What was found
APU BLEED AIR: AFTER NORMAL STARTUP WHEN APU BLEED AIR SELECTED SMOKE FILLED THE CABIN AND COCKPIT (PER CREW, POST FLIGHT, NO PAX ON BOARD) // SIGNOFF// REPLACED APU WITH REPAIRED APU IAW CESSNA 680A AMM TASK-49-10-00, REFER TO 15,1 FOR LEAK AND OPS CHECKS, REMOVED P/N-3800785•1 S/N-P-814 INSTALLED P/N-380078S-1 S/N-P-763