Temperature Limitations
Engineer 07 is correct.
When avionics equipment is designed it will normally be tested and certified to a TSO or TSO's. The TSO normally call up RTCA Minimum Performance Standards. The equipment is then built and demonstrated to meet the requirements of the specifications
The equipment is then considered for approval by the National Airworthiness Authorities based upon meeting these specifications.
RTCA/DO-160 "Environmental Conditions and Test Procedures for Airborne Equipment" specification that is called up by just about nearlly every TSO and it is here that you will find the temperature range of -55 C to +70 C.
The Aircraft Manufacture will apply a general Flight Manual temperature limitation upon the aircraft taken from RCA 160 of which is the limiting temperature factor that the equipment has been tested & certified to.
Regards having a suprise.... I think you may find a recent AAIB report regarding a certain Boeing 777 is currently of Interest where the temperature of the Fuel is being investigated.
Hope that has cleared that one up for you
Last edited by theavionicsbloke; 4th April 2008 at 23:12.