I normally leave my oil door open for cooling, one day the wind blew it closed and I missed that it was not latched on the pre-flight. Just as I was lifting off the door started flapping, I had enough runway left and landed so no harm was done. I saw a friends RV-7 that had a spring loaded door that opened when unlatched, that made me think of how to add that feature to the RV-12.
The pictures are self-explanatory. I wound the spring 4 coils out of .045 music wire. The spool is aluminum and I used a longer bolt to put it all together.
I added a 3/8″ x 1/2″ silicone tube glued with RTV to cushion the door from opening too far and chipping the paint.