AD NUMBER: 2018-01-06

PRODUCT: Certain Fokker Services B.V. Model F28 Mark 0070 and 0100 airplanes.

ACTION: Final Rule; request for comments.

SUMMARY:  This AD requires contacting the FAA to obtain instructions for addressing the unsafe condition on these products, and doing the actions specified in those instructions.

This AD was prompted by a report of an engine multiple fan blade release event. According to EASA, a Tay 620 engine multiple fan blade release event recently occurred on an F28 Mk. 0070 aeroplane. As a result, low energy fan blade fragments exited the engine by penetrating the engine nose cowl.

Although the investigation is still on-going, one of the findings was an incorrect adjustment of the (emergency) maximum reverse thrust stop. Consequently, attempts to select (emergency) maximum reverse thrust led to stabilized engine operation in an N1 speed range that, in combination with other contributing factors, may have caused high fan blade stresses due to flutter.

DATES: This AD becomes effective January 22, 2018. Comments must be received by February 20, 2018.

COST: The FAA estimates that currently, there are no affected U.S.-registered airplanes. For an affected airplane that is placed on the U.S. Register in the future, the cost of compliance would be $510 per aircraft for inspection and $85 for reporting to the FAA.

FMI: AD