AD NUMBER: 2018-22-03

PRODUCT: Certain Bombardier, Inc., Model DHC-8-400 series airplanes.

ACTION: Final Rule.

SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2016-24-03, which applied to the aircraft listed above.

AD 2016-24-03 required repetitive detailed inspections of barrel nuts and cradles, a check of the bolt torque of the preload indicating (PLI) washers, and corrective actions if necessary.

This AD retains the requirements of AD 2016-24- 03 and requires modifying the airplane by installing a sealing disk to a certain location and replacing certain barrel nuts.

This AD was prompted by reports of cracked and corroded barrel nuts found at the mid-spar location of the horizontal-stabilizer-to-vertical-stabilizer attachment joint, and the issuance of new service information that includes a terminal modification.

DATES: This AD is effective November 28, 2018.

COST: The FAA estimates that this AD affects 54 airplanes of U.S. registry. Operators may incur the following costs in order to comply with this AD:

• Inspections (retained actions from AD 2016-24-03) - 8 work-hours × $85 per hour = $680.
• Sealing disk installation (new action) - 4 work-hours × $85 per hour = $340. Parts - $781. Total cost per airplane - $1,121.
• Replacement of DSC228 series barrel nuts (new action) - 2 work-hours × $85 per hour = $170. Parts - $2,236. Total cost per airplane - $2,406.
• Replacement (retained action from AD 2016-24-03) - 2 work-hours × $85 per hour = $170. Parts - $8,881. Cost per product - $9,051.

FMI: AD