AD NUMBER: 2017-20-05

PRODUCT: Certain Boeing Model 757-200, -200CB, and -300 series airplanes.

ACTION: Final Rule.

SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2011-01-15, which applied to the aircraft listed above.

AD 2011-01-15 required repetitive inspections for cracking of the fuselage skin of the crown skin panel along the chem-milled step at certain stringers, and repair if necessary.

This AD adds repetitive inspections for cracking in additional areas, and repair if necessary; removes airplanes from the applicability; adds an optional skin panel replacement, which terminates all inspections; adds an optional preventive modification, which terminates certain inspections; and reduces the compliance time for certain inspections.

This AD was prompted by reports of the initiation of new fatigue cracking in the fuselage skin of the crown skin panel along locally thinned channels adjacent to the chem-milled steps.

COST: The FAA estimates that this AD affects 652 airplanes of U.S. registry. The cost of compliance is estimated to be $170 per inspection cycle per airplane for inspection of Zone 1; up to $340 per inspection cycle per airplane for inspections of Zones 2 and 3, and; up to $78,771 per aircraft for optional modifications.

DATES: This AD is effective November 6, 2017.

FMI: AD