Pilot reported communications problems led to the helicopter being flown on a ferry flight back to base without proper documentation and procedures. The pilot removed the aircraft from service after arrival back at home base.

Narrative

At approximately XA:00 on Date we landed on scene. Patient was loaded on aircraft and crew member on left side entered aircraft and attempted to shut sliding door. After a couple attempts to latch door the sliding mechanism fell off rail. Patient was off loaded back onto rescue and ground transported to hospital. Crew was given a ride back to base while I stayed with aircraft. I notified mechanic on call of situation to start heading our way.I called AIRCOM; [Dispatch]; and Military Control (M/C) and let them know what was going on. I do not remember in which order I made these 4 phone calls. The aircraft was then taken out of service for maintenance. I did not make a write up at this time. The mechanic arrived at the aircraft and started to put the door back on its track. While the mechanic was finishing securing the door I contacted Military Control again. I had to explain a couple times that the mechanic was just securing the door so we could get the aircraft back to base and not put it back into revenue service at this time. I was confused because Military Control said this was not possible without a ferry permit the first time I explained the situation.Once I explained it again I was under the impression they were going to put the aircraft back into service just to get it home then we would take it back out of service for any follow up maintenance that had to be performed. I then called AIRCOM to let them know what we were trying to do. They mentioned I would fly it back as a maintenance flight so that is what I entered into complete flight. I mistakenly assumed while all of this was going on the Mechanic had taken care of the log book because I was told I was good to go after I hung up with AIRCOM. I did not double check the logbook.At this point I had been up all night and was very tired and it was shift change. I flew the aircraft back to base with no problems. I called Military Control again to take the aircraft back out of service. At this point the person on the phone seemed upset and told me I should not have flown back without the mechanic sending in paperwork. I was very confused because he could not have done this from the scene and I thought I had heard differently. I hung up with Military Control and did crew change with oncoming pilot and went home.