Saturday, October 13, 2012

Assembling Flaperon Hinge Bearings .. Or Not

Yesterday was a mixed bag at DOG Aviation spent replacing air hose fittings, procuring a drill press vice plus the hardware to mount it and work continued on the RV-12 preparing to assemble the two flaperon hinge bearings.

As for the air hose fittings, back in March a 360 degree air hose swivel with an airflow adjustment valve was purchased … which although handy, leaked air with any side loads and after a summer of use, it just began leaking air continually. An attempt was made to replace the O rings but after taking it apart and seeing how poorly it was machined, decided to just throw it into the trash.

I liked the multi-turn adjustable valve with a full off … it made changing pneumatic squeezer sets and drill bits much safer because the airflow to the tools could easily be turned off.  So set out to find a replacement made by another manufacturer. All 360 degree hose swivels with regulators may look the same, but they are not ...  some don’t turn off the air flow completely, some only have a 1/4 turn air adjustment which makes low airflow adjustments very difficult when compared to a multi-turn valve.

The DOG Aviation procurement department has finally found a seemingly higher quality replacement for only $12 … the Nova 360 degree swivel air regulator from Pan American. The swivels appear to be machined well, don’t leak from side loads (yet), move smoothly and are cheaper than the old one that wore out.
                             The Nova 360 degree swivel air regulator from Pan American Tools … only $12.
                             If you have air tools, you need this item at the end of your air hose.

Work began on assembling the RV-12’s flaperon hinge brackets but quickly hit a road block because the components were warped from the stamping process at the factory. Owning a press would be quite helpful but the 10 minute job ended up taking a couple of hours of hand trial and error before I was remotely happy with the fit and squareness of all the flaperon bearing components. Once the bracket components were squared and flat there were two rivet holes adjacent to the bearing that require countersinking on BOTH sides of the bearing brackets. Once again a flush shop head is required to be formed in a countersink so the result is a smooth surface on both sides of the rivets.
                                       Preparing to make100 degree countersinks in two of the flaperon bearing
                                       bracket rivet holes adjacent to the bearing using the drill press.
           Flaperon hinge bearing components all square, flat and countersunk … ready for assembly and riveting.

Being frustrated that such a seemingly easy task took so long, decided it best to leave the riveting for another build session.