AD NUMBER: 2018-09-13

PRODUCT: All Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes.

ACTION: Final Rule.

SUMMARY: This AD was prompted by reports indicating additional cracking in the inspar upper skin at wing buttock line (WBL) 157 and in the skin at two holes common to the rear spar in the same area, and rear spar web cracks were also noted on both wings.

Subsequent inspections revealed that the right rear spar upper chord was almost completely severed and the left rear spar upper chord was completely severed. Additional reports identified cracking in the main landing gear (MLG) beam forward support fitting.

This AD requires the installation of standard-size fasteners for a certain configuration and inspections for any crack in certain locations of the rear spar.

DATES: This AD is effective June 19, 2018.

COST: The FAA estimates that this AD affects 471 airplanes of U.S. registry. The estimated costs of compliance include:

• HFEC open hole inspections - $6,970 per aircraft per inspection cycle
• Eddy current inspection - $1,190 per aircraft per inspection cycle
• Optional Inspection -  $3,485 per aircraft per inspection cycle

FMI: AD