Gulfstream IV, Sugar Land, Texas, Nov. 11, 2007–The collapse of the GIV’s nosegear on landing at Sugar Land Regional Airport was due to shimmy stemming from improper installation of the upper torque arm pin by the flight crew during preflight, said the NTSB. After the GIV nosewheel touched down, the pilot felt a “violent vibration or shaking.” He applied full back force and the vibration eased but came back as the airplane slowed. No one was injured.