What was found
ON DEPARTURE ROLL AIRSPEED DESCREPENCY OF 40 KTS LOG PAGE CLEARED IN REFERNCE TO LOG PAGE 3978826. SEE FORMENTIONED LOG PAGE FOR UPDATED DETAILS. DURING INSPECTION IT WAS NOTED THAT F/O AIRSPEED INDICATOR, TRACKED UP AND DOWN ON MECHANICAL DIGITS, DURING STATIONARY INDICATION AND FAILED TEST, ALSO TRACKED UP AND DOWN USING ALT SYSTEM. ROTABLE PARTS CHANGE WAS INDICATED - TT # 1652315 SN OFF 9591 INDICATOR, MACH OFF 75-3111-9-0001 9591 ON 75-3111-9-0001 0008 F/O AIRSPEED INDICATOR R/R IAW AMM 34-13-02-404-003 WHICH INCLUDED OPERATIONAL TEDT OF AIR DATA COMPUTING SYSTEM REF AMM 34-12-00-715-001, STSTEM OP CHECK SATIS. AIRCRAFT SYSTEM SERVICIBLE FOR FURTHER FLIGHT.