What was found
(CAN) DURING STALL PRACTICE, VERY LITTLE AFT PRESSURE APPLIED TO CO-PILOT YOKE (AS PILOT WAS ALREADY APPLYING MOST OF THE PRESSURE), AND IT SNAPPED OFF. UPON RETURN FROM FLIGHT, TECH ON GROUND WAS ABLE TO SNAP BROKEN PIECE AGAIN WITH LITTLE FORCE. COPILOT CONTROL YOKE WAS MADE FROM PLASTIC. SL 62-44 SUPERSEDED SL 64-8 CALLS FOR A PULL TEST INSPECTION. THE CRITICAL AREA FOR ACFT IS THE BOTTOM LT CORNER. THE CONTROL WHEEL BROKE IN THE UPPER LT AND LOWER RIGHT CORNER. THE LITTLE BROKEN PIECE WAS BROKEN ON THE GROUND BY TECH WITH LITTLE FORCE. THE PILOT`S CONTROL WHEEL HAS ALREADY BEEN REPLACED WITH UPGRADED METAL TYPE CONTROL WHEEL. ACFT WAS STORED OUTSIDE FOR 8 YEARS. WE ARE BELIEVING SOME OF THE BRITTLENESS IS CAUSED BY SUN SOAKING. STEPS ARE BEING TAKEN TO REPLACE PART AT THIS TIME.