Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 13; Flight Crew Total 279; Flight Crew Type 275
Confusion; Situational Awareness
Conflict NMAC
Flight Crew Took Evasive Action
Procedure; Human Factors; Airport
After making a left base at ZZZ call over CTAF; the R66 stated over communications they were '3 miles NE of the field'; after hearing this we asked if they could see us. They replied they saw us right over them. After hearing this we decided to take evasive action and discontinue our approach and continue straight west of the field; away from the other aircraft. We did not see the aircraft until they were short final of the field. They did not adhere to standard taxi pattern procedures and came in right underneath us on our base leg. The pilot of the Robinson did not state they saw us and were number 2 for the runway or anything so we just decided to get out of their way and try again later after they were no longer a safety factor for us.
C172 instructor pilot conducting training at a non-towered airport reported an NMAC with a helicopter which was not flying according to standard patterns.