Summary
We propose to supersede Airworthiness Directive (AD) 2017-25- 12, which applies to all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. AD 2017-25-12 requires repetitive inspections for cracking of the webs of the stub beams at certain fuselage stations, and applicable on-condition actions. Since we issued AD 2017-25-12, we have received reports of horizontal cracking in the station (STA) 685 stub beam at the inboard end of the upper chord and the outboard end of the lower chord. AD 2017-25-12 did not require an inspection of the area where the horizontal cracks were found. This proposed AD would require repetitive inspections at certain fuselage stations for cracking of the stub beams, and applicable on- condition actions. We are proposing this AD to address the unsafe condition on these products.