AD FAA-2012-0758

We are adopting a new airworthiness directive (AD) for certain aircraft equipped with Honeywell International, Inc. Model KGS200 Mercury\2\ wide area augmentation system (WAAS) global navigation satellite sensor units (GNSSU). This AD requires you cease all localizer performance (LP), localizer performance with vertical guidance (LPV), and satellite based augmentation system (SBAS) lateral navigation/vertical navigation (LNAV/VNAV) approaches until a software problem is corrected. This AD was prompted by a report and follow-up investigation of a software problem that occurred during flight test trials of SBAS-capable aircraft using a similar Honeywell global positioning system (GPS) sensor and the same software as the Model KGS200 Mercury\2\ GNSSU. A software problem occurred that could result in misleading information during LP, LPV, or SBAS LNAV/VNAV approaches. We are issuing this AD to correct the unsafe condition on these products.