As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRIOR TO TAKE-OFF, RADIO #4 WAS FOUND TO BE INOP. STAYS ON AIRFIELD ATIS REGARDLESS OF SELECTED CHANNEL. SELECTING OTHER CHANNELS RESULTED IN OVERPOWERING SQUELCH/STATIC SOUND. NO SIDE TONE WHEN ATTEMPTING TO TRANSMIT. AFTER SUBBING KNOWN GOOD C-5000 RADIO, THE STATIC WENT AWAY AND SIDE TONE COULD BE HEARD WHEN TRANSMITTING. REMOVED AND REPLACED C-5000 CONTROL HEAD IAW 145 MMS-015. MOC OK.