As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE ALTERNATE AIR VALVE IS VIBRATING AND CAUSING FRETTING BETWEEN THE INLET RING, PN D41-7166-20-31 AND FLANGE, PN D41-7166-20-33. THE "DUST" IS BEING INGESTED INTO THE FUEL CONTROL SERVO AND ENGINE. THERE NEEDS TO BE A TIGHTER FIT BETWEEN THESE PARTS.