Two questions: This AM at RSW we were informed that there would be a mechanical delay of 20 minutes. A mechanic went on board with the crew (only) and the E170 was pushed away from the gate. They taxied about 400-500 yards away and on four separate occasions, ran the engines up. The GA said that each time they were above 75% thrust. The plane then taxied back to the gate, we all boarded and took off 15 minutes later.

Can anybody tell me what they tested and how running up the engines resolved the problem?

Second question : As we were somewhere over Georgia at 36000' I was looking out the window and noticed the vertical winglet was covered from top to bottom with a thick coating of ice. The ice lasted until we started our decent over Indiana. It did not extend onto the wing itself. What effect does this have on flight and is this a concern? Thanks!