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A quick follow up post about the probable cause of this tragic helicopter crash. After seeing the photos of the transmission that was recovered from the Hudson River, there was an unmistakable hole in the side of the cast housing of the transmission and I believe you’re going to hear when the investigation is complete that there was a complete failure of the internal gears which instantly locked up the main rotor shaft. The torque from the main rotors created enough shear to completely tear away the top deck of the helicopter. None of the mounting arms or brackets failed! The seizing of the internal gears not only burst fragments out of the side of the transmission housing, but it tore the entire roof off of the fuselage, opening the top of the cabin. The shock of the torque also instantly ripped away the entire tail boom at the same time.
Transmission housings have sight glasses and chip sensors to help ensure there is sufficient gear oil that it is free of metal particles and fragments that can indicate some gear deterioration. The magnetic chip sensor will give a light in the cockpit to inform the pilot that there is metal in his gear oil. Since there was no report by the pilot of a chip light issue, the gear failure is something that must have happened instantly & catastrophically; without any warning.
Of course this is my own interpretation based on all the video and photo evidence that has been published. But there are very few things that would have caused such a complete failure of the main rotor drive system and a midair disintegration of that aircraft. If my assumption is not similar to the final report by the NTSB, I will be very curious to know what else would have cause the type of destruction we saw in this instance. It is so sad that a skilled pilot and an entire family perished in an accident that no one could have known was about to happen. No doubt all the Part 135 operators around the country who employ helicopters will be all over their maintenance logs to ensure those gear boxes are up to date on all the manufacturer’s service requirements.
Transmission housings have sight glasses and chip sensors to help ensure there is sufficient gear oil that it is free of metal particles and fragments that can indicate some gear deterioration. The magnetic chip sensor will give a light in the cockpit to inform the pilot that there is metal in his gear oil. Since there was no report by the pilot of a chip light issue, the gear failure is something that must have happened instantly & catastrophically; without any warning.
Of course this is my own interpretation based on all the video and photo evidence that has been published. But there are very few things that would have caused such a complete failure of the main rotor drive system and a midair disintegration of that aircraft. If my assumption is not similar to the final report by the NTSB, I will be very curious to know what else would have cause the type of destruction we saw in this instance. It is so sad that a skilled pilot and an entire family perished in an accident that no one could have known was about to happen. No doubt all the Part 135 operators around the country who employ helicopters will be all over their maintenance logs to ensure those gear boxes are up to date on all the manufacturer’s service requirements.
