As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NEITHER GPS WOULD ACQUIRE POSITION. TROUBLESHOOTING REVEALED THAT THE NR 2 GPS ANTENNA WAS FAILED & RADIATING ON GPS FREQUENCY, CAUSING INTERFERENCE FOR NR 1 GPS. IT IS APPARENT THAT THIS ANTENNA FAILURE MODE IS NOT UNCOMMON. CONSIDERING THAT THE EFFECTED GPS UNITS ARE CERTIFIED AS SOLE MEANS OF NAVIGATION, A KNOWN PROBLEM OF THIS TYPE IS VERY CONCERNING. THE NR 2 GPS ANTENNA WAS REPLACED WITH NEW WITH NO ABNORMALITIES NOTED.