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Flap System Install (Sect 40)

TFeeney

Well Known Member
I've had a productive few weeks, so I guess I was due for a setback.

I followed the plans (40-3) and oriented the flap crank with the flap horn using the bellcrank jig provided. This is the left side being drilled, same as the plans...

oia.jpg


I've bolted the crank, tubes, and UHMW bushings into position with all the fiddly bits that go with it (spacers and washers etc). This picture is showing the motor in the flaps up/retracted position.

oid.jpg


Now looking at page 40-8, I find out that the flap horn is oriented 180 deg off from the plans. Unfortunately when I rotate the flap horn to the correct orientation, the bolts don't fit through the holes. Note that I only tried this on the right side horn. It is possible that the left side (which is shown in the first picture would still be able to rotate).

oiu.jpg


I've run the flap motor using a battery to perform the mental gymnastics in my head of how the wing connections will operate - so I think I understand the connections per the plans.

Has anyone else seen the same thing? I'm nearly positive I'll have to order a new torque tube for the right side (possible both), but am I missing something?

I did a search for my problem, but the only match I got was a question with no responses.
http://www.vansairforce.com/community/showthread.php?t=29674&highlight=flap+horn
 
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fyi, if you click on the images, and then come back to this page and refresh, you can see them. Strange as that might seem.

Also, look at page 40-8. I think you're right, your flap horns are 180 degrees off. Are you sure you haven't swapped the left and right tubes?
 
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Sorry for the photobucket links. I could see them on my side, so I thought all was well.

I've adjusted them. Never again....:mad:
 
I don't understand how you got from your first pic which shows the correct orientation to your bottom pic with the horn 180 deg out. Is it possible when you drilled the right side you didn't flip it (as it is the mirror of the left?) or that you inadvertently bolted the left (torque tube and/or horn) to the right side and vice versa?
 
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After disassembly of the fiddly bits, and reassembly on the bench, it turns out that the left side was correctly match drilled (as shown in the first picture). The holes were close enough that they still matched after rotating 180 degrees.

Apparently for the right side, I didn't understand the terms "mirror image". Those bolts will only insert when the flap horn is out of position. I'll be ordering new parts - unfortunately that means both the horn and torque tube ($85 + shipping). Expensive mistake.
 
Don't know if you have made the wing root aileron bellcranks yet, but for some reason, the plans show the left bellcrank on the right of the page and vice versa. Had me scratching my head for hours trying to work out why they wouldn't fit..............

Also, the elevator trim drive which fits in upside-down. I had the cranked link the wrong way round and spent literally days trying to work out why I couldn't get the right throws on the trim.
 
How close are the holes on the right side, close enough to ream, or are they way out of alignment? You might contact Van's to see if off setting and drilling two new holes would be acceptable.

Lynn
 
Knowing that I made the decision to replace the right side, I match drilled the horn to the torque tube in the correct orientation, which created a slightly oblong hole in the flap horn. I was then able to insert the bolts but I wasn't comfortable with this even though it was completely tight.

What I'm reading in your suggestion though is to rotate the horn 90 deg so that I could create new holes in virgin material (leaving the bad ones empty)?

oi8.jpg
 
Knowing that I made the decision to replace the right side, I match drilled the horn to the torque tube in the correct orientation, which created a slightly oblong hole in the flap horn. I was then able to insert the bolts but I wasn't comfortable with this even though it was completely tight.

What I'm reading in your suggestion though is to rotate the horn 90 deg so that I could create new holes in virgin material (leaving the bad ones empty)?

oi8.jpg

That was my thought. The holes would be in fresh material. If I remember correctly there aren't any clearance issues in that area, but I would run it by Van's just to make sure they are ok with the additional holes. Then the original holes would just be lightening holes. :0

Another thought might be going with a larger AN5 bolt depending on how far off the holes were when you flipped it around.
 
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Flap Horn Position Picture

Looks like all the links to photos in this post are dead.

I am thinking (dreading) I may have my flap horns drilled in the wrong position. Anyone have a photo of the flap horn position with the flap motor shaft fulled extended out...:confused:
 
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