What was found
AFTER ENGINE START IT WAS NOTICED THAT THE INBOARD ROLL SPOILER HYDRAULIC CAUTION LIGHT REMAINED ILLUMINATED AND THEN THAT THE #1 HYDRAULIC QUANTITY WAS VISIBLE DROPPING. THE ENGINES WERE SHUTDOWN WHEN THE #1 HYDRAULIC QUANTITY REACHED APPROXIMATELY 10% AND THE CAUSE OF THE HYDRAULIC LEAK WAS INVESTIGATED. IT WAS FIRST FOUND THAT THE HYDRAULIC LEAK WAS IN THE LEFT FORWARD UPPER WHEEL WELL AREA. EVENTUALLY IT WAS DETERMINED THAT THE LEAK WAS IN THE #1 ENGINE DRIVEN PUMP CASE DRAIN HYDRAULIC TUBE. THE LEAK WAS CAUSED BY CHAFE DAMAGE TO THE TUBE DUE TO A CUSHION CLAMP THAT HAD DETERIORATED CUSHION RESULTING IN THE METAL OF THE CLAMP FRETTING ON THE TITANIUM TUBE AND CHAFFING A HOLE IN THE TUBE.