Given that retracting a landing gear that happens to be on fire is a suicidally bad idea, for reasons that should be immediately obvious, do airplanes have temperature sensors on their landing gear in order to detect landing gear fires and prevent burning landing gear from being retracted?
1 Answer
There are fire detection heat sensing loops in the gear well. If a gear was on fire it would trigger a "GEAR OVERHEAT" message and warning when the gear was up. There are no retraction prevention systems that are able to detect fires at the gear. Nationair was a unique series of clusterflarks leading to the accident, on top of the fact that the magnesium wheels started to burn. Modern magnesium alloys don't do that.
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$\begingroup$ By the time the flaming gear is in a position to trigger the GEAR OVERHEAT warning, it's already in close contact with the flammable hydraulic lines in the well, which will shortly ignite the fuel tanks above the well, and your aircraft is already doomed. $\endgroup$– VikkiDec 10, 2018 at 3:44
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2$\begingroup$ I added a line to cover the magnesium factor. The DC-8 had old magnesium wheels and in those days they could catch fire if heated sufficiently (like scraping along pavement at 130 kt) and the resulting fire is intensely hot and can't be blown out. This doesn't happen with modern alloys and a rubber fire wouldn't sustain itself at flying speed. The bottom line is that the risk of a Nationair type event on modern aircraft is too microscopic to require mandating a system like that. $\endgroup$– John KDec 10, 2018 at 4:05