What was found
IN FLIGHT THR NR 1 'A' SYSTEM HYDRAULIC PRESSURE FLUCTUATED AND THE LOW PRESSURE LIGHT ILLUMINATED INTERMITTENTLY. 'A' SYSTEM HYDRAULIC QUANTITY AND PRESSURE WENT TO ZERO. COMPLETED LOSS OF HYDRAULIC CHECK LIST NORMAL LANDING COMPLETED AT IND. FOUND O-RING LEAKING AT ELEVATOR FEEL COMPUTER FILTER ASSY. REMOVED AND REPLACED O-RING. LEAK AND ELEVATOR OPS CHECKS NORMAL PER MM 27-30-91. (M)