As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT, SMOKE IN COCKPIT STARTED AND CONTINUED TO GET WORSE. "AIR RETURNED" AND SHUTDOWN ON TAXIWAY. SMOKE LESSENED WHEN THROTTLES WERE RETARTED TO ILDE AND COMPLETLY WENT AWAY AFTER SHUTDOWN. R & R HYD AIR PRESSURE REGULATOR IAW SMP. RAN ALL ENGINES IAW JRH TO 85 PERCENT N2, OPERATED PACKS, NO COCKPIT SMOKE NOTED. ALSO "A" SYS RESERVOIR HEAD PRESSURE NOW READS NORMAL. ACFT OK FOR SERVICE. PREMATURE REMOVAL/INSTALLATION.