Piper PA-23 Drain Valve STC

Installation
The fuel cell is removed and the bottom inboard aft attach point is removed from the fuel cell. Then a rubber drain nipple is vulcanized into the same location on the fuel cell. The wing is then modified by drilling out the four rivets that hold the corresponding attach bracket to the lower wing skin in a diagonal pattern. The bracket is removed and discarded. Next the center of the hole where the valve will pass through the skin is located by marking crossing lines from one rivet hole to the other. The valve hole and a small hole adjacent to it are drilled. A rivnut and fillister screw are installed in the small hole. The fuel cell with the valve hose clamped in place is inserted into the cavity. The valve drops through the valve hole and is secured with a rubber spacer, stainless steel washer, drilled check nut and safety wired to the fillister head screw.