The second of two prototypes, this Piasecki YH-16A Transporter broke apart in mid-air on 5 January 1956, when the rear rotor shaft failed, allowing the blades to desynchronize and wobble into the plane of those of the forward rotor. Although the cause of the failure was determined not to be a design defect the program was scrapped.
This photo was added on 31 December 2020, and has since been viewed 2179 times.