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Forward and Aft CG Check in W&B Record

avrojockey

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I have a forward and aft CG check in my W&B spreadsheet to give a basic limit check. The values are dependent on a standard passenger weight of 170. FAA raised the summer standard to 190# for 121 last year and wondering if it make sense to do the same. Is it typical to follow the same standard in the 91 world?
 

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I think what’s standard in the part 91 world is to just ask your passengers for their weight. With only 1 (or three for a -10) passenger there’s too much variation to use an average.
 
I have a forward and aft CG check in my W&B spreadsheet to give a basic limit check. The values are dependent on a standard passenger weight of 170. FAA raised the summer standard to 190# for 121 last year and wondering if it make sense to do the same.

Good idea, but... Average weights only make sense when you have a large number of passengers, lots more than an RV-9A carries.

What I did was similar to what you propose... I calculated in advance a number of W&B cases, always including me as the pilot -- my weight is not an FAA statistic -- looking at limit cases. On the back of my checklist -- you do have your own checklist for your own plane? -- I have these cases, all of them with both full fuel and 2 gallons left, to show the c.g. extremes:
* Max passenger seat weight with no baggage and full fuel
* Just me, solo, no baggage for forward c.g.
* Max baggage, then max passengers to gross
* Most aft c.g. with max baggage, 15 gallons fuel, and passengers up to max gross. This is the one case where full fuel was not calculated.

For each of those, I calculated c.g. in %MAC at full fuel and empty. What I found was that if the gross weight is in bounds, it's not possible to get my airplane out of the c.g. envelope with me flying it.

I'd love to have the problem of figuring out how to deal with a forward c.g. in an RV-10, but budget and skyrocketing prices make that a moot point. I'm just glad I got the RV-9A when I did!
 
I think what’s standard in the part 91 world is to just ask your passengers for their weight. With only 1 (or three for a -10) passenger there’s too much variation to use an average.

Operationally thats what's done using my EFB...this is simple check in the W&B record that lets one know if what was removed/installed as a part of the permanent aircraft equipment doesn't wildly throw the CG out in certain loading/fuel scenarios.

The spreadsheet isn't a pilot weight and balance form...it's the maintenance weighing record that stays with the aircraft
 
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I’ll bet with a little practice you can guess anyone’s weight within a few pounds. Many people don’t give accurate weight for a variety of reasons.
 
In the UK, we do a worst forward and worst aft c of g as part of the initial paperwork submission.

189lb heavy pilot

121lb light pilot

One thing to watch is where is the fuel tank moment compared to the zero fuel mass c of g.

On 6,7,8,9,10 it should be forward, therefore your worst forward has you gas it up to gross.

The 12 it is way back, so the opposite occurs.
 
In the UK, we do a worst forward and worst aft c of g as part of the initial paperwork submission.

189lb heavy pilot

121lb light pilot


One thing to watch is where is the fuel tank moment compared to the zero fuel mass c of g.

On 6,7,8,9,10 it should be forward, therefore your worst forward has you gas it up to gross.

The 12 it is way back, so the opposite occurs.

I may need to double those numbers for the US:D
 
In the UK, we do a worst forward and worst aft c of g as part of the initial paperwork submission.

One thing to watch is where is the fuel tank moment compared to the zero fuel mass c of g.

On 6,7,8,9,10 it should be forward, therefore your worst forward has you gas it up to gross.
.

This isn't true for my -10, maybe because I have short legs and hence sit almost full forward. My worst case CG, both solo (forward cg) and loaded (aft cg) occurs when the fuel tank is empty.
 
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