W&B modification

[Houman]

I will be redoing the full interior of the Rocket next month, removing all the carpets on the sidewall and all.

Most of the work will be done by me and Bruce ( Spatial Interior ), but signed off by a mecanic

I know I need to keep track of the weight removed and then put back, but I was wondering what would be the most efficient modus operandi ?

I was thinking of getting a somewhat precise scale, weight everything removed and then weight everything put back in and go with that... is there a better way ?

Do I have to also document how far from datum were items removed and put back ?, or is that way over the top ?

[Openwheeler3]

Haven't been through this myself but maybe it will be of less hassle and more accurate to just re-weigh the entire airplane once you are finished.

[cliffy]

The operative word here is  "W&B"    If the weight changes the "balance" changes. Both must be accounted for.

One way is to check weights on each item separately (each seat, each side wall, etc) before and after. The "Arm" of each item is in your POH and your A&P can figure the new Empty CG from that.  

The best way (especially if your plane hasn't been weighed since it left the factory) is to do a real rewieigh. More than likely you have gained in empty weight and lost in payload BUT not always. I reweighed mine after 45 years of computations only and lost 90 pounds of empty weight and gained it in payload.  Mine actually had a mistake in the original factory weights. 

[Guest]

Cliff is correct, just reweigh the plane, you'll never be able to calculate the change accurately.

Clarence

[Openwheeler3]

I guess I should have been more specific. For me, re-weighing the aircraft implies that the empty CG is recalculated as well.

[Yetti]

What are you using for the carpet panels?   Kydex over nylon carpet?

[47U]

I've never heard of the interior as having an arm associated with it, but if you laid out all the removed interior pieces in relative position on a sheet of plywood, it wouldn't be hard to slide a fulcrum under the sheet and figure out where the balance point is. Or you could just weigh each end of the sheet and calculate the balance point that way. Look to see what the piece of interior is on the balance point and measure back from the datum to the where that piece of interior would be installed on the aircraft and there you have the arm for the removed interior.

Mark the location of all the old interior pieces where they lie on the plywood, then replace each old piece with its respective new piece, see where the new balance point is, and you've got the new arm. Compare the total weight of the old interior to the new interior, and you've got everything you need to calculate the weight and balance change.

I'd run this idea past the person who is going to sign off the weight and balance change. They might call you nutty.

[Houman]

What are you using for the carpet panels?   Kydex over nylon carpet?

With Spatial interior design side panels, we don't need carpet on the sides...

here is a link : http://www.jaegeraviation.com/sinteriors

[Houman]

Cliff is correct, just reweigh the plane, you'll never be able to calculate the change accurately.

Clarence

I guess this is something that is done by a mecanic, right ?, since I don't have any equipment to do that...

[jetdriven]

You know the devil you got, just be sure you can live with the devil you may get, namely up to a 120 lb decrease in useful load.

[Openwheeler3]

Let us know how the install goes. I've been looking into the same product.

[Houman]

Let us know how the install goes. I've been looking into the same product.

Sure, will write a pirep on the experience, but from the pictures and others who have installed this, the end result will hopefully be something I can be proud of...

[cliffy]

Your empty weight might go up (most likely outcome) or it might go down like mine did but you'll know for sure where you are in relation to exactly calculating your Max allowed weight. "Interiors" don't have an arm but seats do and side walls can be calculated just like adding any other piece of equipment to the airplane. Anything that changes weight changes the CG. A reweigh is done by an A&P with certified scales. The procedure is contained in AC 43.13 

[Houman]

Well the aircraft went trough the import process last year, so the W&B were redone at that time. I'm hoping with eliminating the sidewall carpets, it would reduce the empty weight, but the new seats with headrest and armrests might even that out...

[Guest]

If the plane was reweighed at the import, have the same shop reweigh it after the new interior. It is the only way you'll get the exact change.

Clarence

[orionflt]

You know the devil you got, just be sure you can live with the devil you may get, namely up to a 120 lb decrease in useful load.

it's really not a 120lb decreasei n useful load what you have is an accurate accounting of your aircrafts weight. this helps you from overloading your aircraft by 120lbs.

Brian

[mikesalman]

Does anyone know about how much it would cost to re-weigh an F model?

[cnoe]

Following a tank reseal on a partnership E we paid $450 in Ft. Lauderdale to have a new W&B done. Tanks were already empty so it made it easy.

That was in 2013 I believe.

Cnoe

Sent from my iPad using Tapatalk

[cliffy]

Haven't done mine in a few years but $450?   I'm going out and buy scales and go back to work at that rate. Yikes!

I don't think I ever paid over $250 for a SE plane (but several years ago). 

[StinkBug]

I'm having my plane weighed tomorrow. Looking through the past logs I find that the last W&B was when a 3 blade prop was installed in 2009. It has a 2 blade prop on it now. There was also no entry for weight change when the 430 and other panel items were installed. Personally I care less about what my useful load is on paper, than what my actual weight is on takeoff.

 

For as much work as you're doing to the interior, and how difficult it will be to figure out weight and station on each piece, I'd definitely just have the whole plane weighed. 

 

I didn't get a precise quote from my A&P but when I first asked him about putting the thing on scales he threw out a number a lot closer to $100 than $450. I'll let you know exactly after I get the bill. 

[Houman]

Ok, but is this done with the tanks empty I guess, that means I have to drain the tanks ?

[orionflt]

you can weigh the aircraft with either empty or full tanks, the key is knowing the quantity of fuel in the plane. if the plane is empty the calculations are straightforward, if it is full of fuel then you have to subtract the weight of the fuel as part of the calculation. if you do not have full tanks then you do not know exactly how much fuel is in the aircraft making it difficult to make the correction for the fuel.

 

Brian

[cnoe]

Yes, the procedure is outlined in the POH. You can do it empty or full.

 

And absolutely $450 was TOO expensive for the W&B procedure, but then again it was done at KFXE where NOTHING is cheap. The price was paid more for convenience than anything but still the "correct" procedure requires 3 scales and some precise measurements. It's not something that can be done properly in an hour.

 

Cnoe

[Guest]

Starting with a defueled aircraft. Assume that they have to jack the airplane, lower it onto the scales, check for lateral and longitudinal level, raise, adjust, lower and recheck several times, use plumb bobs to measure distances, take the scale reading and calculate the empty weight and new C of G location, type it up in some form of legible document, make a log book entry reflecting the new weight and C of G, submit it to FAA? Jack up the plane, remove the scales and return all of the equipment.

Clarence

[StinkBug]

They shouldn't need to measure any distances, as there is only one empty CG. 3 scales, one under each tire. Take total weight, and figure the difference between the main and nose gear to figure where that CG is. Don't think anything needs to be submitted to FAA, but they do need to figure the new empty weight, arm, moment, and usable load and put that on paper. It's not terribly complex math, and each manufacturer has a published procedure.

 

Depending on the manufacturers instructions jacking may not be necessary either. I'll ask how they did mine when I'm back at the airport again.