One of four ACH-47A attack helicopters assigned to "Guns-A-Go-Go". Tail number 64-13151, it was lost at Vung Tau in August of 1966 in a ground taxi accident when it collided with a CH-47 Chinook.
The name "Stump Jumper" derives from an accident during its an early mission in Vietnam where its underbelly was damaged by a collision with a tree stump following a forced landing.
Source: Frank White's "Guns-A-Go-Go" reunion site at http://www.atomic.net/~whitef/ and The Army Aviation Museum at http://www.armyavnmuseum.org/history/spotlight/gogo/gogo.html