This MOSFET is from a good board for an RC plane. On a bad board, the MOSFET is completely fried and the number is not visible. The MOSFET drives a motor, and the motor stalled during a crash repair, which caused the MOSFET to pop, as well as damaging a diode (probably the catch/flywheel diode as it is across the motor.) In future, I will add a fast blow ~10A fuse to the motor line to protect the MOSFET.
I can replace the diode with any fast Schottky but I need to know the ratings of the MOSFET and I cannot find a datasheet anywhere. I suspect the pin out is gate, drain, source from left to right, but I cannot be certain. I'm not even sure if it is actually a MOSFET; for all I know, it could be a power NPN transistor. It has no heatsink on it (likely what caused it to fry when the motor stalled) and looks like a TO263 package. The numbers on it are "U438" and "BA8112".