On April 12, 1985, a Hiller UH12J3 (registration N545HA) operated by Western Helicopter Services, was involved in an aviation accident near Klamath, CA. Investigators recorded the probable cause as: A self-locking nut was missing and a bolt had backed out of the upper firewall bellcrank assembly, resulting in the loss of cyclic control. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter returning from a reconnaissance flight prior to a sprating operation lost cyclic control at about 10 ft AGL after flaring, causing rotor strike. Investigation found a missing self-locking nut and backed-out bolt in the upper firewall bellcrank assembly.
Incident Description
A helicopter was returning to a private landing pad after completing a reconnaissance flight prior to a sprating operation. During the approach, the pilot flared and leveled the aircraft at an altitude of approximately 10 feet above ground level. At that point, the pilot could no longer control a drift and roll to the left. Within about one second, the rotor blades struck the ground.
Investigation Findings
An investigation into the accident revealed that a self-locking nut was missing from the upper firewall bellcrank assembly. Consequently, a bolt had backed out of the assembly. This condition resulted in the loss of cyclic control, which prevented the pilot from correcting the aircraft's attitude and led to the rotor strike.
Probable cause
A self-locking nut was missing and a bolt had backed out of the upper firewall bellcrank assembly, resulting in the loss of cyclic control.
What happened in the 12 Apr 1985 Hiller UH12J3 accident near Klamath, CA?
A helicopter returning from a reconnaissance flight prior to a sprating operation lost cyclic control at about 10 ft AGL after flaring, causing rotor strike. Investigation found a missing self-locking nut and backed-out bolt in the upper firewall bellcrank assembly.
What aircraft was involved and where did it happen?
The accident on 12 Apr 1985 involved a Hiller UH12J3, registration N545HA, operated by Western Helicopter Services,, at Klamath, CA.
What was the probable cause of the accident?
A self-locking nut was missing and a bolt had backed out of the upper firewall bellcrank assembly, resulting in the loss of cyclic control.
A SkyWalk Join't 3 paraglider crashed into the ground near Las Vizcachas, Chile, on September 1, 2024. The pilot and passenger sustained serious spinal…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2024-09-01DGAC Chile
A Cessna 172N struck electrical cables while on final approach to land at Aucó Aerodrome in Chile. The pilot was uninjured, but the aircraft sustained damage…
A Bombardier DHC-8-402 suffered a tail strike during landing at Puerto Williams on September 9, 2024. All 76 occupants were unharmed, but the aircraft…
A MYD JS-MD 3 glider veered off the runway and struck a wall at Vitacura Aerodrome on January 6, 2025. The pilot was uninjured, but the aircraft sustained…
A recreational paraglider flight in Puchuncaví, Chile, ended with the pilot sustaining serious injuries after a rapid descent and impact with a hillside on…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2025-03-29DGAC Chile
A Tecnam P2006T landed on its belly at an aerodrome in Poland after the crew failed to confirm landing gear deployment. The incident resulted in no injuries…