There's a letter (SB?) from Pratt about runaway JT8Ds as found on -200s. There is a shaft from the N2 section supplying feedback to the FCU. If the shaft fails, the FCU goes to a preset setting which IIRC on twin engine planes is 100%. There had been 30 some cases of the failure mode in the mid 90s when the letter came out.
I recall that the concern in cases like this was the flight condition when this could happen. If during takeoff roll the pilot's natural action would be a sensed engine out and attempt to correct accordingly. Unfortuately this could rapdidly take the plane off the runway before they would realize that they had to chop the throttle on the bad engine. I believe that a fatal crash was attributed to this in Saudi.
The other bad news condition would be landing.
This kind of problem can not be eliminated, although minimized and can occur on all engines that I am familar with albeit for different reasons.