HI
I THINK THE FORCES ON THE CONTROL SURFACE MAY EXCEED THE OUTPUT FORCE OF THE SERVO (IN OUNCES ) THAT IN ADDITION TO SERVO WEAR ( MOTOR,GEARS,ETC ) AND SLOP THAT DEVELOPES IN THE LINKAGES-( PROPER MAINTENANCE SHOULD BE PREVENTING AND IDENTIFING THIS CONDITION ) ALL ADD TO THE FLUTTER PROBLEM DEVELOPING- QUICK IDENTIFICATION OF THE SOUND OF FLUTTERING AND PULLING BACK THE TROTTLE ( QUICKLY ) TO LAND QUICKLY MIGHT BE YOUR ONLY SAVIOR-THE FLUTTER IF LEFT TO CONTINUE WILL DESTROY YOUR SERVO GEARS AND TAKE YOUR CONTROL SURFACE OUT !!-LOSS OF THE PLANE WILL FOLLOW-,TWO SERVOS ON 40 AND UP AIRFRAMES IS RECOMENDED ESPECIALLY IF YOU OVER POWER YOUR AIR FRAMES AS I CHOOSE TO DO ALWAYS (HOT ROD RC ) I MUST SAY AFTER FLYING FOR OVER 20 YEARS A LOTIN SOME WAY THE PLANE USUALLY GIVES YOU A SIGN THAT A PROBLEM WILL FOLLOW-LEARNING TO READ THAT SIGN WILL OFTEN PREVENT THE LOSS OF THE PLANE -( REQUIRING YOU TO THINK AND REACT FAST ) TO FLY ANOTHER DAY ENJOY BEST REGARDS TONY