Narrative:

Upon liftoff we experienced a significant uncommanded aircraft roll. I was the pilot flying; and I countered this roll with nearly full aileron. The aircraft then rolled in the opposite direction which I again countered with aileron. The rolling action ceased above 25' to 50' AGL. This roll definitely caught our attention as it was more pronounced than either of us had experienced before.after stabilizing the aircraft in climb; gear and flaps up; we discussed probable causes for the roll. We discussed flap asymmetry; blown tire; thrust reverser deployment; spoiler deployment; but at the time all systems appeared to be operating normally. We also discussed a gust of wind; but the roll was more than either of us had ever experience so we ruled that out as well.during further climb; I recalled that as we were taxiing to [the runway]; a company aircraft was taxiing west towards the company maintenance hangar. We discussed the possibility that the aircraft was performing an engine run and we flew through the jet blast. The first officer called back to ground control and they confirmed that indeed a company aircraft was performing an engine run in the vicinity.we concluded that we had flown through the jet blast of the aircraft performing the maintenance engine run and continued uneventfully.both company maintenance and ground and tower control should have been aware of the hazards of jet blast on runway operations. They should (at a minimum) have communicated to us that the hazard existed for jet blast from the engine run; and possibly delayed our takeoff until the engine run was complete. We were told by tower to expedite our takeoff roll and the frequency was quite busy. Conditions were dark; so we never saw the aircraft doing the engine run. I feel that this was a communication breakdown for all parties. Ground control obviously knew of the engine run; and the fact that the jet blast was pointed directly at our departure runway. Either this was never communicated to the tower controller; or the tower controller did not see fit; or was too busy to communicate it to us. Fortunately our aircraft was a non-scimitar aircraft; as we believe that the roll was so pronounced that we would have dragged a wingtip if we had scimitars installed.

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Original NASA ASRS Text

Title: B737-700 Captain reported significant uncommanded roll in both directions on initial climb related to jet blast from an aircraft on the ground performing an engine run for maintenance.

Narrative: Upon liftoff we experienced a significant uncommanded aircraft roll. I was the Pilot Flying; and I countered this roll with nearly full aileron. The aircraft then rolled in the opposite direction which I again countered with aileron. The rolling action ceased above 25' to 50' AGL. This roll definitely caught our attention as it was more pronounced than either of us had experienced before.After stabilizing the aircraft in climb; gear and flaps up; we discussed probable causes for the roll. We discussed flap asymmetry; blown tire; thrust reverser deployment; spoiler deployment; but at the time all systems appeared to be operating normally. We also discussed a gust of wind; but the roll was more than either of us had ever experience so we ruled that out as well.During further climb; I recalled that as we were taxiing to [the runway]; a Company aircraft was taxiing west towards the Company Maintenance hangar. We discussed the possibility that the aircraft was performing an engine run and we flew through the jet blast. The First Officer called back to Ground Control and they confirmed that indeed a Company aircraft was performing an engine run in the vicinity.We concluded that we had flown through the jet blast of the aircraft performing the maintenance engine run and continued uneventfully.Both Company Maintenance and Ground and Tower Control should have been aware of the hazards of jet blast on runway operations. They should (at a minimum) have communicated to us that the hazard existed for jet blast from the engine run; and possibly delayed our takeoff until the engine run was complete. We were told by Tower to expedite our takeoff roll and the frequency was quite busy. Conditions were dark; so we never saw the aircraft doing the engine run. I feel that this was a communication breakdown for all parties. Ground Control obviously knew of the engine run; and the fact that the jet blast was pointed directly at our departure runway. Either this was never communicated to the Tower Controller; or the Tower Controller did not see fit; or was too busy to communicate it to us. Fortunately our aircraft was a non-scimitar aircraft; as we believe that the roll was so pronounced that we would have dragged a wingtip if we had scimitars installed.

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.