I was flying my freshly built Yak-54 foamie down the park, miles (ok, several hundred metres) from anything solid and upright. Not long into the flying, during a gentle left turn the ailerons stopped working - not good with about 50% deflection and full-span ailerons! Tried recovery with opposite rudder and a lot of elevator but no dice. The damned thing went into an inverted spin and didn't recover. Lucky for me, some kind farmer had left a line of star pickets with barbed wire to arrest the descent!!! Grrr. Anyone got some glue???