What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
The flight instructor and student were returning to the home airport after successful cross wind training at tulsa international airport (ktul). The instructor aided the student throughout the final approach to O38. The aircraft landed normally and on initial brake application the instructor stated a loud "pop" was heard. The right wing began to drop due to the separation of the r/h gear strut from the main spar. The aircraft drifted right of centerline on the end of the roll-out resulting in the r/h wing in the grass off of the asphalt surface.
Upon investigation all eight 1/4" an fasteners had failed allowing r/h main strut separation. No bolt hole were torn or exhibited failure evidence. This aircraft is a training aircraft and has a significant amount of flight time. From the evidence of the limited fasteners retrieved it appears fatigue may have been a factor.
As the FAA filed it
THE FLIGHT INSTRUCTOR AND STUDENT WERE RETURNING TO THE HOME AIRPORT AFTER SUCCESSFUL CROSS WIND TRAINING AT TULSA INTERNATIONAL AIRPORT (KTUL). THE INSTRUCTOR AIDED THE STUDENT THROUGHOUT THE FINAL APPROACH TO O38. THE AIRCRAFT LANDED NORMALLY AND ON INITIAL BRAKE APPLICATION THE INSTRUCTOR STATED A LOUD "POP" WAS HEARD. THE RIGHT WING BEGAN TO DROP DUE TO THE SEPARATION OF THE R/H GEAR STRUT FROM THE MAIN SPAR. THE AIRCRAFT DRIFTED RIGHT OF CENTERLINE ON THE END OF THE ROLL-OUT RESULTING IN THE R/H WING IN THE GRASS OFF OF THE ASPHALT SURFACE.
UPON INVESTIGATION ALL EIGHT 1/4" AN FASTENERS HAD FAILED ALLOWING R/H MAIN STRUT SEPARATION. NO BOLT HOLE WERE TORN OR EXHIBITED FAILURE EVIDENCE. THIS AIRCRAFT IS A TRAINING AIRCRAFT AND HAS A SIGNIFICANT AMOUNT OF FLIGHT TIME. FROM THE EVIDENCE OF THE LIMITED FASTENERS RETRIEVED IT APPEARS FATIGUE MAY HAVE BEEN A FACTOR.