AD NUMBER: 2017-17-03

PRODUCT: MD Helicopters, Inc. (MDHI), Model MD900 helicopters.

ACTION: Final Rule.

SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2014-16-01 for the aircraft listed above.

AD 2014-16-01 required an eddy current inspection of the main rotor upper hub assembly (upper hub) for a crack.

This AD requires additional inspections and replacing the fillet seal. This AD was prompted by three additional reports of upper hub cracks.

MDHI has issued Service Bulletin SB900-125, dated February 19, 2016, which describes procedures for repetitive visual and eddy current inspections of the upper hub upper and lower flexbeam bolthole areas and for applying a fillet seal on the interface of the bushing and the flex beam retention bolt hole.

DATES: This AD is effective September 25, 2017.

COST: The FAA estimates that this AD affects 23 helicopters of U.S. Registry. At an average labor rate of $85 per hour:

Inspecting the fillet seal around the flexbeam boltholes (100 hour TIS inspection) requires about 1 work-hour, for a cost per helicopter of $85 and a cost of $1,955 for the fleet, per inspection cycle.

Inspecting the flexbeam area and lead leg shims and bushings (annual inspection) requires about 2 work-hours, for a cost per helicopter of $170 and a cost of $3,910 for the fleet, per inspection cycle.

Eddy current inspecting (1,000 hour TIS inspection) the upper hub requires about 2 work-hours, for a cost per helicopter of $170 and a cost of $3,910 for the fleet.

If required, replacing the upper hub requires about 11 work-hours, and required parts would cost about $15,998, for a cost per helicopter of $16,933.

If required, replacing a missing or damaged fillet seal requires about .5 work-hour, and required parts cost would be minimal, for a cost per helicopter of $43.

FMI: AD