Bell BH47 Pilot examiner reported a runway excursion of a single pilot C172 that lost control from a hard landing; resulted in the BH47 taking evasive action to avoid a collision.

Narrative

I was practicing in an Bell 47 helicopter with another flight instructor in preparation to provide the owner of the aircraft with a private pilot check ride. The purpose of the flight was to allow me to become familiar with the aircraft prior to conducting an examination scheduled for the following day. I am a helicopter examiner and was flying with an instructor that is a former examiner. We were conducting pattern work at ZZZ airport. There was no other traffic at the airport. Though the winds were favoring Runway XX; we were practicing approaches to the mowed grass area east of Runway Y. While hovering in the area; we heard an aircraft report on the radio that they were entering the pattern for ZZZ1. This seemed strange as ZZZ1 is on a different frequency and several miles to the south of ZZZ. The same voice then stated that they were entering the pattern for ZZZ. I told the CFI that was in the helicopter with me that I did not feel comfortable taking off because the airplane reporting inbound did not seem to know where she was. We advised on the CTAF frequency that we were conducting hover operations in the grass east of Runway Y. There was no response. It was then that I saw the Cessna 172 pass just north of Runway XX at approximate 500-700 feet. The Cessna pilot advised that she was entering the pattern for Runway Y. I thought this to be strange as the wind favored Runway XX and that was the longer runway. I advised my fellow CFI that I wanted to move away from the runway and remain on the ground as not to disturb the airflow for the obviously new pilot that was about to land. I hovered the helicopter to a point that was approximately 100 feet from the runway near the segmented circle for the wind sock. I positioned the aircraft facing south so that we could watch the airplane approach and land. As the pilot did not seem to have very good control of the aircraft on final approach; I stated that if she were to come toward us; I would lift off from the ground and proceed toward the trees just to our east. It then appeared that the pilot suddenly noticed the set of wires that cross approximate 400 feet prior to the runway. The aircraft pitched up suddenly; apparently to avoid the wire; then dropped to the runway in a very uncontrolled state. After the first bounce on the runway; the aircraft drifted out of control to the east and onto the grass. The airplane continued out of control directly toward our aircraft. We lifted off just before the airplane continued directly through where we had just been stationary on the ground and then continued down the grass; swerving to avoid a runway edge light as it re-entered the runway. We contacted the flight club that owns the aircraft to advise them of the possible unsafe pilot and potential aircraft damage from the hard landing.