TWO PA28 PLTS EXPERIENCE NMAC IN TRAFFIC PATTERN AT NON-TOWERED ARPT.

Narrative

AFTER ROTATION TO INITIAL CLB FOR CLOSED TFC AT ZZZ; RWY 1; HDG 011 DEGS; RADIO CALL ON CTAF 'ARCHER XWIND FOR RWY 1;' NO TFC IN SIGHT. ANNOUNCED INTENTIONS THEN TURNED XWIND FOR RWY 1; RADIO CALL ON CTAF; 'I HAVE CHEROKEE IN SIGHT; I AM BEHIND YOU.' TURNED DOWNWIND SLIGHTLY HIGH (900 FT MSL; TYPICAL TPA 850 FT MSL FOR FIXED-WING; 1000 FT MSL OPPOSITE SIDE FOR ROTORCRAFT); ARCHER TURNED DOWNWIND; RPTED ON RADIO TO HAVE LOST VISUAL CONTACT WITH MY ACFT. IMMEDIATELY INITIATED 45 DEG TURN TO DEPART THE PATTERN; ANNOUNCED INTENTIONS ON CTAF; RADIO CALL ON CTAF FROM A HELI IN THE PATTERN; 'ARCHER IS 100 FT IMMEDIATELY BELOW YOU.' RE-ENTERED PATTERN FROM 45 DEG DOWNWIND LEG. BOTH ACFT LANDED WITHOUT FURTHER EVENTS. CONTRIBUTING FACTORS: 1) TFC ENTERED ON EXTENDED XWIND; 2) TFC WAS NOT VISIBLE (NO LIGHTS SEEN); 3) TFC STATED THEY WERE FOLLOWING AND THEN MADE AN EARLY DOWNWIND TURN UNDERNEATH LEADING ACFT. PREVENTING RECURRENCE: 1) USE STANDARD 45 DEG DOWNWIND ENTRY; 2) USE AVAILABLE FORWARD-FACING LIGHTS WHILE IN THE PATTERN; 3) IF AN ACFT CONFIRMS THAT THEY ARE FOLLOWING ANOTHER ACFT IN THE PATTERN THEY SHOULD ACTUALLY FOLLOW INSTEAD OF CUTTING OFF THE LEADING TFC.