LAX04FA067 · Robinson R22 Beta

The helicopter crashed vertically in a city street during an autorotation following a loss of engine power. The pilot was on his second logged flight since obtaining his rotorcraft rating and was on a solo cross-country flight when witnesses reported hearing the engine miss-fire and then quit. The witnesses saw the helicopter's main rotor blades coning up and then stop rotation completely. The helicopter fell straight down to a city street below. The magneto switch was found in the off position with no sign of impact damage to the switch or key. An evaluation of the crash dynamics, the force vectors involved, and the structural deformation of the helicopter could not explain the magneto switch position. Witnesses to the accident said the magneto switch was not turned off by anyone after the accident. Examination of the engine and helicopter systems found no anomalies that would have prevented their normal operation. The engine roughness heard by the witnesses coupled with the magneto switch position may indicate that the pilot was attempting to diagnose an engine roughness by selectively turning off one magneto at a time and in the process, he may have inadvertently selected the both off position. The pilot was in the right seat and manipulation of the magneto switch would have required him to take his hand off the collective, which could have resulted in a delay in reacting to the loss of engine power. Toxicology reports on the pilot showed that chlorpheniramine was detected in blood at a level several times higher than the level expected with a typical maximum single over-the-counter dose of the medication. Chlorpheniramine is an over-the-counter sedating antihistamine commonly used for cold and allergy symptoms and is present in many over-the-counter multisymptom preparations. In typical doses, the medication has measurable adverse effects on performance of complex cognitive and motor tasks. It is likely that the pilot's performance and judgment were impaired by chlorpheniramine. The Federal Aviation Administration instructs Aviation Medical Examiners that, "any airman who is undergoing continuous treatment with... sedating antihistaminic...drugs... must be deferred certification..."

Verbatim NTSB analysis and probable cause from the NTSB dataset