Who knows.
There is many a passenger in a car who subconsciously presses hard on the footwell when they think the driver is too close to the car in front, without saying anything about it (the imaginary brake).
Conversely, if it was a braking system fault, then what could cause brakes to come on uncommanded? It is not a usual system failure. Does the Yak have autobrakes?
Another possibility might be a brake that was binding from the beginning, but the problem worsened as it got hotter. A brake would need to be on for some time, or on very hard, to get enough energy to burst into flames.
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Last edited by silverstrata; 20th Sep 2011 at 18:45.