What was found
PDIS 920 34-16 3550 19MAR22 CDG OPEN U ON CLIMB THRU APPROXIMATELY FL280, THE FIRST OFFICER S SPEED TAPE READ, NO SPD AND THE ALTIMETER JUMPED SEVERAL HUNDRED FEET FOR APPROXIMATELY 1 SECOND BEFORE RETURNING TO NORMAL. RH AND LH AIR DATA COMPUTERS BITE TESTED IAW AMM FIM 34-12 FT 813, ALSO FPDS TEST C/W IAW AMM 34-22-00-5-99, ALL TESTS PASSED, PITOT TUBES INSPECTED FOR CONTAMINATION WITH NIL FINDINGS IAW AMM 34-11-01-6-0, NO RELATIVE HISTORY FOUND IN 90 DAYS, A/C OK FOR SERVICE. MDIS 920 34-16 3554 19MAR22 22:24 CDG FACT REF WRI 34-16/3550, NEED TO REPLACE PRECAUTIONNARY R/H ADC COMPUTER. R/I 19MAR22 22:27 CDG REASON CODE : PREMATURE REMOVAL/INSTALLATION OFF MPN: 4040800-912 POS: 2 SRL: 95034295 TAG NBR: 6489E5 ON MPN: 4040800-912 CPN: 3414864 SRL: 89122022 TAG NBR: 2H4641