On November 11, 2007, at 1021 central standard time, a Gulfstream Aerospace G-IV twin-turbofan airplane, N209LS, was substantially damaged when the nose landing gear collapsed while landing on Runway 17 at the Sugar Land Regional Airport (KGSR), near Sugar Land, Texas. The 14 Code of Federal Regulations Part 91 business flight originated from Baton Rouge, Louisiana, with planned intermediate stops at Sugar Land, Texas, and Montrose, Colorado, with a final destination of Monterey, California. The flight crew of 3 and 5 passengers were not injured and evacuated unassisted through the main cabin door. In a written statement, the pilot reported that the flight, approach to landing and touchdown were uneventful. Soon after touchdown, when the nose landing gear touched down, the ground spoilers deployed automatically and the thrust reversers were deployed. The pilot then stated: " When the nose wheels touched down, a violent vibration or shaking was felt, full back force was applied to the control yoke and the vibration eased until the aircraft slowed further and the vibration returned. The nose landing gear collapsed to the right side of the nose and the aircraft skidded to a stop." The airplane was recovered to a secured hangar at KGSR and a preliminary investigation was conducted by representatives from the Federal Aviation Administration and Gulfstream Aerospace. Damage was confirmed to a forward pressure vessel. Both nose landing gear tires remained inflated through the collapse. The nose gear assembly was shipped to Gulfstream facilities for further examination and analysis. The cockpit voice recorder (CVR) and flight data recorder (FDR) were recovered following the accident. No significant information concerning the event was obtained from the CVR. The data from the FDR indicated that the landing touchdown was not heavy or with excessive drift. The data also indicated that the deceleration of the aircraft increased within seconds of the touchdown consistent with spoiler and thrust reverser deployment. The Sugar Land Airport is owned and operated by the City of Sugar Land. The airport features a single concrete surfaced runway. Runway 17 is 8,000-feet long and 100-feet wide. Examination revealed that the nose landing collapsed and separation were the result of nose landing gear shimmy. The shimmy developed when the torque link connection to the nose wheel steering/damper unit separated as the result of the improper installation of the nose landing gear upper torque arm pin by the flight crew during the last preflight inspection of the aircraft. Weather reported at KGSR approximately 25 minutes prior to the landing on runway 17, was winds from 160 degrees at 10 knots, clear skies, 10 miles visibility, temperature of 26 degrees Celsius, dew point 18 degrees Celsius, with an altimeter reading of 30.07 inches of Mercury.