Why Are My Universal Avionics Units Rejecting GPS Almanac Data?

May 2019

As of 2:00 UTC, Friday, April 5, 2019, all Universal Avionics units with a GPS-1000 sensor and 10.3 SCN (Software Control Number) installed are experiencing rollover failure of RAIM predictions that prevent the use of GPS for any approach operation. This is a result of the GPS Week Number Rollover that occurred during that same time.

Universal Avionics issued SB (Service Bulletin) 1XXX.( )-34-3724 on March 4, 2019, to correct this issue. Compliance is achieved through the installation of SCN 10.4. Although this SB is optional, it is highly recommended because the unit will be unable to perform GPS approaches without it. This software modification can only be performed by a Universal Avionics Authorized Service Center.

SB -3724 is keeping the Duncan Aviation Avionics & Instruments shop very busy, with units arriving weekly. It is important to note that more than 90% of the incoming units we have received require new batteries. The existing batteries have not been meeting the minimum battery levels required to meet the final performance test.  

If you have any questions or would like to schedule your unit in for this service bulletin, please contact the Duncan Aviation Avionics & Instruments Customer Account Reps.

Dan Magnus Avionics Tech Rep Lincoln, NE (LNK)
+1 402.479.4217