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Recent Service Bulletins and Letters

Jun 18, 2018
By: Stacy Honda, Marketing Manager

Visit UniNet today to download any of our Service Bulletins (SB) or Service Letters (SL), including the recently released ones listed below, from the Tech Pubs tab.

SB/SL

Release Date

Title

SB3703

06/08/2018

ALERT - Erroneous Date/Expired Database/GPS-based Approach Operations Not Allowed

SB3706

06/08/2018

Procedures for Correcting Erroneous Date Expired Database Message in the Flight Management System

SB3705

06/08/2018

Field Procedures for Correcting Erroneous Date Expired Database Message in the Flight Management System

SL2885

05/16/2018

Data Transfer Unit (DTU) and Portable Date Transfer Unit (PDTU) Repair Service

SL2886

05/16/2018

Global Positioning System (GPS) GPS-950 and GPS-1200 Repair Service

Alert SB3703

On 3 June 2018, the GPS/GNSS sensor embedded in the UA Flight Management System (FMS) began exhibiting a UTC date error. Note: this issue does not affect WAAS/SBAS-FMS units with Software Control Number (SCN) 100X/110X.
There are two primary symptoms discernable to the crew:

  1. The UTC date field on the INIT page and/or on DATA Page 4/4 will be erroneous, not current.
  2. The FMS will generate a DATABASE EXPIRED message, even if the database is known to be current.

Secondary symptom of the erroneous UTC date is:

  1. GPS-based approaches cannot be executed due to the UTC date error. The error affects the RAIM prediction function. If an attempt is made to execute an approach using GPS, the FMS will generate a NO RAIM AT FAF message and NAV flags will be presented after passing the FAF.
  2. Depending upon aircraft integration and regional regulations, the following approach types may be usable: VOR, Localizer (LOC), Back Course (BC) and ILS. These approach types do not require a RAIM prediction and are therefore usable approach types.

The GPS UTC date does not affect the receiver ranging and positioning operations. The position solution and navigation function are unaffected and may be relied upon for enroute and terminal operations.

Corrective Action

Please refer to UA SB No. 3705, Field Procedures for Correcting Erroneous Date Expired Database Message in the Flight Management System, and SB No. 3706, Procedures for Correcting Erroneous Date Expired Database Message in the Flight Management System, for procedures to correct the UTC date error.

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