Thank you very much!
Be sure you don't keep the speed brake switch depressed. Release the switch after using it. The airplane keeps trimming while the speed brake switch is depressed.
Don't know if this is the reason why that happened to you but, the engine can catch fire if you keep an ITT higher than 831ºC for more than 5 minutes in the C-101EB. Or, there's a failure programmed in the mission, of course.