A R44 Pilot reported an off airport landing after the low fuel light illuminated. Preflight issues distracted him and multiple quick turn around tour flights caused additional distractions away from fuel concern.

Narrative

I was flying a series of 0.5-0.6 hour tours and on the fourth (and last) tour the low fuel light illuminated approximately eight miles out from the airport. I had already contacted the tour inbound so radioed to them that I was setting down due to low fuel and found a flat place and set down to call for fuel. Customers were being loaded and unloaded without engine shutdown in order to save time and enable us to complete the tours within their time and budgetary constraints; and tours were taking longer than anticipated with some customers asking for longer time around the city. As the last group was being loaded I should have done a more complete assessment of fuel quantity and reserves and shut down to obtain more fuel. Decisions/indecisions and risk factors: I overemphasized weight considerations; not filling the tanks completely before the tour group arrival in case the passengers turned out to be heavy (they were not). Extensive experience in the R22; for which 5 gallons is an adequate fuel reserve; and less cross country/long flight experience in the R44; for which that reserve is inadequate; made me tend toward an insufficient estimate of what I needed. The wish to keep the tours moving along and save my customers time and money made me rush both moving forward with the first tour (when I could have stopped to fill the tanks on realizing that we were not weight limited); and also made me reluctant to stop in the middle of the series of tours. When loading the last tour I did not have sufficient fuel to complete the tour. Unexpected tasks in the office that morning (filling in for another instructor on an instructional flight and clerical duties) filled up much of the two hours of preparation time I had allotted myself to prepare for the flight; again rushing through the preflight phase made me more likely to miss the error I had made in fuel calculation. Help from other instructors (because I was busy) involved fueling up the helicopter for me; removing me somewhat from concentrating on that flight and what was required for it.