Incident Overview
On June 16, 2010, at 1330 UTC, Delta Air Lines flight 139, a Boeing 767-332ER registered as N196DN, experienced a cockpit fire during preflight preparations at Eleftherios Venizelos International Airport (LGAV) in Athens, Greece. The fire occurred prior to passenger boarding, and there were no injuries to the three flight crew members and an unknown number of cleaning crew personnel on board the aircraft.
Sequence of Events
During the preflight process, ground maintenance personnel performed a "push to test" on the right sidewall accessory panel (P61). After an undetermined period of time, the first officer, who was continuing with preflight procedures, smelled smoke and then observed a flame coming from the right sidewall accessory panel. He extinguished the fire using a halon fire extinguisher.
Investigation
The investigation was delegated to the National Transportation Safety Board (NTSB) by the Hellenic Air Accident Investigation and Aviation Safety Board. The panels involved in the fire—the squib test panel and the miscellaneous test panel—were removed and sent to Boeing's Engineering Quality Analysis (EQA) laboratory in Seattle, Washington. On September 16, 2010, the panels were examined under the direction of the NTSB.
Examination Findings
The existing condition of the panels submitted for examination was documented, tests were conducted where possible, and chemical analyses were performed on some samples. The damage on the squib test panel was most severe around the light in position L3.
During tests of the L3 light, the resistance between terminals 2 and 3 varied from 0.6 ohms to 4.6 ohms. Based on the damage to L3, it could not be determined if a short initiated as a result of physical damage, a conductive path of contaminants, a workmanship error that may have been created when L3 was removed and replaced, or a manufacturing defect with the lamp itself.
While only 14 ohms were measured between terminals 1 and 2 of L3, it is believed that this short occurred after the press-to-test was performed per the preflight process and as a result of the heat generated from the short between terminals 2 and 3. If this value actually existed during the preflight, the current would have been significant enough to discharge the fire bottles. However, the fire bottles were not discharged during the incident.
Switch S5 on the miscellaneous test panel showed evidence of heat damage on the bottom of the switch. Switch S5 on the miscellaneous test panel is almost directly above light L3 on the squib test panel.