Vol. 4 May 2006
Velocity's Quarterly Newsletter

Mechanic's Corner

Aileron Problems and Fixes

Sam Andersen

During a recent test-flight I was taking a Velocity through a series of maneuvers and unusual attitudes at various airspeeds.  I took note of something that I believe will be of worth to those of you who are building your airplane and those who have already completed your kit. 

Let me describe to you what I have found.  I noticed that when I would bank the airplane in a medium banked turn in one direction and then abruptly applied opposite aileron, at some point - usually after passing through wings level and into the opposite direction - a shake would occur on the wing with the aileron in the up position.  In other words, the wing that had the leading edge of the aileron into the relative wind would begin to shake.  In some cases and variations of airspeed it would be severe enough to cause the winglet to shake nearly to the point that it seemed as though it were flutter. 

Flutter was not the problem.  After landing to inspect what the problem could be we determined it was not rudder flutter.  The shake began on the wing and not the winglet.  It was then carried into the winglet as it intensified.  I took this opportunity to tuft the aircraft and duplicate the results.  The tufts showed no disturbance in air passing over the wing, even when the shaking was most severe.

I landed again and inspected the aircraft.  Upon further inspection I realized that the leading edge of the aileron was sharp.  It had not been rounded off or sanded smooth.  After consulting with Scott Swing we determined that this could be one of the causes. 

I rounded off the leading edge and went for another flight test.  This time the wing did not shudder or shake as it had before.  Though there was still a remnant of the shake.  Having drastically improved the situation by rounding off the leading edge of the aileron I determined to round it off even more.  After doing this I performed another flight test and operation of the aircraft was normal through all attitudes and airspeeds.

After inspecting a couple other aircraft that were flying I saw that they had the same sharp edge on the aileron.  Subsequently those aircraft have sanded the leading edges of their ailerons to prevent the issue. 

Take the time to inspect your ailerons, even if you have not experienced any shake as I have described.  It is important to have a safe aircraft in all configurations of flight, and to plan for the unexpected.