Elevator Bellcrank Alignment

Aero_Octaveus · #1 02-10-2019, 04:34 PM

Long winded issue here....
Anyone have issues with the alignment of the Elevator Bellcrank F-635 not being perpendicular to the longitudinal axis of the plane?

I'm currently working on the F-706 bulkhead and when I've drilled the 1/4" holes for the bellcrank in the F-728 and F-729 webs/angles, (See Dwg 26) the axis is not parallel to the F-729 rib. Axis is off by about 1/8" putting the bellcrank on quite an angle.
http://4.bp.blogspot.com/-zM-OIuMXJn...0/IMG_0981.JPG
I called vans and their suggestion was to re-drill the holes and add doublers. Since I'm so early in the fuse build, I decided to re-build F-706 bulkhead assembly again. On this second attempt. I haven't drilled the 1/4" holes in the F-728B and F-729B angles yet, however initial measurement of the Factory punched holes looks to still be out about 1/16" with everything built up on the second bulkhead.
http://4.bp.blogspot.com/-aeRR3OF8en...0/IMG_1089.JPG
Should be easy enough to spilt the difference and move one hole forward 1/32" and one hole backward 1/32".

What I'm thinking of doing is avoiding drilling the 1/4" holes in the angles/webs until the Fuselage is more assembled (Just before I have to rivet in the F-728 assembly) My thinking is this scenario will help ensure that the axis bolt can be drilled perpendicular to building lines with certainty.

Any thoughts or opinions?

Anybody have any experience with this?

Tankerpilot75 · #2 02-10-2019, 07:29 PM

Quote:

Originally Posted by Aero_Octaveus

Long winded issue here....
Anyone have issues with the alignment of the Elevator Bellcrank F-635 not being perpendicular to the longitudinal axis

I?m probably unqualified to speak to this issue since I didn?t build my RV7A but instead purchased it off the original builder. However,

When I bought my RV the trailing edge of the two elevator sides differed by over 1/2 inch. This caused a severe rolling motion about the central axis of the aircraft. I was aware of the misalignment before I bought the RV (it was quite noticeable) but was caught totally unaware of the severity of the roll rate it caused until I flew the RV to its new home at higher cruise speeds. It kept trying to roll me upside down!

The problem was caused by the two bell cranks being drilled ?even? and not drilled so that the trailing edge of the elevator was ?even.? Hired a sheet metal expert who welded the old holes closed and then redrilled the bell crank holes so that the elevator?s trailing edge was perfectly aligned. Evenness of the bell crank can lead to a misaligned elevator. Make sure your elevator is properly aligned before you drill the holes.

wirejock · #3 02-10-2019, 08:05 PM

I don't recall having an issue drilling the holes. You could release the clekos, drill the holes, bolt it with a bushing spacer then cleko the structure back together.
Hopefully the rivet holes won't be off.

PilotjohnS · #4 02-10-2019, 08:30 PM

Well shoot I am there right now. I guess I will look out for this. Thanks for posting.

Update: just checked and mine is fine.

rvbuilder2002 · #5 02-10-2019, 08:34 PM

Quote:

Originally Posted by Tankerpilot75

The problem was caused by the two bell cranks being drilled ?even? and not drilled so that the trailing edge of the elevator was ?even.?

The elevator bellcrank is the part directly behind the baggage bulkhead the induces the elevator push/pull direction reversal..... the parts on the elevators are referred to as the control horns.

I don't think the bellcrank mount bolt holes being misaligned fore/aft by only a 1/16th of an inch will be a problem.

Tankerpilot75 · #6 02-11-2019, 08:14 AM

Quote:

Originally Posted by rvbuilder2002

The elevator bellcrank is the part directly behind the baggage bulkhead the induces the elevator push/pull direction reversal..... the parts on the elevators are referred to as the control horns.

I don't think the bellcrank mount bolt holes being misaligned fore/aft by only a 1/16th of an inch will be a problem.

My bad. Like I said I didn?t build my RV. Just had to repair a build issue that caused a severe flight problem.

gasman · #7 02-11-2019, 10:42 AM

Can drilling this location wait till the parts are in their final (riveted) position?

Aero_Octaveus · #8 02-11-2019, 11:33 AM

Quote:

Originally Posted by Aero_Octaveus

What I'm thinking of doing is avoiding drilling the 1/4" holes in the angles/webs until the Fuselage is more assembled (Just before I have to rivet in the F-728 assembly) My thinking is this scenario will help ensure that the axis bolt can be drilled perpendicular to building lines with certainty.

Well that's what I was hoping to do. I haven't seen a build log that someone has done this on, and since its different from Van's Instructions. I figured i'd try to gather some intel before I forge ahead breaking new ground.

motodave · #9 07-20-2019, 07:32 AM

Just got to this point and have same issue, built to spec per plans (riveted together) and holes don?t line up! I inserted a long .25 bolt to see alignment and disappointed with result unless once it ?aligns? itself when attached to the skins....it is a flimsy structure at this point. I?ll build other parts while I wait for tech support to return from Oskosh. I hope I don?t have to reorder the bulkhead as it was a fair amount of work.