34-04: Incorrect Flap Motor Length (the value of VAF Forums & the RV Community)

No sooner than 12 hours after i put up the post on the installation of the flap tubes & flap motor i got a conversation message on VAF from Tony (aka #stgiaro).

Tony points out, that the original stock motor (when extended) is 15 1/4" in length (or 10 1/4" retracted). I had not come across this figure before, and Tony was able to measure his original motor and indeed it is 10 1/4" long when retracted. This was backed up by an old post by Pat Hatch (from PH Aviation):

So since I had modified my flap motor mount brackets in accordance with the PG Aviation instructions, this moved the mount point 1.5" further away. 

This makes Tony's dimension totally correct - i need to install my rod end bearings so the motor (hole to hole) is 11 3/4" long when retracted (10 1/4" + 1 1/2" = 11 3/4"). This makes the extended dimension 16 3/4" (5" of throw). The dimension identified in the new Van's Instructions is not correct, as this relates to the use of the new, redesigned, Van's mounting brackets. 

Coincidentally, my mounting hardware arrived for the flap motor, so i was able to remove the rod end bearing and adjust it to the new dimension, then final install the flap motor using the new hardware. 

The top tape is the dimension of the old 'stock' motor. The middle tape is the dimensions of 11 3/4" retracted (showing how the new motor is 1.5" longer). As you can see, my rod end is clearly not screwed in enough.

Rod end adjusted to be 11 3/4" hole to hole length. This reminded me, in so many ways, of setting up a RC model for flight! 

11 3/4".

I was not able to use my trusty washer spanners here - could not get them to fit. So a bit of tape did the job.

Top hardware was AN5-15 bolt, with a AN5 thick and thin washer. 

The bottom hardware is as per plans - this uses a lock nut, as this bolt is not subject to rotation. The rod end bearing is clamped, and the bearing centre rotates in the bearing housing. 

Of course, as is tradition, i had to hook it up and give it a try!

34-02 -> 04: Flap Torque Tubes

I finally received my missing Flap Torque tube from Van's - it was missing when i cut the UHMW blocks and test fit the flap torque tubes, back in Chapter 32.  So i gave the newly arrived torque tube the same treatment - sanding down the edges of the powder coat transition, as well as a general sand all over the surface. I added some grease and did a test fit to the airframe - and the new torque arm slid in fine. 

Flap Crank Twist

So, onto page 34-02 for the drilling of the torque tubes to the flap crank. Page 34-02 asks you to clamp the flap crank to the table in order to complete the subsequent steps. To do this, i rolled back the carpet on my workbench and immediately noticed a problem - there was a slight twist in the flap crank. The holes for mounting the flap actuator, were not planar with the flap torque tubes. 

Here you can see, with the tube end parallel to the bench, the flap actuator end is not planar.

This is the opposite way - with pressure down on the front of the flap crank, the flap actuator end is parallel to the bench, but he flap tube end is not. 

It is off by a country mile. Expected i guess with a welded part.

This shows with the flap torque tube installed and parallel with the bench, the flap actuator end of the weldment is not parallel, and was floating above the table. 

The issue with this, is the only place i can clamp that weldment to my table is at the front. But by applying pressure it throws the torque tube end out of alignment - since the outer end of that tube needs to be flat and clamped to the bench (with the alignment template), i needed to add a shim under the forward end of one side of the flap crank. This allowed me to clamp it to the table, while keeping the torque tube end parallel to the bench. The misalignment at the flap actuator end will not be an issue, as the flap actuator has a CM4-4 rod end bearing to interface with the flap crank. 

A scrap was used as a shim.

With the shim in place, the flap torque tubes are parallel to the bench. 

Drilling the Torque Tubes

So with that sorted, I was able to clamp the flap crank to the table, slide on the aileron alignment jig (which turns out to be a multipurpose tool!), and set the required length of the tubes. I was then able to clamp down the outboard end of the rube, and match drill #30 the first hole. The plans ask you to match drill the upper, outboard hole in the flap crank, then match drill the hole opposite this, before removing the clamp. This was impossible, as the opposing hole was facing the work bench. So I just match drilled the other (inboard) hole on the top of the flap crank, before removing the clamp, flipping it over and match drilling the other holes #30. They were then drilled to #19, and reamed to 3/16" for an AN3 bolt. Everything was then removed and deburred. 

The multi-purpose aileron alignment jig!

Since my brain is made of metric cells, i marked the required distance (23 5/16") onto my tape. 

I used my screw on toggle clamp to hold the tube down for match drilling.

Priming the inside of the tubes

I primed the inside of the tubes using Norglass ShipShape, 2 part epoxy paint. I first dragged a rag soaked in Iso back and forth, then a scotchbrite pad, then another rag. One end of the tube was covered in masking tape (blocking it off). I poured in the paint and capped the open end with tape. Then sloshed the paint around and left the tube hanging on the edge of a drawer, draining the excess paint into a cup. 

Installation into the Fuselage

Finally, the torque tubes were generously slathered in grease and slid right in with no troubles. I was then able to install the called out hardware and torque the nuts.  

The insides of the tubes are nicely coated in paint.

I checked the rudder cable were above the flap torque arms on each side using a mirror.

This is why all my tools are on wheels - was not able to slide the right tube in place, as my power-tool bench was in the way. Luckily, i just moved it out of the way.

Pinning and checking the flap motor

EDIT: The dimensions for the flap motor shown in the Van's plans, are not correct if you modify the motor mounts in accordance with the PH Aviation Instructions. They are only correct if you use the new Van's flap motor mount brackets. The correct dimensions are outlined here.

The flap motor i am using is not stock, but is a unit i purchased from Van's which was offered as a replacement for the RV10 (as detailed here). Because of this, there is a bit of a lack of information on how to retrofit the unit into a RV-14. There are the PH Aviation Instructions (which i used to modify the flap brackets), and there are the RV10 Alternate Flap motor instructions. Unfortunately, the RV14 flap motor retrofit instructions (OP-65) have not been published as yet. However, on the forums people were reporting that their fuselage kits were arriving with the alternate flap motor, and the printed instructions showed how to install it! So luckily, i was able to glean some information from the forums to install the rod end bearing, and set it's length. I was also able to check the throw of the motor was correct (which it was). Once this was done, i wired on a CPC Series 1 connector, and test fit the motor into the aircraft using an AN5 and AN4 bolt - the actual hardware (correct length bolts) is on it's way. 

The printed RV14 Instructions shipping with the current fuselage kits has instructions for installing the CM4-4 rod end bearing, and the correct length for the unit. 

This hardware should be perfect. 

This hardware is not correct due to the custom made flap bracket modifications i made. I need a longer bolt, and no bushings.

The wiring colour matched the actual motor. There was also a black wire which was snipped off. 

The throw of the motor is spot on.

A free-hanging male (pins) CPC connector was installed on the motor (the tape is some female sockets pushed on for testing).

My wiring diagram was kept up to date and connector and wire gauge information updated.

Of course, i had to check that the thing worked:

32-07: Flap Motor Brackets - Modification

Page 32-07 has us trim the flap motor mounting brackets. Since i am going with an alternate flap motor, the stock brackets will not place the motor mount holes in the correct locations (the alternate flap motor is 1.5" longer).  

Van's announced in previous months that they would be releasing some alternate flap mount parts which matches up with the new style of flap motor (and to look out for OP-65). Since Van's is having some issues (fingers crossed, touch wood), i decided to go ahead and modify my flap motor mounting brackets to fit the new flap motor. I may or may not proceed with riveting these into the airframe - will wait until i really have to install them. 

The modifications are detailed in the PH Aviation Flap Motor Instructions, and i followed these. 

The plans call for 1" x 1" x .063" angle - however i did not have any of this in stock. Not sure why, but i had 6' of 1" x 1" x 0.125" angle (twice as thick). Since the flap motor mounts between the brackets, the thickness will not affect the geometry - but i will need a longer bolt. 

I started by marking our and drilling 4 x #40 holes into one of the two flap mounting brackets, where the rivets will go to attach the angles. 

These were match drilled from one bracket to the other using a flat backrivet plate to make sure they are in exactly the same spots.

The plans call for AD4 rivets, so i made sure i had 1/4" of edge distance from the holes on one side...

..and on the other, that the tails of the rivets would clear the vertical part of the angles.

These holes were then match drilled into one of the angles..

..and i marked where the flap motor mount was supposed to be according to the instructions. 

I then checked this spot against the original hole - it needed to be 1.5" shorter, and it came out perfect. I then drilled a #40 hole at this location.

Then all the holes were transferred to the other angle.

Initial trim of the mounting brackets.

The brackets were then clecod together and placed into the airframe to measure the distance between the new bracket mounting faces.

These were installed with no shims, to measure how thick the shims needed to be.

The brackets, with no shims, are 0.8020 apart. 

This is the EXACT same width as the mounting boss on the flap motor. But i need to mount it with washers, to act as bearing surfaces when it rotates...

So i measured some thin and thick AD5 washers, and found the thin ones were 0.032" thick.. 

..and the thick ones were 0.063" thick. 

I happened to have some flap bracket parts left over which were were close to the same thickness as one thick AD5 washer. So i used these to make 2 shims to go between the flap angles and the flap mounting brackets.

On the -14 you get extra flap brackets - as they ship the same parts package as the -10. 

Test fit with the modified brackets, angles and shims

I checked the clearance to make sure the flap motor had enough travel to extend the flaps. 

As i suspected, the called out AD5-13 bolt is too short - as i have added 0.125" of thickness to this stackup. 

The hole measures as 1+3/16"

So i will need an AD5-15 bolt. 

All these parts have been set aside for priming, and i will rivet these flap brackets together when i get to the next session. I will not install them in the aeroplane until the last minute - in case Van's releases a better solution. 

Edit: With the Chapter 11 going on at Van's, i assumed that it would be a loooooong wait for OP-65 to be released, so i went ahead and installed these into the aircraft

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