NetJets Aviation, Inc.

The subject of this Airworthiness Directive instructs operators of Cessna Model 560, 560XL as applicable to NetJets Aviation, Inc. (NJA) to perform an initial inspection of the brushes for AC compressor motor within 30 days or 10 flight hours. Thereafter these same brushers must be replaced on or before they reach 500 hours’ AC compressor motor time in service.  NetJets operates 29 aircraft affected by this AD, averaging 1,800 flight hours per month, 62 flight hours per aircraft. The 30 day or 10 flight hours inspection will place an un-due burden on the carrier and may force NetJets to either deactivate the system using our Minimum Equipment List or ground aircraft until such time as maintenance personnel and materials can be allocated for each aircraft. We would like to propose 90 days, 60 hours whichever comes first for parts (g) and (h) of AD 2012-1001. This would allow time to schedule maintenance personnel and material to support each aircraft without compromising safety.  NetJets is currently inspecting the AC compressor motor brushes every 1200 flight hours as part of our scheduled inspection program. In the past, NJA has found the hour meter to be an un-reliable source of reporting hour usage. The location of the AC unit within the aircraft makes the numbers on the meter hard to read at times and open to interpretation. We would like to propose that language in AD allow the recurring 500 hour AC compressor motor brush replacement be included in a scheduled inspection based on the Cessna 560 chapter 5 inspection programs. This would allow a more robust, systematic approach to scheduling brush replacement. Sincerely