What was found
DURING A ROUTINE RVSM INSPECTION, A SIGNIFICANT LEAK WAS IDENTIFIED IN THE CO-PILOT STATIC PRESSURE SYS. THE LEAK RESULTED IN A COMPLETE LOSS OF CO-PILOT STATIC PRESSURE SYS WHEN THE SYS MODE SELECTOR WAS IN THE NORMAL POSITION. DURING THE SUBSEQUENT INVESTIGATION, SOURCE OF LEAK WAS TRACED TO STATIC PRESSURE LINE, LOCATED BTWN FRAMES 28 AND 31. TUBE WAS FOUND TO BE FRACTURED ON THE INSIDE RADIUS OF AFT-MOST BEND. EXAMINATION OF THE FRACTURE INDICATES THAT MOST PROBABLE CAUSE OF FAILURE WAS MICROSCOPIC WRINKLING INTRODUCED DURING THE TUBE-FORMING MANUFACTURING PROCESS, WHICH PROPAGATED OVER TIME UNDER CYCLIC LOADING UNTIL A COMPLETE FRACTURE OCCURRED. WITH THE MODE SELECTOR IN THE NORMAL POSITION, THE CO-PILOT STATIC PRESSURE SYSTEM PROVIDES STATIC PRESSURE TO ADC 2, THE TRIPLE INDICATOR, AND BOTH THE PITCH AND ROLL ARTIFICIAL FEEL SYSTEMS(ARTHUR Q-UNIT). FAILURE OF THIS STATIC PRESSURE TUBE RESULTS IN THE LOSS OF A RELIABLE STATIC PRESSURE SOURCE TO THESE SYSTEMS, RENDERING THEM UNRELIABLE DURING FLIGHT OPERATIONS. TO PREVENT RECURRENCE, IT IS RECOMMENDED THAT A DETAILED INSPECTION OF ALL STATIC PRESSURE SYSTEM TUBING BE INCORPORATED INTO THE MAINTENANCE PROGRAM. INSPECTION SHOULD FOCUS ON HIGH-STRESS AREAS, PARTICULARLY TUBE BENDS AND FORMED RADII, TO IDENTIFY SIGNS OF FATIGUE, MANUFACTURING DEFECTS, OR CRACK INITIATION BEFORE FAILURE OCCURS.