What was found
AIRCRAFT WAS GROUNDED: CLIMBING OUT OF 15,000 FUEL IMBALANCE INDICATED. FUEL WAS FEEDING FROM CENTER TANK BUT LOSING 100 POUNDS A MINUTE OUT OF LEFT TANK. TOTAL FUEL QUANTITY WAS DECREASING FASTER THAN NORMAL. WAS ABLE TO STOP LOSS FROM RIGHT BY CROSS FEEDING FROM LEFT. WITH CONFIG IN CROSS FEED, STILL WAS DRAWING FROM CENTER TANK BUT UNABLE TO CORRECT IMBALANCE. IMBALANCE FELT IN FLIGHT CONTROLS. DECESION MADE TO RETURN TO BOS , EMERGENCY DECLARED AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE ACCOMP'D CROSS FEED FUNCTIONAL TEST REF AMM 28-22-00, FQIS DRY CAPACITY TEST REF AMM 28-41-00 AND FUEL IMBALANCE EXCEEDANCE CONDITIONAL TEST REF AMM 05-51-48 ALL WITH NO DEFECTS FOUND.