Textron Aviation has released a technical information notification:
Collins Pro Line 21 or Pro Line Fusion equipped airplanes with GPS-4000S 822-2189-100 could experience a loss of Global Positioning System (GPS) during the week starting June 11, 2023. In the interest of scheduling, Textron Aviation recommends pursuing an upgrade to the 822-2189-101 GPS as soon as practical. These units were installed via STC on Premier, Hawker, 525, 525A, 525B, and 560 series airplanes, in addition to STC and production deliveries of 560XL, King Air, and CJ4.
STC installations can be upgraded to 822-2189-101 via Collins service bulletin GPS-4X00( )-34-510. Production installations can comply with the following service letters, which have been revised to align with airworthiness directive (AD) 2021-08-07. As of October 2021, these service documents are categorized as Mandatory Compliance for the serial numbers (shown by model) listed below :
560XL (refer to service document SL560XL-34-27):
560XL-6001 thru -6289
CJ4 (refer to service document SL525C-34-07):
525C-0001 thru -0327
King Air (refer to service document MTL-34-01):
King Air C90GTi Series, LJ-2151 thru LJ-2173
Super King Air B200GT, BY-324 thru BY-379
Super King Air B300, FL-1140 thru FL-1222
Super King Air B300/B300C, FM-76 thru FM-85