Trent's RV14 Build: 11-02 -> 11: Empennage Attach

Attaching the empennage began by checking over the previous elevator rod end measurements. I noted that there was still a very slight amount of rubbing so checked the elevator eyebolts again to relieve the slight rubbing - and checked the rod ends again with the camera. I am happy i now have the correct number of threads showing, and there is zero rubbing - right up to the limits of travel.

I checked the limtis of travel again (as individual elevators)
L ELEVATOR: 38 UP and 27 DOWN
R ELEVATOR: 37 UP and 30 DOWN

Drilling the Elevator Horns

I started this step with the left elevator installed, and the counterbalance arms held flush with the skins.

Next up was to reduce the diameter of the "E-Drill Bushing" slightly so it fitted in the centre bearing, and i found i also needed to drill it out slightly to #30. I Then made up some simple spacers to fill the gap between the horn and the centre bearing bracket, installed the bushing and drilled. The bushing wanted to spin of course, so it was a bit of a 3 handed job, but if you go medium speed and pull the bit out the clear the swarf it worked ok.

This gap must be fileld with a spacer

Reducing the size of the "E-Drill Bushing". Not much was needed.

These were the sppacers i settled on (there are 2 to clear the rivets).

Clamped and bushing installed ready for drilling.

First hole drilled.

Once the left was drilled, i repeated the procedure for the right elevator. I then installed the called out hardware, and needed the following hardware to fill the gaps. The left and the right differed by one thin washer thickness only. I don't really like the Van's steel washers as i can see they are rusting already - i will need to look into getting some large cad plated washers instead - the steel ones are also very very thin and bend easily - doesn't feel like an aircraft part to me.

No time like the present....

I have been thinking about this step for a long time - it's one of those that you just have to do - yet if you stuff it up can mean a major revisit to the project (like rebuilding a new elevator, or at least welding the wrongly drilled hole in the horn!).

So - no time like the present.

In setting up the elevators for drilling, i mounted the elevators with both counterbalance arms clamped in the "in trail" position. I ran a string line from the end of one elevator to the end of the other (right in the middle of the trailing edge of both) and noticed that both inboard trailing edges were sitting slightly high. I then held the string in my hand, and made sure it ran true down the left hand elevator trailing edge, and unclamping the right elevator and moving it, found there was no position where it ran true down the right hand elevator trailing edge as well (and vice versa). So somewhere in the system is a little bit of twist or out of tolerance. Having read heaps of blogs, i decided to follow the plans and clamp the counterbalance arms in trail, and drill the horns in that position.

I first measured as per the plans, and the right horn ended up being BOTH the AFT most and UPPER horn, so this was drilled to #12 first. I then fabricated a spacer block, put it in position using a bolt, clamped it and drilled the left horn.

In the end, with one counterbalance arm clamped in position the other elevator is maybe 1/16" high or low. I guess something mustve moved slightly during drilling etc. It is as good as it will be and we will see how it flies! (one day, maybe).

Time to make it look like an aeroplane (mounting onto the aft fuse)

I have been looking forward to this step for a while. I lifted the aft fuse assembly onto the "saw horses" i have, and used a ratched strap to hold it gently down in case it tipped.

The HS was when placed into position and the front was bolted in place. The aft was clecod in place. To drill the 4 remaining holes, i needed to get creative. I wanted to drill the lower ones first and to do this, ended up using a right angle drill to drill to 3/16", then finally a 1/4" reamer on a very long extension. Bolts were installed as i went along.

The top holes were initiall drilled with #12, then upsized using the 1/4" reamer.

Once this was done, i installed the VS onto the assembly. The VS forward mounting bracket was installed and bolts torqued to 43 in/lbs (15 in/lbs running plus 28 in/lbs torque for MS21042-3 nuts).

Rudder installation (test fit)

Before installing the rudder, i wanted to check all the brackets. I first checked that all the brackets were 90 degrees to the spar with a square, with spacers underneath it to clear the rivets. I then placed a bit of builders string through the end of a pen and tied a knot to self-centre the string in the top hole. Pulling downward on it, and placing the string in the middle of the lower hole, i was able to check all the brackets were aligned.

Top - showing the pen end.

Middle - pretty close to bang on.

Bottom.

Happy with this, i did the same thing to the rudder itself. As a result of this, i wound the lower eye-bolt in by half a turn, and the centre one out by half a turn. Later on, i checked the counterbalance arm gap was parrallel at the top, and it was perfect 11/64 all the way along.

Top (showing the pen end).

Middle..

End - another pen end was used to ensure this was centre.

The rudder was then installed and had almost zero binding that i could detect. This will be re-checked at the final install - and at that time i will tighten the jam nuts. This task has been added to the deferred list, so it is not forgotten.

The rudder was able to achieve the following deflections - and no offset tabs or filing of the rudder stops was needed:

RIGHT: 34 Degrees

LEFT: 37 Degrees

Elevator Instalaltion (test fit)

The elevators were then installed using all hardware, and all bolts tightened and i was able to check the distance from the rudder as per the plans. These should be approximately 0.75" (close enough).

I was then able to check the elevator deflections as a whole unit for the first time. In this case, the elevator horns were hitting their stops in the aft fuse - i will leave these as they are, and file them at a later date with final installation of the empenange.