I sent one to Airtime for a repair, and they did not provide a MRA. I have someone local do repairs like this now. He has the third one this year to weld. All three have had the same issue, a small crack just inside the factory weld for the internal baffles in the muffler. I think there is a flange that is causing stress. All were inside the cabin heat muff. Make sure you have a good carbon monoxide detector, especially when you are using the heater.