Narrative:

As we prepared to take off from runway 34 at ZZZ we observed the medical helicopter transition from southwest to northeast at what appeared to be traffic pattern altitude; within 1 mi of the airport. This is not unusual; because they frequently travel between ZZZ2 and ZZZ3. However; there was no communication from the helicopter as it made its transition to the northeast. Having seen this; we proceeded to announce our intentions on CTAF. We taxied to runway 34 and departed. On upwind approximately 800-900 ft MSL; we observed the helicopter at our altitude crossing our flight path from right to left approximately 1000 ft in front of us. The helicopter had been previously out of sight due to surrounding terrain during the climb out. We were forced to execute a 90 degree turn to the left to avoid a collision course with the helicopter. The helicopter then proceeded in a westerly direction and descended into a field to meet local emergency personnel. At no time during the entire event did the helicopter make communications on ZZZ CTAF. It seemed as if no regard were given for the proximity of an airport. Shortly after the incident; we contacted another aircraft on the CTAF to inform them of the helicopter's presence. That aircraft acknowledged our transmission; leading me to believe our transmitter/receiver was functioning properly.

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Original NASA ASRS Text

Title: C172 PLT ON DEP FROM NON TWRED ARPT EXPERIENCED A CONFLICT WITH A NORDO MEDICAL HELI.

Narrative: AS WE PREPARED TO TAKE OFF FROM RWY 34 AT ZZZ WE OBSERVED THE MEDICAL HELI TRANSITION FROM SW TO NE AT WHAT APPEARED TO BE TFC PATTERN ALT; WITHIN 1 MI OF THE ARPT. THIS IS NOT UNUSUAL; BECAUSE THEY FREQUENTLY TRAVEL BTWN ZZZ2 AND ZZZ3. HOWEVER; THERE WAS NO COM FROM THE HELI AS IT MADE ITS TRANSITION TO THE NE. HAVING SEEN THIS; WE PROCEEDED TO ANNOUNCE OUR INTENTIONS ON CTAF. WE TAXIED TO RWY 34 AND DEPARTED. ON UPWIND APPROX 800-900 FT MSL; WE OBSERVED THE HELI AT OUR ALT XING OUR FLT PATH FROM R TO L APPROX 1000 FT IN FRONT OF US. THE HELI HAD BEEN PREVIOUSLY OUT OF SIGHT DUE TO SURROUNDING TERRAIN DURING THE CLBOUT. WE WERE FORCED TO EXECUTE A 90 DEG TURN TO THE L TO AVOID A COLLISION COURSE WITH THE HELI. THE HELI THEN PROCEEDED IN A WESTERLY DIRECTION AND DSNDED INTO A FIELD TO MEET LCL EMER PERSONNEL. AT NO TIME DURING THE ENTIRE EVENT DID THE HELI MAKE COMS ON ZZZ CTAF. IT SEEMED AS IF NO REGARD WERE GIVEN FOR THE PROX OF AN ARPT. SHORTLY AFTER THE INCIDENT; WE CONTACTED ANOTHER ACFT ON THE CTAF TO INFORM THEM OF THE HELI'S PRESENCE. THAT ACFT ACKNOWLEDGED OUR XMISSION; LEADING ME TO BELIEVE OUR XMITTER/RECEIVER WAS FUNCTIONING PROPERLY.

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.