Originally Posted by Jazz Hands
METAR says the temperature at LHR was 25C at the time the alarm was raised. Given that heat rises, anyone want to hazard a guess at how warm it becomes just under the crown of a non-insulated fuselage skin which has been baking for the entire day?
And does anyone else leave their 787s outside for a similar time, in similar heat, or do they return to the cool high altitude too regularly?
According this
Honeywell Rescu 406 AFN2 Brochure, the storage temperature range of the ELT is -55 to +85 Celsius. I could well imagine it getting close to that if not higher if in direct sunlight for long enough. The upper end of the operating temperature range is specified to be lower, 55 Celsius, which I would have thought easily achievable.
Various studies on car interior temperatures, where vehicles are closed up and left in the sun show startling high temperatures. Temperatures for the air alone can be as high as 50 Celsius. Surfaces (especially dark surfaces) inside vehicles tend to be much hotter, as this is the source of heat for warming the air. Dashboards are known to reach about 100 Celsius.
If there is any comparison here, without insulation for the ELT, I would have thought the installation site unsuitable in this instance.