Hydralic System Limitations on a Twin Otter
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Hydralic System Limitations on a Twin Otter
I was wondering if anyone would know the temperature limitions on the hydraulic oil of a twin otter. I understand that it is -40C but would like to confirm it if possible.
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Not sure what the end result you are looking for. The hydraulic fluid used in the Twotter is the standard general aviation red stuff MIL-H-5606. The Shell Oil web page (sorry, too compuker-illiterate to set up a hyperlink)says their version (Shell 4) has a pour point of below -75 F. The Canadian Operators Kenn Borek Air took a pair of Twotters down to the Antarctic mid-April this year, and had no reported problems in -68 C.
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Thanks T&B.
I may have missled you in the way I framed the question. I am after any Hydralic System temperature limitation on the Twotter.
Some aircraft will have for example a -40C limiation on the hyraulic system for operating the flaps or a rear cargo door. This is not a limitation on the ambient temperature or a limitation on the oil but a limitation on the hydraulic system itself and I would think it relates to the internal pressure of the system due to the viscosity of the oil at low temperatures and the chance of say blowing O-rings or seals.
I may have missled you in the way I framed the question. I am after any Hydralic System temperature limitation on the Twotter.
Some aircraft will have for example a -40C limiation on the hyraulic system for operating the flaps or a rear cargo door. This is not a limitation on the ambient temperature or a limitation on the oil but a limitation on the hydraulic system itself and I would think it relates to the internal pressure of the system due to the viscosity of the oil at low temperatures and the chance of say blowing O-rings or seals.
