We tried using an APM 2.5 as a flight data recorder in a Cessna 208B. It was built into a 3D printed box with own power supply and recording done on a mobile phone.
There is one problem though: When the aircraft is in a steady bank the APM HUD indicates horizontal attitude as the resultant g-load is downwards relative to the APM. The difference between APM indicated attitude and aircraft artificial horizon is shown below. (Aircraft AH indicates about 30deg LH bank in top right corner)
UPDATE: THE PROBLEM SEEMS TO BE THAT ARDUCOPTER CODE WAS LOADED AND IT WAS FLOWN AS DISARMED, INSTEAD OF USING ARDUPLANE - THANKS DEVELOPERS!