Elevator counterweight installed wrong side RV-8

RhodeIsland9 · #1 10-10-2018, 07:04 PM

So I managed to install the right elevator counterweight (trimmed) in the left side (and vise versa right side) during final riveting.
note: fiberglass tips are not installed

Problem is, when the counterbalance skin is riveted around the counterweight it is not easily removed. (did I mention that I also used Proseal on the counterweights).

Looking for advice on options

1. Do nothing and the elevators will still balance as a complete assembly but not individually.

2. Carefully trim the right counterweight in place and save the piece removed to bond/fasten to the left side.

3. Carefully trim the right counterweight in place and drill remove counterbalance skin install new full size weight on left side(possibly skin ribs spar if damaged during removal).

Is it important to be able to individually balance the elevators?

Champ · #2 10-10-2018, 07:50 PM

If my memory is right I think Vans recommends to balance the L & R elevator halves individually. My counterweights are bolted in per plans but this should have been done with nutplates to make them re torque able without having to cut thru the fibreglass tips to get at the nuts.

I did balance individually and had to trim the right counterweight and bolt a piece onto the left side because of the weight of the trim servo.

I don?t know that I would trust proseal to hold the counterweights on.

Individual vs combined balance has been covered on VAF before.

RhodeIsland9 · #3 10-11-2018, 05:15 AM

Quote:

Originally Posted by Champ

If my memory is right I think Vans recommends to balance the L & R elevator halves individually. My counterweights are bolted in per plans but this should have been done with nutplates to make them re torque able without having to cut thru the fibreglass tips to get at the nuts.

I did balance individually and had to trim the right counterweight and bolt a piece onto the left side because of the weight of the trim servo.

I don?t know that I would trust proseal to hold the counterweights on.

Individual vs combined balance has been covered on VAF before.

The counterweights are bolted in with nutplates, Proseal was added insurance to keep them secure. The difficulty is removing the weights to place them in the correct location.

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Robert Anglin · #4 10-11-2018, 06:08 AM

There are two types of weight installations on the 8. An older one and the newest stile that has been out for a few years now, after the up-data to total pre-punched. My only comment is that for both, I have seen a lot of none serviceable installations. Pop rivet covers and the like. It is worth it to take the extra time and install them so they can be serviced later on. Bolts, nuts, nut-plate, screws " instead of pop-rivets" and so on. If you are going to keep the aircraft for a long time, you will be glad you did, in the years to come, when you re-balance after paint or repairs. Just an idea for thought. Yours, R.E.A. III # 80888

RV6junkie · #5 10-11-2018, 07:28 AM

You have a few options. One is to disassemble and build back up as per plans. The other is to simply rebalance each elevator after they have been mated to the HS. Let?s face it, you are going to have to rebalance after paint anyway. One will probably need to be drilled and you?ll have to add weight to the other. It?s no big deal.

I-TERA · #6 10-12-2018, 02:18 AM

Easy to reduce the counterweight drilling out some lead, easy to add small ( 4X20X30 mm) pieces of lead with a big soldering iron ( not a flame welder ) and tin, hard and safe .
Claudio

BillL · #7 10-12-2018, 06:34 AM

Quote:

Originally Posted by RhodeIsland9

So I managed to install the right elevator counterweight (trimmed) in the left side (and vise versa right side) during final riveting.
note: fiberglass tips are not installed

Problem is, when the counterbalance skin is riveted around the counterweight it is not easily removed. (did I mention that I also used Proseal on the counterweights).

Looking for advice on options

1. Do nothing and the elevators will still balance as a complete assembly but not individually.

2. Carefully trim the right counterweight in place and save the piece removed to bond/fasten to the left side.

3. Carefully trim the right counterweight in place and drill remove counterbalance skin install new full size weight on left side(possibly skin ribs spar if damaged during removal).

Is it important to be able to individually balance the elevators?

It sounds like you have the flat counterweights not the ones that fasten on the leading edge. There are only a few parts to covert to the later style and it will save a lot of weight on the tail section. I seriously considered upgrading to the later style and found there are only a few parts different. What ever you do, just bite the bullet and do it right. Only a few hours difference and I have slept better after it was done. Drilling out the rivets is not an issue and the mental is always harder than the actual for me.

I had to make a new forward skin (25hrs), remove the roll bar and all the hardware under it to set 4 rivets (20hrs). Some things you just can not tweak. RVBuilder2002 (Scott) gave me really good advice, "no other right way to do it, Bill". Now flying, I don't regret either "little" project. The sting of time is gone and happy with the lasting quality.

nilberg · #8 10-12-2018, 09:09 AM

The way the plan is for the current counterweight, I would like to see a serviceable version that do not compromize the securing of the counterweight.

Right now, even with replacing the nylocks with nutplates, the led is still locked in due to the countersinked led and dimpled skin.
However, if serviceable means checking the two bolt for torque, then it seem like a good idea to have nut plates on the flange.
Would attaching a nutplate with pull rivets be a solution ? I am tempted, even if the counterweight itself is going nowhere.

RhodeIsland9 · #9 10-12-2018, 02:20 PM

The mention in a earlier post about the older flat counterweights got me thinking.

This is a counterweight from a RV-6. Installed with bolts and platenuts. It would eventually be trimmed down to replace what was mistakenly removed and make the elevator balance post paint.

I like the idea of being able to remove, trim and reinstall the weight for a perfect balance.

Would this be an acceptable solution?