Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-600, -700, -800, -900, and -900ER series airplanes. This proposed AD was prompted by reports that certain seat track bolts were found with severed head bolts due to fatigue. This proposed AD would require replacing titanium seat track bolts with corrosion resistant steel (CRES) bolts, repetitive inspections for cracking of the splice strap and forward seat track holes, and related investigative and corrective actions if necessary. This proposed AD also provides an optional terminating action for the repetitive inspections. We are proposing this AD to detect and correct missing or severed bolt heads, which, if not corrected, could result in the inability of the seat track to carry passenger loads, which could cause the seats to detach from the seat track, resulting in possible injury to passengers during an emergency landing.