Expensive Mistakes!

[Don Jones]

Curious what expensive mistakes others have made during construction of the airframe? For me it was my most recent edge distance mistake while drilling the engine mount brackets to the longerons which required new longerons as well as the mount brackets. The parts themselves were not that expensive, but the freight was absolutely rediculous.

I can tell you that the second time you bend the longerons it goes a lot faster, just tastes really bad going down.

 

[Vlad]

The plane is not done yet could be more expensive mistakes. So far it was those stamped aluminum angles we use by flap brackets forgot the part #. I reordered the angles because I cut them three times and they were still short.

Now I am at electrical stage and moving very sloooow trying to learn as much as possible before connecting something. That's totally different measure of expensiveness .

 

[the_other_dougreeves]

Now I am at electrical stage and moving very sloooow trying to learn as much as possible before connecting something. That's totally different measure of expensiveness .

Yes, hook it up wrong and all the expensive magic smoke leaks out.

TODR

 

[AltonD]

I cracked my Canopy. $1050 canopy, $150 shipping.

 

[Don Jones]

Thanks

I cracked my Canopy. $1050 canopy, $150 shipping.

Thanks, now I don't feel so bad. Ouch that one had to really hurt!

 

[flion]

Screwed up a HS spar on the -10. About $60 for the part, over $200 for shipping. I had to redo the HS skins thanks to a windy day and the parts were about $80 but the shipping was under $40. Go figure. No truly expensive mistakes on the -6A but I am being much pickier on the -10.

 

[ignacio]

dinged up the rear spar on my -4 while tightening the straps on the skins. i over did it and the wood block used (per plans) dug into the spar. i think i spent 35 for the spar and 150 for shipping. i guess many of the parts we destroy can still be used but at night when your in bed tossing and turning.... well you get the point.

 

[Alternate]

I've got one that may give everyone a laugh. Today, I realized I had completely forgot to rivet the elevator Hinge Pins to my Horizontal Stabilizer of my RV-14.

Page 1, step 12. Just didn't do it because I was planning to prime the spars later.
View attachment PXL_20260711_010241985.jpg


So here's what a horizontal stabilizer looks like without the steel hinge brackets...
Vans builder support is going to get a call on Monday inquiring whether CherryMAX rivets could be used,
and if not, I think I'm simply going to start over, as there's no way that drilling 100+ rivets and re-placing them will be even close to what it is now, esp. if it's done by a guy whose forgetting major steps...

 

[Freemasm]

I’ve been in worse situations helping real A&Ps repair/rebuild stuff. Know a good welder? Welding a heavy foot onto a bar would get it done.

Find an experienced airframe man on you field. Reach out to experienced people here like @fixnflyguy . They’ve also seen tougher predicaments I’m sure. Just saying, don’t punt just yet.

 

[Alternate]

Know a good welder? Welding a heavy foot onto a bar would get it done.

Aren't the brackets steel? can they be welded to aluminum?

 

[wirejock]

I've got one that may give everyone a laugh. Today, I realized I had completely forgot to rivet the elevator Hinge Pins to my Horizontal Stabilizer of my RV-14.

Page 1, step 12. Just didn't do it because I was planning to prime the spars later.
View attachment 122858


So here's what a horizontal stabilizer looks like without the steel hinge brackets...
Vans builder support is going to get a call on Monday inquiring whether CherryMAX rivets could be used,
and if not, I think I'm simply going to start over, as there's no way that drilling 100+ rivets and re-placing them will be even close to what it is now, esp. if it's done by a guy whose forgetting major steps...

I removed the HS spar to do the SB. It's easy to drill the spar out. Maybe a couple hours at most.
Here's the quick way.
1. Punch the mandrel out of the blind rivets.
2. Drill the head with a #31 bit and stop set so it can't go deeper than the head.
3. Snap off the heads.
4. Punch every skin rivet in the spar with a auto punch. Get a good punch mark right in the center. Multiple hits if necessary.
5. Grab a #50 drill bit and drill every one. It's much smaller so even if it goes through, it's no problem.
6. Grab a #41 with a stop set so the bit can only go the depth of the head. Drill every one. Some will pop the head. Remove it from the bit and keep going.
7. Use the opposite end to snap off all the heads. If one is stubborn, leave it.
8. Go back and grab the shop head with a pair of side cutters and rotate. They will usually snap. If that doesn't work, carefully drill the stubborn heads just a tiny bit deeper. Snap those off.
9. Pull the spar and do what needs to be done.
10. Reassemble.

 

[rv6n6r]

This was years ago but... Brand new Garmin SL-30, decided I just had to try it out on the bench before installation. Hooked up the battery leads... backwards of course. The $400 flat fee to get it fixed seems like so little compared to what it would be now, but regardless it was painful.

 

[fixnflyguy]

It should be possible to make small aluminum plates with 5/32 nutplates on them and fish them through the lightening hole, then attach the hinge brackets with bolts/screws.

 

[Freemasm]

Aren't the brackets steel? can they be welded to aluminum?

Sorry. Wasn’t clear. I was talking about welding up a special bucking bar. The experienced airframe guys have seen/overcome worse.

There’s good advice above. I’ll add one more. If you’re going to consider the threaded fastener route, this would be a prime situation to utilize hi-loks; one sided fastener installed with zero tolerance or slight interference fit.

No reason to start over.