What happened
During the climb out phase of the flight, the flight crew encountered acrid smoke in the cockpit. This was immediately followed by the illumination of the main deck cargo fire light and an accompanying audio warning bell. In response to these indications, the crew performed emergency procedures and declared an emergency, returning to the departure airport for a normal landing.
During the downwind leg of the approach, the main deck cargo fire light extinguished. However, while on final approach, the mid 2 loops A and B illuminated. Following the landing, the crew attempted to evacuate the aircraft using the 1R emergency slide, but the slide failed to inflate. The first officer reported that although the door could be opened, several attempts to manually inflate the slide were unsuccessful.
The investigation
Post-incident examination of the equipment revealed that the inflation bottle for the slides was fully pressurized. Two maintenance personnel observed that a transport-locking pin was located with the slide when it was removed from the aircraft.
Upon disassembly and inspection at the manufacturer's facility, no discrepancies were found that would have prevented the slide from inflating. However, investigators found damage to the slide's girt bar near the manual inflation handle. This damage was consistent with the transport-locking pin being installed in the inflation bottle's regulator during the deployment attempt. Additionally, the source of the cockpit smoke was identified as oil or other fluid contamination within the air-conditioning packs.
Findings
- The crew experienced an emergency due to smoke in the cockpit caused by fluid contamination in the air-conditioning packs.
- The failure of the 1R emergency slide to inflate was attributed to the presence of a transport-locking pin in the inflation bottle's regulator at the time of use.