Tuesday, March 17, 2015

38-03 cowling pins

The RV-12 cowling is attached using an ingenious (or devious) implementation of a piano hinge.  Rather than using the hinge to permit rotation about the pin, the hinges are used as fasteners—think "giant zipper.”  They are often placed in curves, so no rotation is even possible, but by removing / inserting the pin it is possible to make a long and strong closure device.  This picture shows the 8 pins that hold the cowl pieces to the airframe and to each other.  The ones with “flags” on the ends were welded at the factory.  the others were bent and shaped by hand.  Almost all of them got trimmed a bit further as the process proceeded.  Also note that the ends are beveled and smoothed so they have the best chance of finding their way through each eyelet.



IMG 4111Locking pins and upper-to-lower cowl hinge

Because the hinges have to follow a curve, the edges of the eyelets are beveled to make it easier for the mating eyelets to fit in-between.  The Book calls for filing the half on the airframe (installed many months ago) and that’s what is pictured.  Later, I ended up filing the mating eyelets on the cowl as well.

IMG 4112

beveled hinge eyelets

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