As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHEN REPLACING THE REAR SHOULDER HARNESS INERTIA REEL ON THE C172, THE COVER BECAME DETACHED FROM THE ASSEMBLY AND THE RECOIL SPRING UNWOUND. IT CAME VERY CLOSE TO CAUSING INJURY TO THE AME. THE COVER APPEARED TO BE ATTACHED WITH GLUE ONLY IN 3 PLACES. WHEN IT WAS INSTALLED IN THE AIRCRAFT THE COVER WAS SECURED BY ATTACHING HARDWARE.