Helicopter pilot reported that during landing his down wash caused an unattended small aircraft to rotate 180 degrees.

Narrative

I was returning from a flight and cleared to land on Taxiway Foxtrot abeam the air carrier ramp. We had been staging operations from the ramp since the prior day. The ramp area was restricted due to construction (resurfacing of the ramp) west of the landing area. The intersection of Foxtrot and the ramp is also the run up area for Runway 25.The ramp had been quite quiet the day before and had started to fill up with aircraft due to the approaching weekend. I flew my approach to the taxiway and as I was finishing my approach I observed an aircraft taxiing towards me from the ramp which was from the direction of my landing area. Although I assume I had the right of way being a landing aircraft; I offset over the construction area to give way to the approaching aircraft. The run up area had aircraft on it making it not an ideal area for me to land and wait for the aircraft to pass. I brought the helicopter up to 50-75 feet to minimize dust by diffusing the down wash and waited over the construction area for the aircraft to pass. The taxiing aircraft stopped to copy his IFR clearance. I heard this over the radio and recognized the N number on the aircraft. I waited in a hover until the aircraft taxied past our staging area. I then proceeded towards our landing area. While maintaining my altitude; I attempted to pass between two aircraft and landed at our staging area. I thought I had enough vertical and horizontal separation from the parked aircraft but my down wash caused the aircraft to rotate heading approximately 180 degrees. The parked aircraft had been brought out during our flight and was placed abeam our landing area during our absence. To my knowledge after the event; I don't think it had any chocks; tie downs or wheel locks applied. It had a canopy cover in place. We spoke with the owner regarding the incident. Although upset with the events; he did not mention any damage and flew the aircraft later that day. I also asked the FBO crew to move us to the end of the ramp and keep parked aircraft from the vicinity of our staging area. A consequence of the event is that the aircraft was moved by my down wash and will be inspected by a factory approved maintenance facility. Future corrections: 1. A chain of events and decisions I made placed me into a situation where I had to maneuver too close to aircraft on the ground. I should have aborted the approach and flown a pattern to let the congestion on the ramp subside or set down and wait somewhere. 2. In the future; I will be more cognizant of my down wash and keep more distance from parked fixed wing aircraft; especially composite aircraft due to their light weight and aerodynamic airfoils.