On December 13, 1984, a Hughes 369D (registration N58220) was involved in an aviation accident near Springville, UT. Investigators recorded the probable cause as: The pilot's failure to maintain visual reference during maneuvering in blowing snow, which resulted in loss of control and subsequent impact with the ground. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter lost visual reference due to blowing snow while maneuvering for a landing, resulting in the right skid striking the ground and the aircraft rolling onto its side.
What happened
The aircraft was being positioned at a remote site with the intention of picking up passengers. During the maneuvering phase required to establish a suitable landing spot, the pilot lost visual reference due to blowing snow conditions. The pilot reported feeling the right skid strike the ground and subsequently lowered the collective pitch control. Despite this input, the helicopter continued to roll until the main rotor blades made contact with the ground. The fuselage ultimately came to rest on its side.
The investigation
No specific mechanical examination details were provided in the source material regarding post-accident inspection of the airframe or rotor system beyond the description of the final resting position and contact points.
Findings
Contributing factors included the weather conditions which reduced visibility and the pilot's loss of visual reference during a critical maneuvering phase. The sequence of events indicates that despite corrective action taken by lowering the collective, the aircraft was unable to recover from the roll initiated by the skid contact.
Probable cause
The pilot's failure to maintain visual reference during maneuvering in blowing snow, which resulted in loss of control and subsequent impact with the ground.