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Drilling skins to longerons

wirejock

wirejock

Well Known Member
I'm ready to start drilling the skins to longerons.
Question
Do I drill all the way to the forward end or stop at the F-704 center section bulkhead?
Forward of that, the longeron has some twist. I'm not clear if those holes should be drilled later.
 
I drilled my all at once.

One thing I did just because it seemed like a good idea at the time was alternate sides while drilling the holes. I'd drill five on one side, then five on the other working my way aft to forward. I looked back through my log and I must have done something right because my firewall fit perfectly and I didn't note any issues with any fitting of the other pieces. Do be careful of what hole you are drilling from the 704 forward. I know the front 5 or 6 are 1/8" holes and there might be a few others as well.
 
Thanks

Lemmingman said:
I drilled my all at once.

One thing I did just because it seemed like a good idea at the time was alternate sides while drilling the holes. I'd drill five on one side, then five on the other working my way aft to forward. I looked back through my log and I must have done something right because my firewall fit perfectly and I didn't note any issues with any fitting of the other pieces. Do be careful of what hole you are drilling from the 704 forward. I know the front 5 or 6 are 1/8" holes and there might be a few others as well.
Click to expand...

Thanks Gil.
I thought alternating sounded like a good plan.
 
I drilled all but the last few, the ones that go through the steel brackets. I did those a little later on, once I had checked once again to make sure everything was perfectly aligned.
 
Lemmingman said:
I drilled my all at once.
Do be careful of what hole you are drilling from the 704 forward. I know the front 5 or 6 are 1/8" holes and there might be a few others as well.
Click to expand...

Ah...its coming back to me. It was the dimples....keep an eye out for places you don't have to dimple.
 
Mine were done by the previous owner who had to do the longerons twice because he missed the rivet count at the firewall. There are a total of 14 (10 that go through the top engine mount + 4 that are aft of it).

He initially did a total of 10, including the 4 aft of the eng mount. Vans suggested it would probably be ok but at ~71% strength he opted to redo a month's worth of tedious work, including new top engine mounts.

Edited for clarity.
 
Last edited:
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