It was always going to happen. Everyone says “you’ll screw up”, and of course everyone hopes they won’t. But you will, and as long as you get back on the horse it’s OK to screw up – we are inexperienced builders trying to make an aeroplane and it is not going to be a completely straightforward task!
J was back-riveting the stiffeners onto the elevator skins last week when he lost concentration and riveted past the back plate, causing the metal skin to buckle and the stiffener to warp. The back-riveting plate is behind the rivets to ensure the structure is held straight and to provide a flat surface onto which to set the rivet, and hitting the parts without that surface behind means they go quite badly out of shape. We’re going to have to replace them both.
We contacted Van’s when the incident happened – they were very responsive as usual, but said that whilst it may be possible to repair the cosmetic damage to the parts, there is no way of being sure they haven’t been structurally affected and thus it is advisable to replace everything, which is what we thought. If we just wanted a plane to look at, we probably wouldn’t bother, but we want to fly in this thing after all!
The actual cost of the parts is not particularly high (we think US$ 57 for all of the bits we need to replace), but it’s the 15+ hours of lost work that is disheartening. But there’s nothing we can do, and we’ll have to get used to bouncing back if we’re going to be succesful with this project.
I actually narrowly avoided a similar incident myself a couple of months ago – same process, same issue. I was lucky that I noticed and recoiled quickly enough to avoid hitting the metal properly and thus doing any damage. J was just a bit more decisive in his action, which is all it takes to be the difference between it being fine and having to re-do the entire assembly.
We have adjusted our processes to try and ensure it doesn’t happen again. We’d already been marking the end of the back-riveting plate with pen to show the point up to which it was safe to rivet. But inevitably you get into the rhythm when doing so many rivets at once and it’s easy to just keep going, which is what we both did. We’re now going to ensure we don’t even put rivets into the parts until we have moved the back-riveting plate behind to support them – this should make sure we don’t accidentally bash them and ruin any more parts (at least with this particular mistake!).
We’ve decided to park the elevators for now, largely due to the cost of shipping the parts – they are low cost bits to produce but getting them here from the US is costly. We are going to continue with the rudder and other elements of the empennage, and ship the replacement parts when the time comes to order our fuselage kit in a couple of months’ time. This will save a significant amount of money and it won’t cause a huge problem for our progress as there’s plenty to do that’s independent of the damaged elements.
The second bit we need to replace is the plate onto which the trim tab is riveted. Countersinking went a little bit wrong and has produced an oversized hole in the plate. This wouldn’t be a showstopper in every single case, but it’s a critical part and neither of us would feel comfortable leaving it if we know it’s not 100% up to scratch.
That’s all we have to confess for now…I’m sure there will be more, but for now onwards and upwards!