Narrative:

On route to our destination ZZZ airport; we started to accumulate ice at FL270. The captain proceeded to switch on both engine anti-ice switches as well as airframe anti-ice. A couple seconds later our left engine began to roll back. About a minute or so after that; the right engine began surging but did not roll back completely. We then [requested priority handling] and asked ATC for help to the nearest suitable airport. We then were cleared to descend to 11;000 ft. I started my descent and tried to keep the right engine turning by keeping a low power setting. Meanwhile; the left engine kept surging so I pulled the left throttle to flight idle. While in the descent the captain ran the emergency checklist items and handled communications with ATC. ATC then cleared us to descend to 4000 ft. And vectored us for the ILS runway xx at ZZZ. Passing through 10;000 ft. We noticed that the right engine had stabilized and was able to provide sufficient power for landing while the left engine would also provide sufficient power at a lower power setting. The landing phase was uneventful.

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Original NASA ASRS Text

Title: Falcon 20 First Officer reported a dual engine rollback while encountering icing conditions; which required a descent and diversion to the nearest suitable airport.

Narrative: On route to our destination ZZZ Airport; we started to accumulate ice at FL270. The Captain proceeded to switch on both Engine anti-ice switches as well as airframe anti-ice. A couple seconds later our left engine began to roll back. About a minute or so after that; the right engine began surging but did not roll back completely. We then [Requested Priority Handling] and asked ATC for help to the nearest suitable airport. We then were cleared to descend to 11;000 ft. I started my descent and tried to keep the right engine turning by keeping a low power setting. Meanwhile; the left engine kept surging so I pulled the left throttle to flight idle. While in the descent the Captain ran the emergency checklist items and handled communications with ATC. ATC then cleared us to descend to 4000 ft. and vectored us for the ILS Runway XX at ZZZ. Passing through 10;000 ft. we noticed that the right engine had stabilized and was able to provide sufficient power for landing while the left engine would also provide sufficient power at a lower power setting. The landing phase was uneventful.

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.