Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Flight Crew Commercial; Flight Crew Instrument; Flight Crew Flight Instructor
Flight Crew Last 90 Days 139; Flight Crew Total 708; Flight Crew Type 101
Workload; Distraction
Conflict NMAC
Flight Crew Took Evasive Action
Procedure; Human Factors
Upon crossing over a well-known rejoin point northwest of the airport; we were instructed to enter a left downwind for Runway 35.  As we neared the pattern I heard a helicopter cleared for the option on Pad 6.  We entered the downwind for Runway 35; tracking southbound just east of Runway 36. There was additional traffic; a Cessna 206; inbound from the south; reporting about 5 miles out.  I did not hear or observe any other traffic in the SLN class D airspace at the time.Just as we completed our before landing checklist and reported on a midfield downwind; SLN Tower instructed us to 'Make short approach Runway 35; cleared to land; Runway 35'.  We complied with the instructions and turned base abeam the approach lights for Runway 35.  At approximately 500ft AGL on the left base for 35 (short approach) the helicopter passed from right to left; crossing our path 50-100 feet directly below us.  I instructed my student to add power; which he did; and we climbed slightly; then reduced power and continued the approach to a normal; full stop landing on Runway 35.  At no point from the time we called over the rejoin point to the time that we touched down on the pavement did SLN Tower issue a traffic advisory to us regarding the helicopter; nor did we request a short approach - it was issued to us unexpectedly and for no reason that we could determine. Immediately after the conflict I observed the helicopter slow to a stop on final approach for Pad 6 and hover in place; then slowly continue their approach. They never spoke on frequency.After exiting the runway and completing our after landing checklist; I informed ground control of the conflict with the helicopter and lack of an advisory; and the controller responded 'Roger; I'll let him know.' Nothing more was said regarding the conflict.My student was in the right seat and I was in the left; he desired right seat time in order to practice for his upcoming CFI training.  He was focused inside the airplane (looking to the left of the instrument panel); and I was looking to my left when the conflict occurred.  We both verbally announced clearing our turn to base; but did not clear the final for Pad 6 as we passed by it - I was coaching the student on his airspeed and power control during the short approach.  I could have avoided the conflict by more earnestly scanning he right side of the aircraft; and my student could have focused more outside the airplane.  Additionally; the helicopter could have also yielded; however it was also piloted by an instructor and student likely experiencing the same task load. Additionally; voices could be heard talking in the background during tower control transmissions.  The tower controller may have issued us the short approach to help aid in spacing with the other aircraft to the south; but seemed to forget that the helicopter was operating in the pattern for Pad 6.
Flight school instructor reported an NMAC with a helicopter in the pattern at SLN.