While going through my AD's from compliance, I have been back- checking to see why each AD marked N/A was so marked. I came upon AD 47-20-06 ERCO which on the surface looks like a needed reinforcement to the lower aileron skin. After reviewing Ercoupe Service Bulletin No. 20, I see that this reinforcement is at the place where the Aileron Balance Assembly (part no. 415-16009) is attached.
Looking at the drawing in SB #20, it looks like this little device hangs off the bottom of the aileron with a weight attached to an arm. I suspect that as this arm bounces up and down it flexes the aileron skin to where it is attached, hence the requirement for reinforcement. So here is my dilemma. I can't remember seeing any such device attached to the bottom of my wings. I checked the parts catalog, and sure enough there it is. Then I went and checked my Coupe: no such device. I even checked another Coupe here at the airport (honest Linda, I didn't touch the Sky Sprite I just looked), and it didn't have aileron balance assembly either. Here is my hypothesis: there was a time that the aileron balance assembly seemed like a good thing to have. That time has passed and therefore the needed reinforcement has passed. Who can tell me more about this? Thank you. Frank Nelson N51DV 415C TOA/California
