The bulletin
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FAA Aviation Safety
SPECIAL AIRWORTHINESS
INFORMATION BULLETIN SAIB: SW-11-31 SUBJ: Honeywell MK XXII Enhanced Ground Proximity Warning System Date: May 11, 2011 This is information only. Recommendations aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin is to inform owners and operators of an airworthiness concern on rotorcraft equipped with a Honeywell MK XXII Enhanced Ground Proximity Warning System (EGPWS). The concern regards operating rotorcraft with a MK XXII EGPWS 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.
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 Bulletin ATA Number 965-1595-34-22 (Honeywell publication number D201006000021), scenarios exist 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 above 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 arrange to install and incorporate the part number 965-1595- 028 Application Software Version as described in the Honeywell Service Bulletin referenced above.
Failure to do so could result in less than desired or expected protection from inadvertent controlled flight into terrain or obstacles.
For Further Information Contact
George Schwab, Aerospace Engineer, FAA Rotorcraft Directorate, FAA Rotorcraft Standards Staff, Safety Management Group, 2601 Meacham Blvd., Ft. Worth, TX 76137; phone: (817) 222-5114; fax:
(817) 222-5961; e-mail: george.schwab@faa.gov.