Cliff notes: this accident was caused by bent linkage in the series yaw damper (prevents Dutch roll) and lack of crew awareness in Dutch roll recovery. As the aircraft accelerated, so did the Dutch roll.. the crew knew something was wrong but couldn't figure out what was going on... there were indications that the AC (aircraft commander) suspected the yaw damper was the issue, but at the time, corrective action was to turn the yaw damper back ON, since it fails in the OFF mode. But in this case, the yaw damper worked fine, it was just the linkage that made the rudder out of sync, causing the Dutch roll rather than dampening it as designed.
This accident scared them hell out of us in the 135 community, because for months no one knew wtf happened. I was under the strong opinion that the center wing fuel tank exploded like TWA800...
I always try to put myself in the crew's shoes and think honestly what I would have done..... to tell the truth, I don't think I would have figured out the problem, but I do think that ONE thing would have saved me... I would have slowed the fuck down! And especially stayed off the rudder. The fact that they kept accelerating, and worse yet, made rudder inputs coupled with improper Dutch roll recovery, sealed their fate. Very sad.
My sim partner in CFIC was roommates with the copilot's husband at the academy... she (the copilot) just returned from maternity leave and was just back on flying status. He also was a 135 guy and never flew the tanker again after the incident.