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.

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.

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.