As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE IN COCKPIT, 2 CABIN SIMULTANSOUSLY WHITE VISIBLE SMOKE APPEARED JUST AFTER ACFT SHUDDER ABOUT 6000 MGL SMOKE SM6460 SIMILAR TO BURNED PAPER. SMOKE DISAPPEARED AFTER ABOUT 30 SECONDS, EMERGENCY CLEARED RETURN. FOUND PACK 2 ACM DEFECTIVE. R & R ACM IAW AMM 21-52-21, PB 401. OPS CHECK OK. NO SMOKE NOTED. ACFT OK TO CONTINUE.