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2 Answers

How is torque measured in Bell 204/205 helicopters?

Asked by: 1364 views ,
Aircraft Systems, Helicopter

Is the torque measured based off oil pressure?

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2 Answers



  1. Nibake on Jan 21, 2016

    This is going to be a crude answer.

    If this is a turbine powered helicopter I can tell you how torque is measured in a PT-6 and that may help you. It is not engine oil pressure. In the gear reduction there is a helical gear. Because the gears are ‘slanted’ with relation to each the more force applied to the driven gear the more it is forced back. Oil behind that driven gear resists this. The oil pressure resulting from that force applied to the driven gear is used to measure torque. Hope this helps. Maybe someone else can give you a more advanced description.

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  2. Abner on Mar 19, 2017

    It is gearbox oil pressure. Inside the reduction gearbox is a helical style gear that is able to “float” and move about it’s axis with changes in power/torque. This movement pushes oil in and out through an orifice and the torque is measured. The oil line in older helicopters may go straight to the gage in the cockpit, or has a transducer on the gearbox itself which turns the oil pressure measurement to an electrical signal to the gage.

    The newer technology aircraft measure torque through shaft twist/torsion and separation with a phonetic type sensor that then sends the signal.

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