We were a party of 5 adults exploring canyons in Wollemi National Park.  The activity included abseiling in the canyons. In one canyon, Frank slipped and fell during an abseil.  He sustained multiple injuries, including broken jaw, cracked ribs and a broken sacrum. We checked for consciousness, placed him in recovery position and cleared his mouth of blood from broken jaw/teeth. He was in severe pain but conscious. We then immediately deployed our ACR ResQLink + PLB at a point close by where more sky was visible.  The green light displayed in 2 or 3 minutes, indicating our distress and location was known to emergency services.  After approximately 2 hours, a Police helicopter was heard overhead. We made visual contact with rescuers on board. The helicopter spent perhaps 20 minutes circling and surveying the extremely rugged and difficult terrain to find the best location for winching in a paramedic, deep inside a canyon. Eventually the paramedic dropped in with a ton of equipment in packs and a stretcher. Art and I escorted him to where Frank was lying with the others.  After doing preliminary checks and administering pain killers etc, we lifted Frank into the stretcher, strapped him in, and carried him through the canyon to the winch-out point.  The helicopter was contacted and soon returned, and Frank was winched to safety.  He is now stable and recovering in hospital.  By this time, darkness was approaching, so the rest of our party stayed overnight in the canyon and walked out safely the following morning.