Dan Siebold:
My mouse is in for annual and I need a door hinge. I have the piano hinge rather than the two surface hinges. Found the NAS40 hinge supplier in CA, Genuine Aircraft Hardware. Does anyone know the exact specs (width, length, etc) for the hinge? Looked through the archives and BAC stuff and couldn’t find it.
Editor:
The NAS40 dash four (3/4″ from pin centerline to edge of flange) will work. It is close to three rivet diameters from the centerline of the rivet row, to the edge of a -4, 3/4″ wide flange. The replacement rolled hinge being sold by RAPID is 3/4″ flange hinge. One half of the replacement is 19″ long, and the other is 19.25″ long.
Since it is sold by the foot, you’ll need a two-foot length. Note that the NAS40 is sold in halves. If you need both sides of the hinge, you’ll need two 24″ lengths. If you do a rough measurement of your doors for insurance, you can estimate the actual needed length pretty easily (the length of the hinge pin). Don’t forget to order new hinge pin material. The NAS hinge pin material is no longer available; you can legally substitute the MS-type pin. It is an approved substitution. Its only drawback is that it is one-thousandth of an inch smaller in diameter, which actually makes it easier to install without adding much play. Unless you have a broken leaf on both sides (or a seriously worn hinge bore), you only need to replace the bad side and the hinge pin.
As I have posted before, taxiing with an open door, and especially doing start-up and shut-down with the door open, is what breaks the piano hinge. If you don’t have powered cabin ventilation (or a Kool-Scoop), and must therefore use an open door during hot weather, at least keep it closed during start-up and shut-down.