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RV-12 Weight & Balance Question — Left/Right Main Difference

VansRV12Driver

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I recently had a new weight and balance performed on my RV-12 and wanted to ask the group whether the results seem reasonable.

The prior weight and balance, performed several years ago, showed the left and right mains within about 1 lb of each other. The new calculation shows a 22 lb difference between the left and right mains:

Left Main: 290 lb
Right Main: 312 lb
Nose: 162 lb
Total Empty Weight: 764 lb

The previous empty weight was 743 lb, so the airplane is now showing approximately 21 lb heavier overall. I am not aware of any equipment additions or configuration changes that would explain that increase. In fact, the prior weighing included the wheel pants installed, while the current weighing was done with the wheel pants removed, so I would have expected the weight to be slightly lower, not higher.

The A&P who performed the new W&B indicated that it was done with empty fuel. Under the original W&B, the builder indicated that zero fuel was calibrated. Assuming both are accurate, that seems to make a fuel quantity issue less likely, but I am still trying to understand the result.

One thing that seems odd to me is that the increase in total empty weight versus the prior W&B is about 21 lb, while the difference between the left and right mains is 22 lb. That may be purely coincidental, but I’m curious whether anyone with RV-12 weighing experience thinks that pattern suggests a possible setup, scale, or measurement issue.

A few questions for those with RV-12 weighing experience:

  • Does a 22 lb difference between the left and right mains seem plausible on an RV-12, or would that make you suspect a weighing/setup issue?
  • If the prior W&B had the mains within 1 lb, would you expect a later weighing to vary this much side-to-side absent a major equipment/configuration change?
  • If the airplane was weighed with empty fuel, and the original W&B also indicated calibrated zero fuel, are there any RV-12-specific issues that could still explain both the total empty weight increase and the side-to-side main difference?
  • Are there common weighing setup issues that could create this kind of discrepancy — scale height mismatch, aircraft not laterally level, scale/tare issue, wheel not centered on the scale, brake drag, etc.?
I understand the prior W&B could have been wrong, and I am not assuming the new one is necessarily incorrect. I am just trying to determine whether this result is within the range of normal experience or whether I should request a reweigh before accepting the new numbers.

Thanks in advance for any guidance.
 
I recently had a new weight and balance performed on my RV-12 and wanted to ask the group whether the results seem reasonable.

The prior weight and balance, performed several years ago, showed the left and right mains within about 1 lb of each other. The new calculation shows a 22 lb difference between the left and right mains:

Left Main: 290 lb
Right Main: 312 lb
Nose: 162 lb
Total Empty Weight: 764 lb

The previous empty weight was 743 lb, so the airplane is now showing approximately 21 lb heavier overall. I am not aware of any equipment additions or configuration changes that would explain that increase. In fact, the prior weighing included the wheel pants installed, while the current weighing was done with the wheel pants removed, so I would have expected the weight to be slightly lower, not higher.

The A&P who performed the new W&B indicated that it was done with empty fuel. Under the original W&B, the builder indicated that zero fuel was calibrated. Assuming both are accurate, that seems to make a fuel quantity issue less likely, but I am still trying to understand the result.

One thing that seems odd to me is that the increase in total empty weight versus the prior W&B is about 21 lb, while the difference between the left and right mains is 22 lb. That may be purely coincidental, but I’m curious whether anyone with RV-12 weighing experience thinks that pattern suggests a possible setup, scale, or measurement issue.

A few questions for those with RV-12 weighing experience:

  • Does a 22 lb difference between the left and right mains seem plausible on an RV-12, or would that make you suspect a weighing/setup issue?
  • If the prior W&B had the mains within 1 lb, would you expect a later weighing to vary this much side-to-side absent a major equipment/configuration change?
  • If the airplane was weighed with empty fuel, and the original W&B also indicated calibrated zero fuel, are there any RV-12-specific issues that could still explain both the total empty weight increase and the side-to-side main difference?
  • Are there common weighing setup issues that could create this kind of discrepancy — scale height mismatch, aircraft not laterally level, scale/tare issue, wheel not centered on the scale, brake drag, etc.?
I understand the prior W&B could have been wrong, and I am not assuming the new one is necessarily incorrect. I am just trying to determine whether this result is within the range of normal experience or whether I should request a reweigh before accepting the new numbers.

Thanks in advance for any guidance.
I would be very suspicious of this. Can you look inside the right wing? I have found much added weight to wings in the form of mud-daubers' nests.
It seems quite coincidental that the increase in weight is all on one side.
 
The right side should be heavier, the battery, oil tank and fuel tank (if an early model) help make the difference. Mine was about 14# heavier to the right before changing to the EarthX battery now the right is 9# heavier.
 
Your original weight of 743 seems low to me. How is your plane equipped? The new weight seems closer to others reported on this forum. As Seagull stated, the right side is almost always heavier on the RV-12, though a 22# differential seems like a lot.
 
The right side should be heavier, the battery, oil tank and fuel tank (if an early model) help make the difference. Mine was about 14# heavier to the right before changing to the EarthX battery now the right is 9# heavier.
Not 22 lbs. heavier!
 
You didn't mention if you had the iS or the ULS. The ULS will come in lighter overall. And if you have the ULS with the tank on the right side of the baggage compartment, that could make a difference too. Especially, if it wasn't truly empty when weighed.

On my iS there was a two pound difference between the right and left. For reference, several other weights are listed in this thread (https://vansairforce.net/threads/empty-weight-comparison.239183/)
 
My RV12 "Classic" at completion - not painted, fuel completely empty (drained at gascolator), otherwise optioned out (dual Dynon HDX, A/P, interior carpet, wheel pants)
Left Main: 300.5 lb
Right Main: 308.9 lb
Nose: 150.4 lb
Total Empty Weight: 759.8 lb
 
I recently had a new weight and balance performed on my RV-12 and wanted to ask the group whether the results seem reasonable.

The prior weight and balance, performed several years ago, showed the left and right mains within about 1 lb of each other. The new calculation shows a 22 lb difference between the left and right mains:

Left Main: 290 lb
Right Main: 312 lb
Nose: 162 lb
Total Empty Weight: 764 lb
I tried to build my ULS light, and with no fuel, no interior other than seats, and no wheel pants I had:

Left Main: 290
Right Main: 303
Nose: 142
Total: 735.

I can't imagine why your nose wheel would be 20 lb more than mine. My friend a few hangars away also had 10 lb more on the right main than the left but I can't remember his other numbers. Do you have wheel pants?

Jerre
 
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