RV-7 Horizontal stab attach questions

[Doyle231]

Hi all,

So I've purchased and rv7 QB kit locally that previous owner didn't finish. I'm looking to start at the tail and have the following questions for attaching horz stab.

1-location of the fwd spar attach holes can be seen in F-781 view c-c but don't give measurements from above only front on. Are the holes drilled thought deck then back drill them through front spar angle/shim/longerons?

2 - Rear spar attach bars are blank and rear spar of already completed horz stab has 4 X rivets yet to be drill. How will one locate holes for rear spar to attach bars

Please find attached pictures of plans that detail


https://c1.staticflickr.com/9/8361/2...b6dc4486_q.jpg
https://c1.staticflickr.com/9/8885/2...028dbd47_q.jpg

James
Australia

[Arie]

G' day mate
Let me try and answer your questions.
1. The exact locations for the attach points points for the horizontal stab front spar angle holes might not be specified in the plans because no two are exactly alike. What you need to do is ,place your stab on the fuselage and make sure it is perpendicular to the lateral centre line of the fuselage ( the instructions tell you how to do it) and that it is parallel to the longitudinal axis of the fuselage ( there are numerous ways to do this), After you have done that ,then clamp it down in position. You then need measure and tripple check every thing, and then drill the outboard attach holes through the H/S attach angle , the shim , aft deck, longeron and the angle on the F710 bulkhead in a location that will give you EDGE DISTANCE IN ALL LOCATIONS!!. To drill the two inboard holes on the H/S attach angle you would need a 90 degree drill and their location are easily determined from the plans.
2. The " vertical" bars on the F711 bulkhead that attach the aft spar of the H/S to the fuselage should have two size 30 holes in them. If not ,the locatation for those two holes are on the plans .With every thing clamp down you could just use those two holes in each "vertical" bar and back drill into the aft spar of the horizontal stab.
Hope this helps.
Regards
Arie

[JonJay]

Arie has provided and excellent explanation. He emphasized the edge distance concerns. This is a huge problem area and I suspect many flying RV's out there are doing so without adequate edge distance for the holes through the longeron. I hear about them all the time. Very common mistake.

[Doyle231]

thanks Arie!

The first picture details the measurements i believe are the ones required to drill the 2 x holes that will attach the rear spar and bars. Is it a safe method to back drill through these into spar? also once the measurements have been established on the upper deck how would you recommend transferring these to the front spar attach angle? I've received an email from vans stating - James, The attach holes should be in line with the rivets on the upper HS 710 and 714 bars (may not necessarily be exactly centered between existing rivets, however) ?. And ?. Centered on the F-711C bars.

thanks james

[Doyle231]

also once the upper deck has been marked any hits on transferring marks to fwd spar angle. is it just one of these '' make edge distance on spar attach angle and drill deals'' ? the plane state position as viewed from front to rear but not from above so no rear measurements for attach angle.
https://c2.staticflickr.com/8/7577/2...e7d77c86_q.jpg