As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE BS 1342, RBL 18 CHANNEL WAS FOUND SEVERELY RUSTED WHERE IT ATTACHES TO THE STRUCTURE. DEFECT WAS DISCOVERED DURING A RE-ENGINING MODIFICATION. THIS CONDITION HAS BEEN FOUND ON ALL 38 AIRCRAFT MODIFIED THUS FAR. CONDITION IS PROBABLY CAUSED BY DISSIMILAR METAL AND LACK OF DRAINAGE. NOTE: THE RUST CANNOT BE SEEN WITHOUT REMOVING THE PART, MAY NEED TO BE X-RAYED EVERYY SO MANY YEARS.