A technical loss of separation occurred when a Tower Controller allowed a landing on a runway with a stationary ground helicopter operation at the other end of the same runway.

Narrative

I was working Local Control 1 and Local Control 2 combined. There was some construction on the north end of the airport but it really did not play into this event. I had a small helicopter doing ground practice work on the northwest end of Runway 16/34 restricted northwest of Taxiway Hotel. This is a normal operation at the airport and this portion of Runway 16/34 belongs to the Local Controller even when this runway is not active to allow for helicopter operations northwest of Taxiway Hotel. The helicopter had been working for about and hour and had departed to the northwest and returned to continue ground practice during this period. I had also had multiple helicopters arrive and depart the helipad which is off the northwest end of Runway 16. They all departed the area or had proceeded to the ramp. An SR22 was inbound to the airport on a right downwind to the other runway. The wind started to increase from the northwest up to 10-15 KTS so I offered the SR22 Runway 34; totally forgetting about the helicopter still working in the area of the numbers of Runway 16 sitting on the ground. The SR22 accepted the offer of Runway 34 and I did the appropriate coordination with the Ground Controller to make Runway 34 Local's control. I then cleared the SR22 to land Runway 34 and scanned the runway; but did not observe the helicopter; which was sitting on the runway and blended in with the white runway stripping. Nor did the hand written strip; I had written for the helicopter seem to jog my awareness. In my mind I guess I thought the helicopter had gone to the ramp even though I knew he in fact had not. When the SR22 was rolling out and I was instructing the aircraft where to exit the runway; I remembered and observed the helicopter sitting on the northwest end of Runway 16/34. I don't think the pilot of the SR22; or the pilot of the helicopter ever saw each other; as neither said a word. Nor do I believe anyone else in the Tower ever knew the error had occurred. Neither the FLM nor the Ground Controller said a word. I just made a plain foolish error. I was even the one that suggested the SR22 change its runway to Runway 34. All the visual aids were used; all the procedures were followed I just made a mistake. Another person listening to me may have prevented this error but traffic was very light. I just made a mistake.