“‘But that’s how I received it.“
It goes without saying that scratch builders—those who turn self-sourced raw materials into aircraft parts—are the final arbiter of the fit and finish of the parts they install on their airplane. It would seem that unspoken responsibility would be obvious in the kitbuilt community as well, but it isn’t. Not from what I’ve seen. At least not to everyone. So I’m here to speak of it.
Kit manufacturers have to balance a part’s cost against its level of finish. That’s no excuse for a company to provide a wholly unusable part to a customer, but it is the reason factory-formed parts may need tweaking and factory-cut skins may need to be deburred. It’s the reason fiberglass parts aren’t ready to paint and install right out of the box and why pilot holes in thick, laser-cut parts may only be pinpricks. The more labor a manufacturer puts into a part, the more expensive that part becomes. The more advanced the capabilities of the manufacturing equipment that’s employed, the greater the cost becomes to manufacture that part. So decisions are made. Instead of a manufacturer deburring the edge of each part—a task that could double or more the cost of a small part—a kit manufacturer may choose to pass that labor, and the savings, to each builder. Deburring is within each builder’s skill set, while cutting a wing skin to precise dimensions may not be.
The final fit and finish of any airplane part, whether scratchbuilt or pulled from a kit’s box, is the responsibility of each builder. Workmanship standards should guide each builder to a level that meets best practices. There must be no stress risers. There must be no unpainted chromoly. Wing skins shouldn’t be deformed by forcing them over incompletely formed rib flanges. The edges of skins must let flesh pass over without drawing blood. Surface scratches that can be felt with a fingernail must be sanded out, and so on. Builders are the final step in ensuring the proper fit and finish of every part that is part of their airplane. “But that’s how I received it” is never an excuse for installing a part that falls short on workmanship.
