Date: 201912
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operator: FBO
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Parked
Aircraft component: Communication Systems
Component problem: Failed
Reporter organization: FBO
Reporter qualification: Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial; Flight Crew Multiengine
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport

Narrative: Dual mission to ZZZ. From ZZZ1 to ZZZ; uneventful. When we did the crew swap I was teaching my student to setup something on the GPS. Someone then transmitted saying 'whoever is teaching their student how to setup the GPS; you're transmitting on the ZZZ frequency. I noticed that the 'TX' was on; on the comm1 section on the PFD. I switched to comm2 and had the same issue. I pushed all 4 PTT to try and 'unstick' the mics and that didn't work. I shut everything down and restarted the avionics to try and reboot the system and uploaded the databases which generally does a reboot of the system. Neither of those worked either.I called Dispatch to talk to a Maintenance person. However; it was very limited and those that were here; did not know what to do. I called a few friends to see if they have had similar issues to try and stop the problem. They had no idea either. So; I Googled it and looked at the maintenance manual for the G1000. I concluded that it was an internal issue that would have to be fixed at ZZZ1. So; I called back to talk to a lead. No leads were available for some time and I was forced to wait until they could find someone.When I finally got a hold of a lead; I gave him the 3 options that I came up with. #1- Leave the airplane in ZZZ and have another plane come get us. #2- I put a 'dead' frequency as my primary transmitting so I don't clog up the frequencies and monitor the important one on comm2 and just switch back and forth. #3- I takeoff and call Tower with my cell phone and use the Bluetooth in my headset to communicate with them. We decided on option 3 and he called the Tower to coordinate for me. He called me back about 5 minutes later and we discussed the plan. I was to take off and monitor all the important frequencies and call the tower when I was about to ZZZ2 and they would clear me. Solid plan and we both agreed it would be the best case. So; I took off and did a downwind departure off Runway XX.During our taxi and takeoff; I could hear all the UNICOM traffic and thought that everything was going great. As I turned to downwind; everything got quiet. I noticed I could still see an 'RX' on comm2; so my radio is still receiving but I cant hear it. I had the volume set at 90% with no luck. I continued to the SW practice area with zero comms. I made a radio call advising people in the area that I'm having radio problems and what I was planning on doing (my current location and that I'm taking a direct route back to ZZZ1). I attempted to call the Tower 4 times before finally reaching them. They cleared me for landing and I landed without further incident.




Synopsis: PA-28 flight instructor reported that a stuck mic resulted in a NORDO flight back to the departure airport.