"Black Hawk Down" by Mark Bowden was the book immortalized as "Black Hawk Down." "In the Company of Heroes" is the autobiography of the US pilot who was downed and held captive for a while.
Durant explains that the "centrifugal" force caused by the tail rotor failure prevented the co-pilot from reaching up and cutting the power levers (mounted on the overhead in the Blackhawk). It is an interesting point that you raise, though. They knew they'd been hit near the TR, so it is surprising the PNF wasn't "covering" the power levers just in case... Hindsight's 20/20.