As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FREQUENT FINDING OF LOW COMPRESSION ON EITHER FRONT OR REAR ENGINE WITH ONLY 808 HOURS TT. EACH TIME REPAIR WAS ACCOMPLISHED DUE TO THIS HISTORY, COMPLETE CYLINDER TEAR DOWN REVEALED EXCESS WEAR TO EXHAUST VALVES AND EXHAUST VALVE GUIDES. SUBMITTER SUSPECTS MFG DEFECT OR A MATERIAL INCOMPATIBILITY CAUSING ACCELERATED WEAR.