75 deg day, now that 1000 lbs maybe only 650 give or take. The books are right they just word it differently. I use to fly a PA-32-300, yea an airplane the principle is the same, where I was flying we never left with out full tanks so that became part of the aircrafts weight, along with me and the junk I would carry, not much just a wiz wheel and some charts. The difference was the useful load or a better term is the paying load. On that particular job, I could carry 680 lbs of either people or freight or a combination of the two. Now on another job, the flights was short, and we didn't need to tanker fuel, because it was not remote, under those conditions, 40 gallons in the tanks was plenty. That gave an extra 360 lbs of paying pax or freight you could carry with the same type of aircraft. give or take how equipped. Its more critical with helicopters, because the nature of flight on the vertical.

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Sorry but that is wrong. Useful load has nothing to do with performance. It is clear cut and simple. MGW-EW= useful load.

Max gross weight may most certainly be reduced by atmospheric conditions, for performance considerations.

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To All,

 

A lot of surprising discussion about some standard definitions.

 

Maximum gross weight - basic empty weight = useful load.

 

Maximum gross weight is established during the certification process and listed in flight manual in the limitations section.

 

Pilots that mentioned varying the maximum gross weight for performance considerations were being prudent but should have stated gross weight, all up weight or take off weight and not "Maximum" gross weight.

 

About changing the Maximum gross weight, this is actually possible via STCs or flight manual supplements. The Bell 407 is a helicopter where this happens. MGW is 5,000# but using FMS-28 it is increased to 5,250# and performance operations are both considered and changed.

 

I suggest that pilots know definitions and then accept that other conditions for specific aircraft can exist.

 

Had to edit to add that MGW can also be decreased by STCs, etc.

 

Be Safe,

 

Mike

Edited by Mikemv
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I have yet to see a helicopter that has different max gross weights. If you know of one please teach me.

 

The A119 Koala (not the MKII) could be considered one when operating at the increased gross weight supplement. I'll try and get the actual RFM excerpt. But you're limited by performance charts as to your gross weight. Maybe JdHelicopterpilot or Clay has a copy. Or maybe someone else that flies the orig Koala.

 

Additionally any part 29 heli that is operating Cat A has a variable gross weight as a limit. It's been a while but I think one over 25k gross weight.

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So while making lesson plans I'm coming across a lot of confusion on what "Useful Load" is. In our Schweizer book published by Jeppesen, Useful Load is described as "the difference between max takeoff weight and basic empty weight." Then in the old FAA Rotorcraft Flying Handbook the definition is "the difference between the gross weight and the basic empty weight."

 

So what's the deal?

 

I suggest that pilots know definitions and then accept that other conditions for specific aircraft can exist.

 

Mike

 

The deal is exactly as stated in Mikemv’ post above:

 

“I suggest that pilots know definitions and then accept that other conditions for specific aircraft can exist.

 

There’s information and limitations that were established during the initial certification and STC process, listed in your flight manual, that aren’t always apparent. One problem is, many new instructors were never taught the real specifics of the certification/STC process, so the not so apparent, sometimes hidden information, never got past on.

 

To determine the useful load of an aircraft, subtract the empty weight from the maximum allowable gross weight. Some helicopters are certificated and supplemented by STC with different maximum gross weights for specific operations. Therefore, they may have more than one useful loads listed.

 

Taking the Schweizer 300C as an example. With the Cargo Hook STC installed your maximum operating gross weight is 2150 lbs. However, the maximum takeoff and landing gross weight (allowable on the landing gear) is 2050 lbs. The result is your external useful load is 100 lbs. higher than your internal useful load.

 

If we look at the MD500, it throws a new term at us, “maximum rotorcraft load combination operating gross weight.” With its Cargo Hook STC installed your maximum rotorcraft load combination operating gross weight is 3550 lbs. However, the maximum takeoff and landing gross weight (allowable on the landing gear) is 3000 lbs. The result is your external useful load is 550 lbs. higher than your internal useful load.

 

These two different useful loads are true for other helicopters too, Bell 214B, Bell 407, and AS350 to name a few.

 

Some others have the same useful load regardless of the type operation.

 

Scan-11-1.jpg

 

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Edited by iChris
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Here is the Limitations section from the increased gross weight Appendix showing a variable gross weight. Unusual, but it's here in the A119. Oddly enough, it was developed by an inspector that did not like the way the aircraft autorotated at altitude. You can see a great difference in performance charts when going from an operational weight of 5621 to 5622.

 

 

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Edited by C of G
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I understand all of this however I think the terminology is what confuses me and other prospective CFI's. Useful load should be used in a number of different ways. In a 300C the useful load of the cabin is 600 lbs. Yes, if you put a hook on it, you can a greater Max Gross because that weight is not being supported by the skids. But if you have a helicopter with a BEW of 2000 lbs and a Max Gross of 3000 lbs, then the total "potential" Useful Load is 1000 lbs. However, people rarely ever fly a helicopter at Max Gross (probably, I'm sure some do) so if we only loaded that helicopter with 500 lbs of cargo (payload) then the useful load would be 500 lbs. It seems like there are two completely separate ideas tied to useful load. Potential, and Actual. Does this make sense to anyone, please correct me if I am wrong. Just trying to figure this out. Thanks.

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Depends on what job is being done. We have to calculate usefull load every day and every time we switch helicopters because every one is different and we go max gross several times a day.

 

Calculate useful load, subtract for the pax, and see what's left for fuel :-). Hopefully there is enough, if not, drop a passenger and make two trips.

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I understand all of this however I think the terminology is what confuses me and other prospective CFI's. Useful load should be used in a number of different ways. In a 300C the useful load of the cabin is 600 lbs. Yes, if you put a hook on it, you can a greater Max Gross because that weight is not being supported by the skids. But if you have a helicopter with a BEW of 2000 lbs and a Max Gross of 3000 lbs, then the total "potential" Useful Load is 1000 lbs. However, people rarely ever fly a helicopter at Max Gross (probably, I'm sure some do) so if we only loaded that helicopter with 500 lbs of cargo (payload) then the useful load would be 500 lbs. It seems like there are two completely separate ideas tied to useful load. Potential, and Actual. Does this make sense to anyone, please correct me if I am wrong. Just trying to figure this out. Thanks.

 

 

Not withstanding the rare exceptions, and understanding the difference between internal and external limits, your useful load doesn't change. It's a fixed number based on an aircrafts configuration in relation to its limit.

 

Consider it as a fixed number. How much you actually use doesn't change it's value. Take for example my bathroom scale. It goes up to 310lbs. Just because I'm not using that much when I step on it doesn't change it's fixed value. Not a perfect example but it's all I got on short notice.

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From the new rotorcraft handbook:

 

Useful load. The difference between the gross weight and the basic empty weight. It includes the flight crew, usable fuel, drainable oil, if applicable, and payload.

 

From the weight and balance handbook:

 

 

Useful Load. (GAMA) Difference between takeoff weight, or ramp weight if applicable, and basic empty weight.

 

Takeoff Weight. The weight of an aircraft just before beginning the takeoff roll. It is the ramp weight less the weight of the fuel burned during start and taxi.

 

Ramp Weight. The zero fuel weight plus all of the usable fuel on board.

 

Just to make it muddy.

 

 

http://www.faa.gov/library/manuals/aircraft/media/FAA-H-8083-1A.pdf

 

 

 

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Well after talking with my Chief Pilot the other day, he told me if you use an FAA definition during an FAA check ride, there is absolutely no way they can say you're wrong. Even though my Jeppesen Schweizer Helicopter Pilot Textbook states that Useful Load is the difference between the Max Takeoff Weight and the Basic Empty Weight. I'm gonna go with the FAA's definition. Can't go wrong there.

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