Narrative:

At FL200 number 2 engine rolled back suddenly. All fuel pumps had been on since preflight. A lot of yaw and bank. Disconnected auto flight and throttles. Started descent. Checked engine rotating and turned on continuous relight. Left ECAM disappeared or diminished. Was it at idle or sub idle? I don't know. Lights but no horn. Checked that the engine responded to throttle movement then left it at idle and flew with auto throttles disconnected. Only used the engine for thrust reverse on landing and to taxi.did the long checklist. Contacted ATC. They asked if we wanted the trucks ready or rolled. While I was thinking they made the decision. I would have rolled the trucks also. I think they could have gotten in place sooner as I had a lot of localizer wobble and had to disengage the autopilot. I wonder if the trucks crossed the beam? I forgot to ask the fire chief.had to stay high longer due to TCAS alert. I slowed rate of descent to avoid rcas. After the traffic passed I used boards to get down.MEL for bad pack on the side of the good engine. Made airflow path in case we lost the engine with the good pack. I could have used APU for pressurization and I would have if we were really single engine.I planned on using both engines in the event of a go around. And certainly would have used number two if anything happened to number one.didn't turn off stuff in the checklist since the engine was still running. I probably should have started the APU a little earlier (before we got to it in the checklist) although it was backup only.did a 20 flap landing at 151 knots. Very smooth just under max landing gross weight. Thrust reversers on both engines. Min auto brakes. Cleared runway. Stopped as requested then continued taxi to hangar gate and transloaded.great backup and initiative by the first officer. For example; when we shut down; he told me the stairs were on the wrong side for the MEL slide inop. And I was busier than normal with manual throttles and he assumed some of my duties in addition to his own. Very nicely done on his part.talked to fire chief. They have three levels of alert. I think it would be good info to incorporate in training. Cause: engine failed or went to idle; so quickly that I thought it had failed.

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Original NASA ASRS Text

Title: A300 flight crew reported returning to departure airport after Number 2 engine abruptly rolled back to idle.

Narrative: At FL200 Number 2 engine rolled back suddenly. All fuel pumps had been on since preflight. A lot of yaw and bank. Disconnected auto flight and throttles. Started descent. Checked engine rotating and turned on continuous relight. Left ECAM disappeared or diminished. Was it at idle or sub idle? I don't know. Lights but no horn. Checked that the engine responded to throttle movement then left it at idle and flew with auto throttles disconnected. Only used the engine for thrust reverse on landing and to taxi.Did the long checklist. Contacted ATC. They asked if we wanted the trucks ready or rolled. While I was thinking they made the decision. I would have rolled the trucks also. I think they could have gotten in place sooner as I had a lot of localizer wobble and had to disengage the autopilot. I wonder if the trucks crossed the beam? I forgot to ask the fire chief.Had to stay high longer due to TCAS alert. I slowed rate of descent to avoid RCAS. After the traffic passed I used boards to get down.MEL for bad pack on the side of the good engine. Made airflow path in case we lost the engine with the good pack. I could have used APU for pressurization and I would have if we were really single engine.I planned on using both engines in the event of a go around. And certainly would have used number two if anything happened to number one.Didn't turn off stuff in the checklist since the engine was still running. I probably should have started the APU a little earlier (before we got to it in the checklist) although it was backup only.Did a 20 flap landing at 151 knots. Very smooth just under max landing gross weight. Thrust reversers on both engines. Min auto brakes. Cleared runway. Stopped as requested then continued taxi to hangar gate and transloaded.Great backup and initiative by the FO. For example; when we shut down; he told me the stairs were on the wrong side for the MEL slide inop. And I was busier than normal with manual throttles and he assumed some of my duties in addition to his own. Very nicely done on his part.Talked to fire chief. They have three levels of alert. I think it would be good info to incorporate in training. Cause: Engine failed or went to idle; so quickly that I thought it had failed.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.