What was found
DURING COURSE OF ROUTINE INSPECTION, SUSPICIOUS 'BUBBLES' ON PUSH/PULL TUBE WERE POKED AT WITH SCRIBE AND WENT THROUGH TUBE. AFTER SCRAPING AWAY PAINT AND SCALE, FOUND LARGE OBLONG HOLE RUSTED THROUGH BOTTOM OF PUSH/PULL ROD NEAR INBOARD END OF RIGHT INBD FLAP PUSH/PULL ROD. HOLE APPROX .3750 INCH BY 2.25 INCHES. REPLACED WITH NEW PART. RECOMMEND A ONE-TIME ALERT SERVICE INFO LETTER ADDRESSING S550 AND 560 AIRCRAFT FOR ONE TIME INSPECTION AND POSSIBLE INTERNAL EXAMINATION OF TUBE.