SERVICE BULLETIN 14-08-29

[Bill.Peyton]

Scott,
I agree with Vic.
My concern is as the elastomer donuts contract, space develops between the donuts and the weldment when it is unloaded in flight. I have had this happen twice in 300 hours, and had to insert shims to remedy. You can here it rattle during taxi. When this occurs, my concern is that the edges of the new plate insert will rub on the 4 tubes going into the current bracket. We can see this as currently evidenced by the elastomer metal washer today. I do agree that adhesive in between the new plate and the old one may not be the right answer, but using a thin enough layer might prevent this situation from occurring I don't have the answer other than to weld the new reinforcement plate even on the non-cracking mounts.
Did engineering look at this situation Scott?

[rdoerr01]

I completed the no-crack SB on my RV-10 this morning. I painted the plate yesterday and let it dry over night. This morning I put a small ring of red RTV on the plate half way between the inner circle and the outer edge. I stuck this into position to ensure the plate doesn't come close to any of the engine mount tubes at the corners. Then I lowered the airplane and a little of the pro seal squeeze out the side. Cleaned that up and then install the top cap with a single washer spacer.

I like Vic told Van's that it needs some way to stop the plate from vibrating around and destroying the engine mount tube and they agreed, but didn't really suggest anything.

Thanks

Ray Doerr
N519RV (1140 hours)
40250

[rvbuilder2002]

Originally Posted by Bill.Peyton

Did engineering look at this situation Scott?

Yes, it was looked at.
That is why my previous post mentioned

Originally Posted by rvbuilder2002

If the doubler is installed without welding (as done in the case of no cracks found) and is installed as prescribed, with some compression pre-load on the elastomers even when the nose gear leg is hanging free, and it is maintained in this state;

Yes, it will take some effort on owners part to occasionally check for loss of preload in the nose gear elastomers. It has always been a design intent that there not be play in this location. It is in fact possible that some level of play can have contributed to damage in some cases.
N410RV went almost 2000 hrs using the originally installed elastomers, but it did require some periodic adjustment by adding an additional spacer washer.
The need for that periodic check should probably have been better conveyed to those with flying RV-10's. As a result of the continued airworthiness program for the RV-12, I think we are beginning to do a better job with that type of thing.

[RV10inOz]

Ours is welded in about now??.new bits going in this afternoon

Hopefully flying tomorrow!

I will post pictures later.

[rvbuilder2002]

Originally Posted by rdoerr01

I like Vic told Van's that it needs some way to stop the plate from vibrating around and destroying the engine mount tube and they agreed, but didn't really suggest anything.

Actually Van's didn't agree, which is why the NOTIFICATION was issued without that recommendation.

Since you used some RTV (or proseal? you mention both...), report back at your next inspection and let me know if it is still holding the plate in place or not.

[RV10inOz]

All went together really well. The aviation welder did a beautiful job. Fixed a cracked step too!

I forgot pics today but I will be zip tie crazy in the morning tethering all the wires, and I will take some then.

Only problem has been the extra nose height gained from new rubbers, new nose wheel tyre (higher quality one is bigger in diameter) and the extra thickness has dropped outr? tail down. The Comanche now will not pass its stabilator under our tail.

Ohh well??time to fix that problem. But it is a good problem to have.

Total man hours to date;
Strip down and have ready for welding 10 hrs.
Welding repairs 4-5 hrs approx.
Reassemble 9 hrs.
Tidy up and re cowl and paper work estimate 3-4 hrs.

All up about 27-28 hours I guess.

The fix with the spacer ring looks really solid. I assume that the doubler insertion actually achieves the same result.

[vic syracuse]

Yes, I noticed that the nose sits a little more proud now. I measured it at about a 1" gain. Mine has both the new plate and the doubler. I noticed it as well when I was cleaning the vertical fin, as I could reach up quite a bit higher.

And it sounds much more solid when taxiing now, too.

Scott, I did religiously make certain the elastomers were tight. I had 4 of the washers in mine. I see now that the service bulletin recommends replacement when 3 are needed.

Vic

[rvbuilder2002]

Originally Posted by vic syracuse

Yes, I noticed that the nose sits a little more proud now. I measured it at about a 1" gain. Mine has both the new plate and the doubler. I noticed it as well when I was cleaning the vertical fin, as I could reach up quite a bit higher.

And it sounds much more solid when taxiing now, too.

Scott, I did religiously make certain the elastomers were tight. I had 4 of the washers in mine. I see now that the service bulletin recommends replacement when 3 are needed.

Vic

I think the recommendation is to replace if you need MORE than 3.

[vic syracuse]

Yep, more than 3.

Vic

[TimO]

I did my SB work this weekend too. I ended up using a thin layer of RTV but did it over the entire surface, and then jacked the back end up so squeeze everything out that I could. In the end, there is really almost zero gap between the 2 plates, and there shouldn't easily be any moisture that gets in there.

I believe the SB should prevent much worry about that particular part breaking, but I do have one area of concern that will linger.

The shaft that the elastomers ride on, directly contacts the hole in the engine mount. The doubler is slightly larger, so there won't be an issue with that.
But, when you look at the shaft, right at the top of the topmost elastomer, one side of my shaft was chafing on the hole of the engine mount. This led to a slight thinning of the shaft in one area. One other thing I noticed is that the shaft had a bit of rust inside.

I believe that: 1) people should prime (NOT liquid plumber, but liquid PRIMER) the inside of that shaft before initial assembly.

2) That shaft won't last forever. At 1070 hours, it's showing wear. I'm sure it'll go 2000 hours. But, since this thing was designed with no replaceable wear surfaces, it won't last forever. I would love to see a sleeve over that part of the shaft, that can be replaced, but doing so would require that the elastomers were made with a larger hole, and the tophat shaped retainer would have to be wider too. So this isn't likely to be an easy thing to fix. So, I think people are going to have to pull that shaft and inspect it (I'd recommend maybe a 500hour inspection at least) and replace as necessary. On Van's end, I'd hope that they keep a dozen of these in stock, because it's going to be considered a wear part on higher time RV-10's. I don't know what that part costs, but it would be nice if there was some sort of bushing there to protect it...either on the hole side, or the shaft side, that could be replaced.
Tim