Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
SW-11-31 R1
July 18, 2011
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) is to inform
owners and operators of rotorcraft equipped with Honeywell MK XXII
Enhanced Ground Proximity Warning System (EGPWS). There is an
airworthiness concern regarding operation of a rotorcraft with a MK
XXII EGPWS system installed that has not been updated to correct a
condition where there could be unannunciated loss of functions of that
system. At this time, this 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.
This revised SAIB provides more information on how to make the
recommended changes to address this airworthiness concern. All other
information remains the same.
Background
Honeywell’s MK XXII EGPWS system is designed to be used on rotorcraft
equipped with a radio altimeter. The radio altimeter valid signal is
one criteria used to determine the rotorcraft’s transition from
on-ground to in-flight. This transition must take place for the EGPWS
to enable the predictive warnings and cautions associated with the
“look-ahead” features of the EGPWS. In previous software versions,
prior to the release and installation of the software update described
in Honeywell Service Bulletins ATA Numbers 965-1590/1595-34-36 and
965-1595-34-22 (Honeywell publication numbers D201009000034 and
D201006000021, respectively), there exists scenarios where this
transition does not take place. In this operational state, the
predictive warnings and cautions of the “look ahead” features are not
activated and there is no annunciation of the degraded operational
condition to the pilot. The software version listed in the appropriate
Honeywell service bulletin corrects this issue, and is currently
available from Honeywell at no charge.
Recommendations
We strongly recommend owners and operators of rotorcraft equipped with
a Honeywell MK XXII EGPWS system contact Honeywell and the Supplemental
Type Certificate holder for their installation to arrange installation
and incorporation of the appropriate Application Software Version for
their system as described in Honeywell Service Bulletins referenced
above. Failure to do so could result in less than desired or expected
protection from inadvertent controlled flight into terrain or obstacles.