What was found
AT 90 KTS, NR 4 ENGINE COMPRESSOR STALLED, ABORTED TAKEOFF. FOUND LOOSE PNEUMATIC LINE AT INTERSTAGE BLEED VALVE. TIGHTENED LINE AND OPS CHECKED AT ALL POWER SETTINGS. FLAGGED BLEED VALVE SEVERAL TIMES, NO DEFECTS NOTED. ENGINE WAS RUN AT TAKEOFF POWER WITH SEVERAL THROTTLE BURSTS, NO PROBLEMS.