As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EXCESSIVE TIMING DRIFT. BOTH MAGS SET 25 DEGREES BTDC ON NR1 CYLINDER. NEXT FIRING ORDER (NR 3 CYLINDER) IS OFF 6 DEGREES BETWEEN LT/RT MAG. NEXT FIRING ORDER (NR2 CYLINDER) IS NORMAL. LAST FIRING ORDER (NR4 CYLINDER) IS OFF 6 DEGREES BETWEEN LT/RT MAGS. INITIAL SUSPECT IS CAM LOBE. CARBON BRUSH INSPECTED IAW SB3-08. BRUSH SHOWS POSSIBLE INDICATION OF (EARLY STAGE) UNDERCUT. SLIGHT BRUSH RESIDUE EVIDENCED ON BEARING BAR.