Small Aircraft; High Wing; 1 Eng; Fixed Gear
Flight Crew Instrument; Flight Crew Commercial
Flight Crew Last 90 Days 30; Flight Crew Total 5400; Flight Crew Type 4000
Communication Breakdown; Situational Awareness
Conflict NMAC; Ground Incursion Runway
General None Reported / Taken
Human Factors
Incident site is AUN.  Two aircraft in pattern making extensive position reports; speaking in a fast clipped manner. Three other aircraft approaching airport making short; to the point initial reports. I am on run up pad for [Runway] 25 monitoring radio report. Hear someone say 'base'. I continue with my pre-takeoff check. Checklist completed; I check for traffic on base and final (base leg is partially obscured by a hill) and runway traffic. None. I broadcast my intentions and taxi from run up pad to limit lines at taxi way/runway junction heading easterly to check for traffic on base or final. None. Pull out onto and line up on runway; check for aircraft; animals etc.; on runway. With a clear runway; I apply power and make a normal takeoff. Two thirds down and about 300 feet above the runway I start a left noise abatement turn and spot a helicopter perpendicular to the runway centerline exiting from the runway to the taxiway.I never saw the helicopter until then!
GA pilot reported an NMAC with a helicopter during initial climb from AUN airport. Pilot stated they checked for traffic before departing but did not see the helicopter.