What was found
AT THE 1,000-HOUR STRUCTURAL INSPECTION BEING DONE BY UNITED BEECHCRAFT ONTARIO, FINDING CRACKS IN THE FRAME AT STATION 107.000 FRAME, PN 102-430241-1, AT THE END OF SPLICE, PN 102-430196-3. ALL THE AIRCRAFT THAT ARE BEING FOUND WITH CRACKS ARE IN THE 300 S/N'S AND HAVE 4 MISSING RIVETS. THE AIRCRAFT WITH S/N IN THE 400 SERIES HAVE RIVETS INSTALLED AND NO CRACKS. THE 1,000-HOUR STRUCTURAL INSPECTION IS A REQUIRED INSPECTION BY THE U. S. FOREST SERVICE ON THEIR BARON 58P'S.