What was found
LEFT PROPELLER WAS FEATHERED IN-FLIGHT FOR TRAINING. UNABLE TO INITIALLY GET PROPELLER LEVER BACK FORWARD. FINALLY, WHEN LEVER BROKE LOOSE, A LOUD SNAP WAS HEARD. PROPELLER CAME OUT OF FEATHER. LANDING WAS UNEVENTFUL. UPON INVESTIGATION, FOUND BOTH PROP LEVERS COULD RIDE UP AND OVER FEATHER DETENT SPRING. FOUND THE INSTRUMENT PANEL CROSS-BRACE ASSEMBLY THE DETENT SPRING ATTACHES TO DEFORMED. THIS CONDITION ALLOWED THE SPRING POSITION TO CHANGE AND THE PROP LEVERS TO RIDE UP AND OVER THE SPRING AND JAM IN FEATHER. TO MAKE SURE THIS WILL NOT OCCUR, SPECIAL ATTENTION SHOULD BE GIVEN DURING ROUTINE INSPECTIONS.