Prompted By Numerous Reports That Proximity Sensors Have Failed

The FAA has posted a proposed AD for Boeing's 787-8 Dreamliner to the Federal Register after reports of numerous failures of the proximity sensor within the slat skew detection mechanism assembly (DMA) leading to slats-up landing events.

The proposed AD would require replacing the slat skew DMAs with new slat skew DMAs, and marking the existing identification plates on the slat with the new part number. The FAA is proposing this AD to prevent failure of the proximity sensor, which could result in the slats being shut down and a slats up high speed landing.

This condition, in combination with abnormal landing conditions such as a short runway or adverse weather conditions, could result in a runway excursion, the agency says.

Comments for the AD will be accepted for 45 days following its November 28 publication.

The FAA estimates that the cost of compliance with the AD for the 15 airplanes of U.S. registry to be $14,025.

Reuters reports that Boeing is supporting the proposed rule, and that in March it recommended that the mechanism be replaced on all 132 787-8s in service worldwide. About a third have already been retrofitted, the planemaker said.

FMI: Proposed AD