AD NUMBER: 2018-19-21

PRODUCT: All Boeing Model 707 airplanes, and Model 720 and 720B series airplanes.

ACTION: Final Rule.

SUMMARY: This AD was prompted by fuel system reviews conducted by the manufacturer.

This AD requires revising the maintenance or inspection program to include new airworthiness limitations.

DATES: This AD is effective November 1, 2018.

COST: The FAA estimates that this AD affects 9 airplanes of U.S. registry. The cost of compliance is estimated as follows:

Revising the maintenance or inspection program takes an average of 90 work-hours per operator, although this number may vary from operator to operator.

In the past, the FAA has estimated that this action takes 1 work-hour per airplane. Since operators incorporate maintenance or inspection program changes for their affected fleet(s), the FAA has determined that a per-operator estimate is more accurate than a per-airplane estimate. Therefore, the total cost per operator is estimated to be $7,650 (90 work-hours x $85 per work-hour).

FMI: AD