On March 17, 2000, a Hiller UH-12B (registration N5304V) operated by Robert Kivlen was involved in an aviation accident near Sanford, FL. Investigators recorded the probable cause as: The pilot's improper collective and cyclic control usage during an emergency descent, following the onset of a 1 to 1 vibration for undetermined reasons, resulting in the helicopter landing hard and rolling over. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced vibration after takeoff, leading to control loss during approach. Post-crash inspection found a loose magneto lead but no other mechanical defects.
Accident Sequence
During the climb phase after takeoff, the pilot noticed a vibration described as a 1-to-1 oscillation. He responded by lowering the collective and starting an approach toward the surface. The vibration intensified as the helicopter descended. When the pilot raised the collective near the ground, the helicopter gave no apparent response to the control input. The helicopter then impacted the ground heavily and rolled onto its side.
Post-Crash Examination
Post-accident examination by an FAA inspector revealed no obvious mechanical defects in the rotor blades or flight control systems. However, the left engine magneto's 'P' lead was found to be loose. This condition rendered the magneto inoperative. The threads on the 'P' lead were undamaged, and the magneto itself was not damaged from the impact.