An air carrier crew reported that when the wing and engine anti-ice were turned ON while climbing IMC; electrical fumes were detected throughout the aircraft; so an emergency was declared and the flight diverted to a nearby airport.
Synopsis
An air carrier crew reported that when the wing and engine anti-ice were turned ON while climbing IMC; electrical fumes were detected throughout the aircraft; so an emergency was declared and the flight diverted to a nearby airport.
Narrative
The aircraft came with a write-up; 'Electrical fumes reported in cabin when engine/airfoil ice was turned on.' Maintenance could not duplicate and signed off the logbook entry. Flight was delayed due to a different maintenance problem. The problem was a hydraulic leak discovered by the ramp crew just prior to departure from the gate. That problem was fixed and flight departed approximately 90 minutes late. The rest of the flight was uneventful. During climb from FL320 to FL360 [in our next flight]; we were in IMC and light to moderate rain showers. We encountered icing conditions passing approximately FL330. Shortly after the engine and wing anti-ice was turned on; a strong electrical burning odor became apparent in the cabin and the cockpit. The flight attendants called the cockpit to report the fumes and we acknowledged same. The anti-ice was turned off and the burning smell began to dissipate. At this point we elected to level the aircraft at FL330. Within seconds of leveling the aircraft; both engines began to compressor stall. We immediately disconnected the auto-throttles and reduced power. The engine heat and ignition was turned back on which stopped the compressor stall. At this point we attempted to contact ATC for a lower altitude; but the radio antennae had apparently picked up so much ice in a very short time that we could not hear ATC on either radio; static only. We were also dodging thunderstorms at this point. '7700' was selected on the transponder and we continued a descent to a lower; warmer altitude so that the engine anti-ice could be turned off. Upon reaching FL180 we were able to turn engine anti-ice off again and the electrical burning odor subsided. Once the communications were restored; we confirmed the emergency declaration and diverted. The visual approach and landing were uneventful. After clearing the runway; the aircraft was inspected by ARFF; [who] reported no apparent damage to the aircraft. The subsequent taxi in to the gate was uneventful.
Second reporter narrative
The aircraft came in with a write-up; 'Electrical fumes reported in cabin after engine and wing anti-ice turned on; during the last few minutes of the flight.' Maintenance could not duplicate and signed off the logbook entry. Our first flight with this aircraft was uneventful. Next flight was a return flight. During climb from FL320 to FL360; [we] encountered icing conditions passing approximately FL330. Shortly after the engine and wing anti-ice were turned on; a strong electrical burning odor became apparent in the cabin and the cockpit. The flight attendants called the cockpit to report the fumes and we acknowledged same. The anti-ice systems were turned off and the burning smell began to dissipate. At this point we stopped the climb at approximately FL330. Shortly after leveling the aircraft; we noticed compressor stalls on one or both engines. The auto-throttle was disconnected and the engine heat was turned back on. The compressor stall stopped. Due to icing conditions; we were unable to communicate with ATC to obtain clearance to a lower altitude; static only on both radios. Captain's emergency authority was exercised and 7700 was selected on the transponder. We broadcast in the blind on Center and Guard frequency that we were descending. We began an emergency descent to a lower altitude. Upon reaching approximately FL190 we were able to turn engine anti-ice off. Once the communications were restored; we confirmed the emergency declaration with ATC and diverted to a nearby airport. ATC confirmed that they heard our blind radio calls. A visual approach and landing were uneventful. The aircraft was taken out of service.
NASA callback
The reporter did not know what the source of the smoke was but if he had to guess it would be from the wing anti-ice hot air heating wires somewhere.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.