As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH PACKS OPERATING AFTER ABOUT 15 MINUTES ON THE GROUND DURING PREFLIGHT, SMOKE FILLED THE COCKPIT. TURNED OFF LEFT PACK TO STOP SMOKE.FOUND BRAKE PRESSURE XMITR IN RT MLG WHEEL WELL LEAKING. REPLACED DAMAGED O-RING SEAL. LEAKAGE FROM XMTR LEAKING ON APU DUCT CAUSED SMOKE. OPS CK GOOD PER MM 29-33-1.