Narrative:

I departed with a student and I went to robertson airport (4b8) to demonstrate an autorotation. 5 mi out I started making my calls to 4b8 CTAF; but when requesting traffic advisory I got no response so since the wind was coming from the north I decided to use runway 2. Because I was approaching the pattern from the southeast I joined a right base for runway 2 at 800 ft AGL. The whole time I was making my radio calls stating my position and intentions. When I was on my right base I could see a small airplane on what would be a left downwind for runway 2. The small airplane was not making any radio calls; but at this point aircraft separation was not an issue and I continued to final. On final I entered a normal straight-in autorotation which was to be terminated in 3-5 ft hover on the runway. As I was coming to the end of the maneuver; I started to initiate my flare and just as I do I can see the small airplane roll out from right underneath me. The aircraft clearance was uncomfortably small and I right away had to make an early power recovery and sidestep to avoid the airplane.

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Original NASA ASRS Text

Title: HELICOPTER PILOT PRACTICING AN AUTO ROTATION AT 4B8 HAS A SMALL ACFT PASS BENEATH HIM AS HE IS ENTERING THE FLARE AT 15 FEET.

Narrative: I DEPARTED WITH A STUDENT AND I WENT TO ROBERTSON ARPT (4B8) TO DEMONSTRATE AN AUTOROTATION. 5 MI OUT I STARTED MAKING MY CALLS TO 4B8 CTAF; BUT WHEN REQUESTING TFC ADVISORY I GOT NO RESPONSE SO SINCE THE WIND WAS COMING FROM THE N I DECIDED TO USE RWY 2. BECAUSE I WAS APCHING THE PATTERN FROM THE SE I JOINED A R BASE FOR RWY 2 AT 800 FT AGL. THE WHOLE TIME I WAS MAKING MY RADIO CALLS STATING MY POS AND INTENTIONS. WHEN I WAS ON MY R BASE I COULD SEE A SMALL AIRPLANE ON WHAT WOULD BE A L DOWNWIND FOR RWY 2. THE SMALL AIRPLANE WAS NOT MAKING ANY RADIO CALLS; BUT AT THIS POINT ACFT SEPARATION WAS NOT AN ISSUE AND I CONTINUED TO FINAL. ON FINAL I ENTERED A NORMAL STRAIGHT-IN AUTOROTATION WHICH WAS TO BE TERMINATED IN 3-5 FT HOVER ON THE RWY. AS I WAS COMING TO THE END OF THE MANEUVER; I STARTED TO INITIATE MY FLARE AND JUST AS I DO I CAN SEE THE SMALL AIRPLANE ROLL OUT FROM R UNDERNEATH ME. THE ACFT CLRNC WAS UNCOMFORTABLY SMALL AND I RIGHT AWAY HAD TO MAKE AN EARLY PWR RECOVERY AND SIDESTEP TO AVOID THE AIRPLANE.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.