Flight Crew Air Transport Pilot (ATP)
Troubleshooting
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Aircraft Equipment Problem Dissipated; General Evacuated; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
During preflight a single pop sound was noted along with a noticeable change in the sound of airflow in the flight deck. Very shortly afterward smoke was observed entering the flight deck from the air vents. The packs were selected off and after a short period of time smoke was still observed entering the flight deck. The recirculation fans were then selected off.The odor of the smoke did not appear to be an acrid electrical smell. The smoke did not diminish and the packs were reselected on. When the packs were reselected on; the level of smoke intensified. The packs were immediately selected off and all personnel were advised to immediately exit the airplane. Crash Fire Resource (CFR) was notified and the aircraft was completely depowered.CFR arrived at the aircraft and began the process of finding the source of smoke in the cabin. The onboard mechanics sourced steps and opened the APU access doors as the APU was suspected to be the source of the smoke. When the APU access doors were opened; large volumes of smoke poured out of the APU compartment. CFR examined the APU compartment for evidence of fire and no fire was noted. The aircraft cabin doors were opened to vent the smoke in the cabin. CFR released the plane back to the crew.
Captain reported malfunction of the APU at the gate resulting in smoke throughout the aircraft. Crash Fire Rescue (CFR) was called while personnel left the aircraft. APU was shut down.