What was found
ON TAKEOFF, AIRSPEED STAGNATED THEN BECAME ERRATIC. COMPLIED WITH QRH. RETURNED TO FIELD. R & R 3 PITOT TUBES IAW MM 34-11-02-2. PERFORMED A LOW RANGE LEAK TEST ON PITOT AND STATIC SYS. ALL TESTS NORMAL. NO LEAKS IN SYS OR LEAK DOWN. ALL PITOT LINES PURGED PRIOR TO PITOT TUBE CONNECTION AND NO OBSTRUCTIONS NOTED. AIRSPEED AND ALT CHECKED NORMAL ON AIR DATA SYS TEST. ACFT OK TO CONTINUE IAW AMM 34-16-00-5. ACFT REMAINS RVSM IAW GMM CHAPT 6.