Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
CE-10-22
March 26, 2010
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin advises you of an
airworthiness concern regarding all modification levels of Honeywell
GNS Series Navigation Systems: GNS_XLS PRNAV, part number (P/N)
17960-0103-XXX; GNS_XLS Enhanced PRNAV, P/N 17960-0204-XXX; and GNS_XL
PRNAV, P/N 18355-0102-0XXX.
The FAA has completed a full review of this issue. At this time, the
airworthiness concern is not an unsafe condition that would warrant
airworthiness directive (AD) action under Title 14 of the Code of
Federal Aviation Regulations (14 CFR) part 39.
Background
Honeywell has recently discovered a software anomaly in their GNS
Navigation Systems. This anomaly may affect the area navigation (RNAV)
procedures, which contain RF (Radius-to-a-Fix) legs. If an RNAV
procedure containing RF legs is loaded into the flight plan with the
navigation system being used to fly the full procedure, the GNS system
could fail to capture and fly the RF leg curved path and continue past
the waypoint on an undetermined track line. It should be noted that the
GNS PRNAV systems are not approved for RNAV Required Navigation
Performance (RNP) procedures. Honeywell Service Information Letter
(Publication Number D201003000024) has been issued.
Recommendations
After reviewing the above data, we recommend that you adhere to the following:
Do not load any approach or departure procedure listed in Table 3 of the above-referenced Service Information Letter.
Do not load any approach or
departure procedure listed as Special Aircraft & Aircrew
Authorization Required or Special Authorization Required printed on the
aeronautical chart.
Do not load any approach or departure procedure requiring RF capability.
Refer to the above-referenced Service Information Letter for additional guidance.
The Honeywell website also provides information on this subject and can be accessed at:
https://portal.honeywell.com/wps/portal/aero