[greglepore]

The first comment down quotes some site that indicates it was a prepeg aramid patch, which I guess is feasible.

I have a friend that flew an older Citaition back from Costa Rica with a duct tape repair over the leading edge of a wingtip after the FBO there bumped and damaged it when moving an adjacent aircraft. I thought he was nuts at the time, but it turned out to be effective and harmless.