Date: 201310
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: IMC
Weather elements / visibility: Thunderstorm
Light: Daylight
Aircraft: B757 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Turbine Engine
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Human factors: Troubleshooting; Workload; Confusion; Distraction
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; General Maintenance Action
Contributing factors: Aircraft; Weather
Primary problem: Ambiguous

Narrative: En route we had been briefed by ATC about thunderstorms along our route of flight. There was no practical way to avoid the area of weather so we continued on with the plan of deviating as necessary. Both the Captain and I had our radar displays selected. I noticed an area of widespread green returns about 80 miles ahead and mentioned it to the Captain. He said nothing at the time. Once we came closer to the area nothing stronger than a green return was seen; and there was no real way to go to avoid it. Aircraft ahead were reporting moderate turbulence higher so we elected to stay at FL320 where the worst turbulence encountered was light and only occasionally so.The flight attendants had previously been told to discontinue their service and take their seats; though I could hear galley doors closing and general activity in the galley. Halfway through the depicted radar returns we could begin to see a new area being painted that was orange in color in some areas; with again; no way to go around it. The Captain slowed the aircraft; and quickly got on the PA system to instruct the flight attendants to take their seats immediately. Turbulence increased from occasional light to constant light to occasional moderate. The engine and wing anti-ice systems were already ON. The aircraft soon became caught in up and downdrafts that took us +/-200 FT from our assigned altitude; though it was gentle and imperceptible. The airspeed fluctuated and the Captain assisted the autothrottles in maintaining airspeed. Soon we could see what was likely St. Elmo's Fire and quite possibly lightning near the aircraft. Precipitation in the form of rain pelted the windows. The lightning intensity increased; and the aircraft once rolled 20 degrees to the right; but was quickly righted. I scanned the EICAS engine instruments for any anomalies and right then a loud BANG was heard once; and then right engine lost power momentarily; perhaps .05 EPR; 5-10% N1; and about 30-50 degrees of EGT. The power loss was maybe a second in duration; though it took about five seconds for the engine to regain commanded thrust. At roughly the same time a very strong acrid burning electrical smell pervaded the cockpit. No smoke. The EICAS never showed any messages; and when pressed; the systems function buttons near the jump seat panel did not show anything abnormal. The cabin crew chimed us to say they heard the loud bang and the acrid smell was throughout the cabin; as well. The scent lasted for probably two minutes before dissipating on its own. No other problems were encountered; the rest of the weather was visually maneuvered around; and we continued onward toward our filed destination. On descent at approximately FL200 and again at 7;000 FT the scent came back; though not nearly as strong. It again came back after landing while taxiing to the gate.




Synopsis: A B757 at FL320 in icing conditions and turbulence near a thunderstorm experienced a loud bang and momentary power loss along with an acrid electrical odor which dissipated but then recurred several times during descent.