According to Strocks, "Vibration typically is not a problem unless there is FOD damage or if the fan assembly has been removed and reinstalled for some reason."
Strocks says the fan is easily balanced with a dynamic balancer of your choosing. You simply use the balancer to determine the amount and location of imbalance, and then each blade has its own balancing stud to which weight can be added or removed in order to achieve balance.
"Once the fan is balanced, it typically stays balanced so well there is no need for a periodic balance as is required on the tail rotor. Balance is on condition only," says Strocks.
"The blades themselves are a thermoplastic and are very durable. It is possible, but rare, to damage the blades, as the intake is located at the top of the fuselage."
However, Foreign Object Damage is possible. "One set of blades that we received recently, was damaged by a mechanic who left a shop rag in the area. The rag was ingested and it tore up the blades considerably. Tip clearance should be maintained within limits. This is done with a titanium felt tip seal which is cut to size on installation of the fan assembly to produce a predetermined clearance."
Strocks adds, "In terms of the remainder of the NOTAR system there really isn't much maintenance to perform. The composite tail boom is relatively maintenance free, and the vertical stabilators are very simplistic in their operation."
The remainder of the maintenance technician's responsibility is tracking the life limit of the major components. A few of the components have finite life limits, which means you remove and discard components after a specific period of time.
"By the way," explains Strocks, "the warranty period on all NOTAR components is 3,000 hours, which is very high for the industry. Based on our experience, the only item that even comes close to requiring maintenance before this time might be the fan tip seal. And even this would only be required if the operator is running the helicopter in a harsh environment where sand, and what not, will cause excessive erosion of the fan tip seal. Corrosion has also been a problem in coastal environments."
"All in all, it's a very simple system to maintain," says Strocks.
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