WAAS Upgrade Not Yet Working Well With PFDs
On Friday, Avidyne issued a mandatory service bulletin detailing
information on known incompatibilities between Garmin 400W/500W
series navigators and Avidyne Primary Flight Displays. It includes
mandatory operational limitations for aircraft with certain
combinations of equipment and recommends against new or updated
installations in affected configurations.
Avidyne tells ANN the bulletin communicates important safety
information concerning aircraft equipped with Avidyne EXP5000
Primary Flight Displays ("Avidyne PFDs") and Garmin
400W/500W-series navigators with WAAS ("Garmin WAAS
navigators").
As Aero-News reported, Garmin
recently introduced upgrades to its 400/500-series GPS navigators
to incorporate support for the Wide Area Augmentation System
(WAAS). The new models are designated the 400W/500W-series, and is
available both as new production and as upgrades to previously
purchased 400/500-series navigators.
Avidyne states many Garmin 400/500-series navigators are
installed in airplanes equipped with Avidyne PFDs. When operators
of those planes -- hoping to take advantage of the improved
accuracy and added features of WAAS -- install the upgrade,
however, it has caused serious incompatibility issues between the
Garmin WAAS navigators, and the Avidyne PFDs.
The Garmin WAAS navigators make use of extended precision in
transmitting course deviation data while on GPS approaches -- an
extended precision that was not anticipated in the development of
the Avidyne PFD, according to the company. As a result, the PFD may
erroneously display a centered HDI/CDI needle on final approach...
when an off-center indication is appropriate.
As of this date, there is no information in either
Garmin’s installation data or Avidyne's installation data to
indicate compatibility of this equipment, nor is there any approval
basis in an STC held by Garmin or Avidyne or any TC held by any
airplane manufacturer. Nevertheless, it has come to Avidyne's
attention that upgrades of existing installations from
400/500-series navigators to 400W/500W-series navigators in
airplanes equipped with Avidyne PFDs may have been performed via
some form of field approval.
Avidyne says it is preparing a modification to the PFD that will
correct the incompatibility. Until a compatible configuration of
Avidyne PFD and Garmin WAAS navigators is installed, however, no
GPS approaches of any type may be flown in affected aircraft. Only
LOC, ILS and VOR approaches (by means of VOR, not by means of GPS)
may be flown.
Avidyne also strongly recommends against upgrades of Garmin
400/500-series navigators to 400W/500W-series in affected airplanes
until a compatible Avidyne PFD software version is available and
installed.
Note: Avidyne IS hard at work on a significant
upgrade to the software that powers the Entegra system,
which will incorporate the necessary WAAS support.
Availability is expected in 3Q/07. Additional info is now available
at www.avidyne.com/products/release7.shtm.
FMI: www.avidyne.com, call
888-723-7592 for more information