Casualties unknown

1992-09-05: Robinson R22 (N4073S) — Helicopters International — Alpine, TX

Alpine, TX, US

On September 5, 1992, a Robinson R22 (registration N4073S) operated by Helicopters International was involved in an aviation accident near Alpine, TX. Investigators recorded the probable cause as: Failure by the pilot-in-command, for unknown reasons, to maintain sufficient altitude to clear surrounding terrain. Factors were mountainous terrain and high density altitude. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 9 related events involving the same aircraft type or operator are linked below.

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

A helicopter on a cross-country flight over mountainous terrain impacted the side of a mountain at 6,800 feet, about 90 feet below the crest. The tail rotor struck first, and wreckage was distributed down to 6,500 feet. Investigation found no pre-impact mechanical failure.

Accident Overview

A helicopter was conducting a cross-country flight over mountainous terrain when it impacted the side of a mountain at an elevation of 6,800 feet, approximately 90 feet below the crest. The impact sequence began with the tail rotor striking the mountainside. Wreckage was dispersed downslope to about the 6,500-foot level.

Investigation Findings

Postaccident examination of the wreckage revealed no evidence of pre-impact flight control malfunction, airframe failure, or system failure. The engine was tested after the accident and performed within manufacturer specifications and certification standards.

Performance Calculations

Investigators calculated the density altitude at the accident site using a pressure altitude of 6,800 feet and an estimated temperature of 85 degrees Fahrenheit, resulting in a density altitude of 9,900 feet. The helicopter's gross weight at the time of the accident was calculated to be 1,229 pounds. For that density altitude, the maximum gross weight for out-of-ground effect hover performance was determined to be 1,210 pounds.

Pilot and Witness Information

The pilot had no memory of the accident. There were no witnesses, and the phase of operation at the time of impact is unknown.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20170710X10920. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.