4 MAINTENANCE PRACTICES
4.1 GENERAL
Normal maintenance activities performed on the EGPWS should follow standard industry maintenance practices. System maintenance practices may include; updating a database, downloading flight history data, and programming or reprogramming the MK VI or MK VIII Configuration Module. These are addressed in the following sections.
4.2 DATABASE UPDATE
The Enhanced Ground Proximity Warning System (EGPWS) uses Terrain, Obstacle, Runway, and Envelope Modulation databases to provide enhanced functions. These are periodically updated, as new data becomes available. The Terrain, Obstacle, and Runway databases are typically combined and loaded into the EGPWS as one database, however it is possible that individual database updates could be provided. The procedure for loading a database update is the same in all cases and this section will address them as a database update generically.
For each new (updated) database, Honeywell will provide notification of the new database via a Service Bulletin (SB). The SB will be sent to all registered EGPWS customers, or they will be available for download off the Internet at www.egpws.com. The SB will contain a description of the changes in the database, as compared to the previous database, so that each customer can determine the applicability of the database update to their operations. For example, a Terrain database update involving only terrain in South America will be of no value to a domestic U.S. airline. Thus, the domestic U.S. airline would not need the database update. The SB will also contain instructions on how to obtain and install the new Terrain Database and any required modifications. Database updates are coordinated with the FAA prior to SB release via a Honeywell “minor mod” notification process.
EGPWS databases are not identified on the EGPWC as a part of the unit part number. For the MK VI and MK VIII a separate label is placed on the unit front panel identifying the installed Terrain database number and for the MK VI the database region (see section 2.2.10.1). Otherwise, the installed databases can be determined in the Level 3 Self-Test (see Fault Isolation section) which should always be used to confirm the current database version.
4.2.1 DATABASE UPDATE FREQUENCY
Honeywell is continually striving to improve the EGPWS databases. New terrain, obstacle, or runway data is obtained by many different means, evaluated and verified, before it is processed into an EGPWS database. When sufficient or significant new data is available, Honeywell will release a database update.
Honeywell is committed to investigating reported nuisance alerts. When nuisance alerts result from database problems (accuracy, resolution), Honeywell will make corrections to the database. Nuisance alerts can also result in changes to the Envelope Modulation database, although this tends to be less frequently updated.
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