Gear Mount Interference

[Don]

I'm starting to fit the landing gear mount (WD-921). It appears to take most folks 5-7 hours from what I can tell from various websites, which makes me feel a bit better. Figuring out where the conflicts are and what to grind away is somewhat puzzling but I'm making progress. My question is this (and I ment to call Van's yesterday but I forgot), it appears that I need to remove some of the F-904 flange. Some websites show folks doing this and some don't. The F-904 is the main spar center section and I'd prefer NOT to do any grinding on this if I can avoid it. What's your experience - did you have to grind and has anyone actually spoken to Van's about this?

 

[Norman CYYJ]

On any of the planes that I have built I have not had to grind any material out.
Check with Van's on Monday before you get out the grinder. If something does not fit it is usually because something is not in the proper place.

 

[Don]

Interference

Norman,

Thanks. So far my experience mirrors yours. This time there's nothing left that seems to even possibly be in the way; except for that flange. There's one floor stiffener that a lot of folks have had problems with and I ground the end away so that's not an issue. It's just the weldment the spar (web and flange) and the side skin. There isn't but one way to orient the weldment so the bolt holes match and the gear leg comes out the bottom, so I'm pretty sure Mr. Murphy's not messing with me on this issue. At this point I'm going to wait until Monday and work on other things.

Are you anywhere near Hope or Chilliwack (sp?) BC? I did a little mountain flying with a very experience pilot out of Chilliwack, a few years ago and that was an incredible experience. I was staying in Hope on business and enjoyed their grass field. Soaring conditions were never good enough to warrant trying that. I dream about getting this 9A up there and trying out some of the fishing and likely a sail plane ride.

 

[scard]

Don,
You do definitely have to grind a lot of the 904 spar flange in order for the gear mount to fit in the 9A. I did exactly that and all is well. You actually grind so much that you come very close to one of those flange/skin rivets.

 

[chunt0]

I had to grind away quite a bit on my 7A. The picture shows the right side--done before installation in the airplane.

 

[wpisar]

Don,
You gotta grind the f-904 for the weldment to fit and its a lot more grinding that you might think. Check some builders web sites for photos. Its ugly but its gotta be done for a good fit.

Bill P. - attaching the H/S

 

[cytoxin]

same deal on the seven

some overdo it but it will come awfully close to one rivet. i am pretty sure this is in the text as well. good luck.
p.s it wont go in w/o grinding the flange as shown in the previous pic.

 

[mikehoover]

Cut the gear leg hole in the bottom fore skin first

Hey Don,

If this is what you are asking about, I cut my gear leg holes in the bottom skin using the pattern on the plans before I put the skin on the fuse, then, once in place, I used a fluted cutter in my dremel drill to cut the material from the 904 spar and center bottom skin using the "fore skin" hole as the guide.

http://www.aclog.com/rv-9a/images/Fuselage/DCP_2705.JPG

 

[Rupester]

Cuts for Gear Weldment

Don,
I cutout the template from the drawings and clecoed it to the floor thru the indexing hole they give us. (You probably did the same) When I drew the elliptical holes on the floor, they indeed cut into the front flange of the center section... and get within 1/8" of one rivet ... as others have pointed out. Since doing that layout, I've busied myself with other tasks and assumed I'd have to call Vans before I did any cutting. I too wouldn't cut the flange until Vans gave me the OK.

Terry Ruprecht
Mahomet, IL
RV-9A QB fuse

 

[hevansrv7a]

On the QB..

Mine is a QB -7A (similar to -9A). You do need to make the hole in the floor big enough for the receiver to stick down through it. It does require removing some of the little flange that has rivets to the floor skin. I strongly recommend doing this after the spar is in place so you cut the minumum. Plans do indicate this, so did call to Van's, but my advice is do it a little at a time when you know exactly where everything else is. Just one opinion.

 

[Don]

Ginding the flange

The manual says nothing about this but darned if there isn't a comment on one of the plan sheets (34 I think) that gives the ok to remove enough of the flange for the weldment to fit. I wonder about my ability to read sometimes. I've been through the book and the plans many times and every now and again I find something like this that I missed....until Sunday evening. Once trimmed (and it didn't take a lot) the weldment almost dropped into place. Anyway, thanks for all the help. This board is a great place for support.

 

[RVbySDI]

F-904 does need to be ground.

I am at this point of construction as well. I also was concerned about cutting away the flange on the spar. I used the template in the plans as called for on the skins and that F-904 flange is indeed interfering with the aft edge of that hole. It will have to be ground down. I did call Vans tech support and was told that is what I would have to do in order to fit the bracket.

It seemed to me that the hole in the skins and the mounting geometry could have been moved forward a 1/4 to 1/2 an inch which would have eliminated any need to do this. Anyone know why the design could not have been adjusted to push this forward the necessary amount to avoid cutting into the spar? Would this change have upset the geometry of the weight and balance of the aircraft while sitting on the gear?

Another adjustment I had to make was on the aft end of one of the floor stiffener ribs. The inboard end of the landing gear bracket would not line up with the holes in the spar until I cut away approx. 1/8" of the aft end of the floor stiffener angle on the passenger side where it butts up against the spar. Once I did this the bracket sat in place correctly with all the holes lining up.