Narrative:

En route from xyz to ZZZ for patient pickup. My aircraft encountered a 1/10 - 2/10 scattered layer of clouds at about 1800 MSL (at 1000 AGL). While climbing to continue above scattered layer, 2500 ft MSL we experienced a mechanical problem (#1) trans oil pressure went to '0'. We aborted flight and were descending back to land at abc. As we passed between the clouds at 18-1900 MSL (coverage about 1/10 at this point) suddenly a fixed wing aircraft, possibly an aircraft white in color, appeared out of the small cloud to our right, about 300-400 ft away heading straight toward our side. I reduced power and immediately placed the helicopter in a dive passing just ahead and below the oncoming fixed wing. Precautionary landing was accomplished at abc without further incident. While aircraft was being repaired, the aircraft was seen again slowly flying around the abc area going in and out of clouds. This area is just outside the abc's arsa normal service area. I was never able to get a tail number nor determine which direction the other aircraft finally went. My descent into abc was VFR at all times, (we had the landing zone in sight, when near miss occurred). Callback conversation with reporter revealed the following information. No additional comments during EMS structured callback.

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Original NASA ASRS Text

Title: EMS SMT ACFT FLC HAD NMAC WITH SMA SEL BENEATH AN ARSA AIRSPACE.

Narrative: ENRTE FROM XYZ TO ZZZ FOR PATIENT PICKUP. MY ACFT ENCOUNTERED A 1/10 - 2/10 SCATTERED LAYER OF CLOUDS AT ABOUT 1800 MSL (AT 1000 AGL). WHILE CLBING TO CONTINUE ABOVE SCATTERED LAYER, 2500 FT MSL WE EXPERIENCED A MECHANICAL PROBLEM (#1) TRANS OIL PRESSURE WENT TO '0'. WE ABORTED FLT AND WERE DSNDING BACK TO LAND AT ABC. AS WE PASSED BTWN THE CLOUDS AT 18-1900 MSL (COVERAGE ABOUT 1/10 AT THIS POINT) SUDDENLY A FIXED WING ACFT, POSSIBLY AN ACFT WHITE IN COLOR, APPEARED OUT OF THE SMALL CLOUD TO OUR R, ABOUT 300-400 FT AWAY HDG STRAIGHT TOWARD OUR SIDE. I REDUCED PWR AND IMMEDIATELY PLACED THE HELI IN A DIVE PASSING JUST AHEAD AND BELOW THE ONCOMING FIXED WING. PRECAUTIONARY LNDG WAS ACCOMPLISHED AT ABC WITHOUT FURTHER INCIDENT. WHILE ACFT WAS BEING REPAIRED, THE ACFT WAS SEEN AGAIN SLOWLY FLYING AROUND THE ABC AREA GOING IN AND OUT OF CLOUDS. THIS AREA IS JUST OUTSIDE THE ABC'S ARSA NORMAL SVC AREA. I WAS NEVER ABLE TO GET A TAIL NUMBER NOR DETERMINE WHICH DIRECTION THE OTHER ACFT FINALLY WENT. MY DSCNT INTO ABC WAS VFR AT ALL TIMES, (WE HAD THE LNDG ZONE IN SIGHT, WHEN NEAR MISS OCCURRED). CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. NO ADDITIONAL COMMENTS DURING EMS STRUCTURED CALLBACK.

Data retrieved from NASA's ASRS site as of July 2007 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.