Airworthiness Directives; Boeing Model 737-100 and -200 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737-100 and -200 series airplanes, that requires repetitive inspections to find fatigue cracking in the main deck floor beams located at certain body stations, and repair, if necessary. This AD also provides for optional terminating action for the repetitive inspections. This AD is prompted by reports of incidents involving fatigue cracking and corrosion in transport category airplanes that are approaching or have exceeded their design life goal. This AD relates to the recommendations of the Airworthiness Assurance Task Force assigned to review Model 737 series airplanes, which indicate that, to assure long term continued operational safety, various structural inspections should be accomplished. The actions specified by this AD are intended to prevent failure of the main deck floor beams at certain body stations due to fatigue cracking, which could result in rapid decompression and consequent reduced controllability of the airplane.