What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Small elevator pushrod installation

Airhead

Active Member
Question about 7A QB. I am probably missing an important instruction (surely) somewhere. I made all the pushrods as called for on Sht 38 of the plans. When I went to install the elevator bellcrank and pushrods, I find that the small F-789 pushrod cannot be inserted into position from either end without interference from the bulkheads. It appears to be aout an inch too long to insert from the rear, but before I drill out the rivets for the rod end bearing on one (or both) ends I thought I would ask where the plans said to assemble the rod ends with the rod in its position in the fuselage, or is there some other majic to this?
 
Take the bearings off and stick one threaded end thru a wiring hole and it will go in. It is very close but it will go. Not sure it is possible with the bearings on....
 
Thanks for the reply. I have taken the rod ends off, but when I slip the pushrod through the 706 bulkhead (at the bellcrank) and slide it forward until it hits the bottom of the 705 bulkhead, it still sits on the top of the 707 bulkhead (to the rear of the bellcrank) and therefore can't be raised into the wiring hole at the top of the 705 (without bending something). After trying it again I am convinced I need to remove the threaded part of the rod bearing from the tube (i.e. drill out the rivets).
 
I can't remember the exact way it can be done... I know it was very tight. If it is built per plans it will go....I do remember having to remove the flap motor box braces.
 
Relieve the upper side of the hole in the 706 BH

Been there, done that. Relieve just enough material from the upper side of the 706 hole to let it slide in (I just kind of radiused mine). Not sure where I picked that up, it was either from builders or Vans. Either way, I have talked to several now who have done that.

Thanks for the reply. I have taken the rod ends off, but when I slip the pushrod through the 706 bulkhead (at the bellcrank) and slide it forward until it hits the bottom of the 705 bulkhead, it still sits on the top of the 707 bulkhead (to the rear of the bellcrank) and therefore can't be raised into the wiring hole at the top of the 705 (without bending something). After trying it again I am convinced I need to remove the threaded part of the rod bearing from the tube (i.e. drill out the rivets).
 
Do not remove the riveted end ...

... like others said, you must remove the threaded rod end (from one end at least) and it will go in from the aft end forward. I can't recall precisely how ... or thru which orifice ;) it goes, but it eventually it went into the tunnel. Most of us did a lot of headscratching about that ... just like you are.
 
These responses are correct. Do NOT drill out the rivets. It will be very difficult to re-rivet in place.
It will go in with the threaded ends riveted on!
Literally thousands have been done.
 
Last edited:
Thanks for the help. I will try relieving the 706 hole on top a bit as Roger suggested. It is very close and a little bit might work. Am glad to get these suggestions before drilling out the rivets. Everything starts out easy....thats always just before it gets difficult.
 
Side Comment ...

I have tons of respect and admiration for the Vans organization, but this is one of several dozens items where one sentence in the instructions could save hundreds of people (thousands?) a LOT of time. I've found at least 20 instances where that's the case. Just a few words added to a Word document could make all the difference.
OK, I'm done baying at the moon now. :eek:
 
After looking at and pondering the situation for a spell, I see that enlarging the 706 hole at the top is not really a great option. Since the forward end of the rod (just the threaded tip, rod end removed of course) must be raised at the 705 hole about 1-1/2 inches to enter, and the pivot point is the 706 hole which is approx. midway between the 705 and 707 bulkheads (the rear of the rod threaded tip is resting on the 707), the top of the 706 hole would need enlarging about half of that, or 3/4 inch. That would take me into the upper line of rivets. Before I do that I would rather try to get the rivets out and remove one end or remake the entire pushrod. It certainly seems that a note on Sht 38 to wait and rivet one end after the rod is placed in the tunnel would have been greatly appreciated by many.
 
Again ....

... removing the rivets is not necessary. You just haven't found the right contortion/position of the p-rod tube.
 
Bob,

Do what you want but if that rod is made per the plans, it will go in.... Hundreds before you have gotten it in. If you try to rivet that end on while it is installed, you are in for a real treat!!!

I wish I could remember exactly how I did it. I had mine in and out a few times.
 
Brantel and Mel,

Please elaborate on the diffuculty in re-riveting one end of the p tube in place. Since these are blind rivets it would seem that one could just rotate the tube and put the rivets back in from the top position. of course getting the old rivets out could be the problem. Others have suggested the right "contortion" of the tube, but the reality is that the length of the tube (threaded tip to threaded tip) is a little more than the distance from the 705 to 707 bulkhead, meaning, until it goes thru the hole in the 707 its not going to drop into the tunnel. The only contortion that would do it is to bend (or hopefully "flex") the tube enough to get it thru the hole. If this is possible without a permanent bow in the tube I will indeed be suprised. However, I have already been suprised once when the ##!&# thing didn't fit in the first place.
 
From my standpoint, I don't remember using pulled rivets for this application. I remembered them being solid rivets.
Regardless, I would continue to search for the problem because, even though this has always been a tight fit, thousands of RV have been built without having to build the pushrod in place.
I'll go out and look at the plans later today and see if I can see the problem.
 
We just put in a little relief on the top of the hole in that rear bulkhead (baggage compartment bulkhead, whatever number it is).

I didn't like "flexing" the pushrod, and there's plenty of "meat" on that bulkhead around the opening, so no issues with edge clearances anywhere. It only took a little bit of sanding the top of the opening to "doghouse" it.
 
....meaning, until it goes thru the hole in the 707 its not going to drop into the tunnel.

You lost me here. My plans show no hole in 707. 707 is the bulkhead behind the baggage bulkhead (706).

I'm sure you have checked and rechecked you dimensions over and over, but I can't re-iterate enough that it has been done many, many, many times in the past.

Do you have an EAA tech counselor close that could verify the problem. It's SO very easy to overlook something when you are so close to the project.
 
I took off the removable ends, protected it all
with shop rags and 'flexed' it in.
It isn't made of glass.
Tom
 
As others have said, it will go in without doing major surgery. Keep fiddling with the up/down & left/right angle and as of a sudden you'll wonder what the problem was.

I swore mine wouldn't fit but after I got it in the first time, I had no problem removing and re-installing later. In fact, I didn't like the number of threads I had engaged in the rod ends, so I made another about 3/8" longer and got it in.
 
Last edited:
Thanks guys. I do have some resources at nearby Spruce Creek including an EAA tech and others that are building/flying RVs. I think before I bend, spindle, or mutilate my tube I will see if I can get more input. I have triple checked the plans vs length (45-15/16" tube length) and fiddled with it for several hours. It ain't going without considerable grinding or flexing. Maybe I got "shorted" on my QB fuselage and what I need is a plane stretcher.
 
OK, she's in. Thanks Tom, I just needed the courage to "flex" my muscles. I played around with the tube out of the plane for a few minutes flexing it like you string a bow. Decided it just might take that much flex without deforming. Wrapped the center where it goes through the 706 hole with several layers of duct tape, taped the treads on both ends (they get raked over the bulkheads), and flexed. It was so tightly flexed I could barely get it to move forward, but with a little twisting it moved forward an inch or so and popped down into place. Whew, that took all day. However maybe it wasn't all in vain because there was no recent post I could find addressing this problem. Now there is. Thanks all.
 
No force, no flex NEEDET!

Hello Bob

Maybe I'm allready to late?!

I was over lunch time at my building place and checked the situation.

You do not need any flex or force to put in the controll tube. I made a serie of pictures (step by step) with my mobilephone, how to insert the tube with just two fingers and no force.

Now I have to work, I will post the pictures when I'm at home this evening.

I hope it will help others also.

Reagrds,

Dominik
RV-7A
Switzerland
 
Dominick,

I would like to see your method because I may need to remove the tube at some point (it seems everything else has to be fit and removed several times beore your done), and others hitting this point in construction could benifit. There must be majic in those two fingers.

Bob
 
Step by Step

Hello Bob
here are my pictures. Sorry about the quality, I made them with the mobil phone.

I made my tube by 1/8" longer, I like to see a few threads more engaged, so I was really alarmed when I have seen your first post!

* I slided the tube in from the back to the front
* on the right side, along the bellcrank channel F-728
* throu the rear spar bulkhead F-705 bulkhead, untill it hit the main spar web,
* then back throu the bulkhead F-706B until it sits on the correct position.

I hope all is fine with my controll tube, because I can really put it in with 2 fingers!? So please check my methode and report, so that I can go relaxed to bed :rolleyes: and not have to fight against bad dreams :)-)

Tube 1.jpg


Tube 2.jpg


Tube 3.jpg


Tube 4.jpg


Regards,

Dominik
RV-7A
Switzerland
 
Last edited:
Dominick,

You have provided a great end to this post. Your pictures say it all. I just didn't think outside the box...literally, it just didn't occur to me to go outside the center support at the bellcrank bulkhead. There is a couple more inches between the 706 bulkhead and the main spar than between the 707 bulkhead and the 705 bulkhead. Even though I have already "flexed" mine in, I think I'll take it out, paint the scratches and PUT IT IN RIGHT. Sleep well.

Bob
 
small elevator push rod

Remove a little material in the tunnel at the top and take the rod bearings off. It will fit from back to front with a little angular persuasion.
 
Thanks

Thanks for the photos Swiss Eagle. I know this is an old thread but the photos helped a bunch. I had no idea how to get the push rod in and was thinking about trimming the bulkhead when all I had to do was step back and think a little. This site is great!!!
 
Hello John
Great that my pictures still helped!!!

After you installed the tube, check clearence at the rear-spar bulkhead. At nearly all RV-7, the tube is touching the rear spar. It is ok to grind the spar there in height by max. 1.6mm. PM me if you need a picture.

Build on ... you don't know what you are missing ... bring it to fly and enjoy this dream machine!

BR, Dominik
 
Hi John
still looking for the pic ... I knew I have one ... sent is also to a buddy ... but no luck in finding it. Sorry!
 
Another satisfied customer!

Thanks for the photos Swiss Eagle. I know this is an old thread but the photos helped a bunch. I had no idea how to get the push rod in and was thinking about trimming the bulkhead when all I had to do was step back and think a little. This site is great!!!
Thanks Dominik, your pictures and process helped me too!

Dave
 
F-789 Elevator Control Rod

Doesn't help if the baggage panels are already riveted on. I had to flex it.
 
Not Really ...

Baggabe floor panels are open in the center ... and the opening is the same. Even with a finished plane, you can take this tube out if you need.
 
I know this is an old thread, but I just tried to install my F-789 today. I realized I needed to remove the rod end ball joints and I was able to get the control rod into the center tunnel. I then went to install the forward rod end. I was surprised that it only threaded on about a 1/2". I thought normally we would want to use half of the thread of the male portion. Is this normal and ok?
 
Oh my gosh

Well, I havent put this push rod in. I have been doing final assembly. I have already installed the aileron trim servo, and stuff.
After reading this thread, I am afraid I will have to do some de building to get this tube in. I figure I might as well do it now before it gets hot(ter) in the hangar.
Thanks for refreshing these posts.
 
The aileron trim servo isn't a problem. You have to install it from the aft direction. I already have my autopilot servo installed as well and I was able to pass the control rod to the side of it. I did remove the 2 screws for the forward flap brace. I can't remember whether that was actually require or just part of the process for me to figure out how to install the control rod.
 
Back
Top