Mine was a Chinook that had one Engine runaway up....that would not respond to the published procedure....and a cloud deck at only 5,000 feet above me. Upon loading the rotor system with Collective....I then had two engines at Max or More than Max power. The only difference was the Ng speeds which had one at Topping....and one well beyond Topping! Talk about being on a Runaway Express Elevator! Smack dab in the middle of that small deviation from normal....we had to add IIMC....me with two students who between them had three hours of Chinook experience.
My Beer tasted very good that evening....despite being very foamy from all the shaking my hand was doing!