Casualties unknown

2007-11-11: Gulfstream Aerospace G-IV (N209LS) — Avn Air Llc — Sugar Land, TX

Sugar Land, TX, US

On November 11, 2007, a Gulfstream Aerospace G-IV (registration N209LS) operated by Avn Air Llc was involved in an aviation accident near Sugar Land, TX. Investigators recorded the probable cause as: The nose landing gear collapsed and separated due to shimmy, which developed when the torque link connection to the nose wheel steering/damper unit separated as a result of improper installation of the nose landing gear upper torque arm pin by the flight crew… This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

Following an uneventful touchdown, the nose landing gear collapsed due to violent shimmy. Investigators determined that the shimmy resulted from improper installation of the upper torque arm pin by the flight crew during the last preflight inspection.

Accident Overview

The pilot reported that the flight, approach to landing, and touchdown were uneventful. Soon after the nose landing gear touched down, the ground spoilers deployed automatically and the thrust reversers were activated. The pilot then experienced a violent vibration or shaking. Full back pressure was applied to the control yoke, which eased the vibration until the aircraft slowed further, at which point the vibration returned. The nose landing gear subsequently collapsed to the right side, and the aircraft skidded to a stop.

Recorded Data

The cockpit voice recorder (CVR) and flight data recorder (FDR) were recovered following the incident. The CVR provided no significant information related to the event. Data from the FDR indicated that the landing touchdown was not heavy and did not involve excessive drift. The deceleration of the aircraft increased within seconds of touchdown, consistent with the deployment of spoilers and thrust reversers.

Post-Accident Examination

Damage was confirmed to the forward pressure vessel. Both nose landing gear tires remained inflated throughout the collapse. The nose gear assembly was shipped to Gulfstream facilities for further examination and analysis. Examination of the nose landing gear revealed that the collapse 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. This separation occurred due to the improper installation of the nose landing gear upper torque arm pin by the flight crew during the last preflight inspection of the aircraft.

Probable cause

The nose landing gear collapsed and separated due to shimmy, which developed when the torque link connection to the nose wheel steering/damper unit separated as a result of improper installation of the nose landing gear upper torque arm pin by the flight crew during the last preflight inspection.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20071127X01856. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.