NAV425EX-100 Units Affected

Aero-News learned Wednesday that Crossbow Technologies has released a Service Bulletin affecting NAV425EX-100 systems, part numbers 8360-0171-01 and 8350-0171-01.

The NAV425EX-100 is designed to provide correct attitude and heading information during all flight conditions. However, under specific GPS satellite conditions inaccurate GPS information can be generated within the NAV425EX-100 which may result in inaccurate data from the NAV425EX-100. Inaccurate bank and heading indications have been observed under such conditions. The condition can be detected by comparison to backup mechanical attitude indicators, magnetic compass or the outside horizon if flying VFR.

The GPS manufacturer has issued a software update to the GPS firmware inside the NAV425EX-100 that eliminates erroneous data during specific satellite configurations and flight profiles. The GPS settings have also been further tightened by Crossbow to improve the quality of data that is utilized for navigation by the NAV425EX-100 during normal operation.

The NAV425EX-100 firmware has also been updated to provide additional features to the user, including BIT status changes that will provide additional levels of detail in regards to the operation of the NAV425EX-100. Finally, the NAV425EX-100 firmware has also been updated to increase heading slaving to the magnetometer, effectively improving heading response to magnetic field changes.

The bulletin is mandatory for IFR flight operations utilizing the NAV425EX-100. It is voluntary for VFR flight operations. All versions of the NAV425EX-200 are covered under a separate bulletin, and are not affected by this latest issuance.

Crossbow Letter NAV425-06-07 describes the conditions, how to recognize the conditions, and procedures for continued safe operation.

FMI: www.xbow.com