Narrative:

The pilot's seat belts in the twin cessnas bolt into the floor, whereas passenger belts are attached to the seats. As the seats are close together (for and aft), the passenger sitting behind the pilot's seats often put their feet on the belts, prior to where the belt attaches. They usually don't notice this and you have to tell people to move their feet in order to keep from being squeezed in two! I am so accustomed to this, that I usually just life the belt up from underneath the offending foot and the person gets the message. On this day, I grabbed the right half of the belt with my right hand, but right away I felt the belt go slack. I quickly looked at the buckle, but it was securely latched. With a sick feeling, I realized the belt was dangling in my right hand. I had always assumed that the belts were bolted into the floor. On inspection, however, I discovered that the belt end is a bolt screw which is screwed into a spot in the floor. After poking around in the carpet, I found the hole, screwed the belt back in, tugged on it for security, and proceeded to check the ends of the other belts. They all were several turns loose. Factors: over time, with passenger kicking the belts and crewmembers dropping them on the floor, picking them up again and twisting them back into proper position, the belts can work themselves out of their secured place. Periodic preflight inspections on their security can alleviate this potentially dangerous problem.

Related reports:

Google
 

Original NASA ASRS Text

Title: SEAT BELT ATTACHMENT BOLT CAME UNDONE.

Narrative: THE PLT'S SEAT BELTS IN THE TWIN CESSNAS BOLT INTO THE FLOOR, WHEREAS PAX BELTS ARE ATTACHED TO THE SEATS. AS THE SEATS ARE CLOSE TOGETHER (FOR AND AFT), THE PAX SITTING BEHIND THE PLT'S SEATS OFTEN PUT THEIR FEET ON THE BELTS, PRIOR TO WHERE THE BELT ATTACHES. THEY USUALLY DON'T NOTICE THIS AND YOU HAVE TO TELL PEOPLE TO MOVE THEIR FEET IN ORDER TO KEEP FROM BEING SQUEEZED IN TWO! I AM SO ACCUSTOMED TO THIS, THAT I USUALLY JUST LIFE THE BELT UP FROM UNDERNEATH THE OFFENDING FOOT AND THE PERSON GETS THE MESSAGE. ON THIS DAY, I GRABBED THE R HALF OF THE BELT WITH MY R HAND, BUT RIGHT AWAY I FELT THE BELT GO SLACK. I QUICKLY LOOKED AT THE BUCKLE, BUT IT WAS SECURELY LATCHED. WITH A SICK FEELING, I REALIZED THE BELT WAS DANGLING IN MY R HAND. I HAD ALWAYS ASSUMED THAT THE BELTS WERE BOLTED INTO THE FLOOR. ON INSPECTION, HOWEVER, I DISCOVERED THAT THE BELT END IS A BOLT SCREW WHICH IS SCREWED INTO A SPOT IN THE FLOOR. AFTER POKING AROUND IN THE CARPET, I FOUND THE HOLE, SCREWED THE BELT BACK IN, TUGGED ON IT FOR SECURITY, AND PROCEEDED TO CHK THE ENDS OF THE OTHER BELTS. THEY ALL WERE SEVERAL TURNS LOOSE. FACTORS: OVER TIME, WITH PAX KICKING THE BELTS AND CREWMEMBERS DROPPING THEM ON THE FLOOR, PICKING THEM UP AGAIN AND TWISTING THEM BACK INTO PROPER POS, THE BELTS CAN WORK THEMSELVES OUT OF THEIR SECURED PLACE. PERIODIC PREFLT INSPECTIONS ON THEIR SECURITY CAN ALLEVIATE THIS POTENTIALLY DANGEROUS PROB.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.