Weighed my Naked Mooney Today

[Wildhorsesracing]

I have a set of scales that I use to corner balance my racecars so I hauled them down to the hangar and weighed my naked Mooney today.  I truly wish I had weighed it before I stripped the paint off.

It ended up 19.9 lbs lighter than what the various calculations have been done over the years as equipment was added/subtracted.

Here are the weights (full of fuel - 54.4 gals):

Nose: 548 lbs

Left wing: 675 lbs

Right wing: 684 lbs

Total weight: 1,907 lbs

My question is - how can I convert those to usable #'s for a W&B datum or should I just subtract 19.9 lbs from my empty weight and leave it alone?

[KSMooniac]

Your service manual has a procedure for weighing the plane. You'll need an IA to sign it off, too. The procedure involves leveling the plane, and maybe with empty tanks, full oil, etc.

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[EricJ]

54 minutes ago, Wildhorsesracing said:

Total weight: 1,907 lbs

My question is - how can I convert those to usable #'s for a W&B datum or should I just subtract 19.9 lbs from my empty weight and leave it alone?

I don't even know how to compute corner weights when there are only three wheels, and I can't find a ride height adjustment on these things anywhere.

j/k ...   Looks nice!

 

[RLCarter]

W&B is done with the aircraft level, no fuel and no oil and a plumb bob,  all the math starts there. Service Manual spells it all out, I might be able to send a copy if your plane is listed in my manual 

[MIm20c]

Just now, RLCarter said:

W&B is done with the aircraft level, no fuel and no oil and a plumb bob,  all the math starts there. Service Manual spells it all out, I might be able to send a copy if your plane is listed in my manual 

I thought it was done with full oil and unusable fuel?

[Hank]

11 minutes ago, RLCarter said:

W&B is done with the aircraft level, no fuel and no oil and a plumb bob,  all the math starts there. Service Manual spells it all out, I might be able to send a copy if your plane is listed in my manual 

No plumb bob, just a level across the radio access panel opening. How to hold it level without affecting the weight? Dunno, haven't tried . . .

[Guest]

Here is the excerpt from the manual.

 

[clh]

Total weight would not be affected, but CG is very dependent on having the aircraft at the proper "level".  The maintenance manual has a very easy to follow procedure.  Getting it level involves blocks (weight must be accounted for)  and/or letting air out of one or more tires.  It is a PIA.  FWIW, I would not "officially" weigh an aircraft unless I knew what the outcome.   You can (and usually do) lose quite a bit of useful load.

[RLCarter]

24 minutes ago, clh said:

Total weight would not be affected, but CG is very dependent on having the aircraft at the proper "level".  The maintenance manual has a very easy to follow procedure.  Getting it level involves blocks (weight must be accounted for)  and/or letting air out of one or more tires.  It is a PIA.  FWIW, I would not "officially" weigh an aircraft unless I knew what the outcome.   You can (and usually do) lose quite a bit of useful load.

When I did mine i placed the blocks under the scales for the mains, very little air had to removed fron the nose tire to get it level

[jetdriven]

That’s why wild horses has a lower empty weight. He let 19lbs of air out if the nose tire. 

[clh]

nope must have been nitrogen....

[jetdriven]

I fill mine with helium.  wings too. and I only will weigh it outside in a 20 MPH headwind. 

 

[HRM]

Is that plane-porn or what? Beautiful!

[Guitarmaster]

When you first did this, I wasn't sure how I felt about it. In fact, I really didn't like it. However, it has kind of grown on me and I really like it now! Well done.

 

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[HRM]

9 hours ago, Guitarmaster said:

However, it has kind of grown on me and I really like it now! Well done.

The weighing or the glittery silver jewell that's his Mooney? 

[RobertGary1]

Good job but you really don't have to get naked first. Might embarrass your hanger neighbors.

 

-Robert

[Raptor05121]

On ‎12‎/‎5‎/‎2017 at 6:17 PM, Wildhorsesracing said:

I have a set of scales that I use to corner balance my racecars so I hauled them down to the hangar and weighed my naked Mooney today.  I truly wish I had weighed it before I stripped the paint off.

It ended up 19.9 lbs lighter than what the various calculations have been done over the years as equipment was added/subtracted.

Here are the weights (full of fuel - 54.4 gals):

Nose: 548 lbs

Left wing: 675 lbs

Right wing: 684 lbs

Total weight: 1,907 lbs

My question is - how can I convert those to usable #'s for a W&B datum or should I just subtract 19.9 lbs from my empty weight and leave it alone?

 

Read the service manual. It calls for draining all useable fuel and oil, (I suspect a lot of heavy Mooney's are forgetting the ~15lbs in the nose they forgot to take out) then leveling and using a plumbob prior to weighing. Your A&P will need to verify then numbers and record model and serial of the equipment used to weigh the plane. My rough weights are as follows (using Arlyn Scales):

Nose: 498.0 lbs
Left: 533.9 lbs
Right: 527.5 lbs

Old empty Weight: 1,573.7 lbs
New Empty Weight: 1,559.4 lbs

Old Useful Load: 1,001.3 lbs
New Useful Load: 1,015.6 lbs

I still need to level and do CG calculations

[Marcopolo]

@Raptor05121,

 

  I'm not completely on board with the book here if it said to weigh without engine oil.  It looks to be different than all other service manuals that I have read, including mine for the K, says to fill engine oil to max which is 8 quarts prior to weighing.  I do agree with only having un-usable fuel levels in the tanks.

 

Ron

 

[N6758N]

I thought @Raptor05121 was incorrect about the oil, but I checked the FARS and was surspised to learn

"The empty weight for aircraft certificated under the Civilian Air Regulations (CAR) part 3 does not include the engine lubricating oil. The oil must either be drained before the aircraft is weighed, or its weight must be subtracted from the scale readings to determine the empty weight."

[Marcopolo]

 

7 minutes ago, N6758N said:

I thought @Raptor05121 was incorrect about the oil, but I checked the FARS and was surspised to learn

"The empty weight for aircraft certificated under the Civilian Air Regulations (CAR) part 3 does not include the engine lubricating oil. The oil must either be drained before the aircraft is weighed, or its weight must be subtracted from the scale readings to determine the empty weight."

Very interesting, I sit corrected...once again.  Wonder where it changed, as mine is weighed with it in, not drained, and asked for max fill.

 

Ron

[N6758N]

15 minutes ago, Marcopolo said:

 

Very interesting, I sit corrected...once again.  Wonder where it changed, as mine is weighed with it in, not drained, and asked for max fill.

 

Ron

Probably FAR 23 certificated aircraft versus CAR 3...

[Raptor05121]

You are not the only one surprised. I read the service manual to the letter and even called someone and asked about the oil thing. Odd, but its true. I also think its a CAR3 stipulation. But aren't the newer Mooney's still under CAR3 with the 2A3 certificate?

Either way, that's 15 lbs a lot of people are probably losing and not aware of! And looking at my old vs new empty weights, that could account for my 15lbs weight loss. So in some cases...it might be beneficial to do a new W&B.

[Guest]

The difference in oil in or out is whether you’re doing a licensed empty weight or a basic empty weight.

Clarence