Narrative:

I am a flight instructor and was to fly with a gentleman who stated to me that he had flown 70 different models of aircraft previously and had approximately 180 flight hours. The aircraft we were to fly has rudder pedals on both sides but only has brakes on the left side. I mentioned to him before the flight that I have no brakes and asked him how comfortable he is with taxiing. He stated he was fine and he had previously flown a similar model aircraft made by the same manufacturer with no problems. After engine start; I asked him to check his brakes as we were pulling out of the tie down spot and he did successfully. As we were taxiing he asked to practice using the brakes again and while we were still on the ramp; he used them to bring the aircraft to a complete stop. I was satisfied that he knew how to use them and we resumed taxiing without any issue. As we were nearing the runway; I told him to pull into the runup area. As we did; I asked him to slow down so that we could turn around and face into the wind. We did not slow down. I exclaimed to step on the brakes! He said he was on the brakes and they were not working. I realized we were nearing the edge of the runup area and were not going to stop. I promptly pulled the mixture control to idle which shut down the engine. I used my rudder pedals to steer us between the taxiway lights so that we would not hit any. We exited the taxiway/runup area and came to rest about 5-10 feet into the grass. Thankfully; there were no other aircraft in the runup area at that time and the grass area was flat. There was no damage to us the occupants; the aircraft; or the taxiway lights. After we came to rest; I informed ground control that we had exited the taxiway into the grass and they sent help to tow us back to the ramp. After returning to the ramp; myself and a mechanic inspected the brakes and found that they were working properly. Upon debrief with my student; we discovered that there is a 'ledge' pretty high above the rudder pedals which he mistook for the brakes. I also noticed that the pedals themselves are slightly smaller than most other aircraft. This most likely also hindered his attempt at finding the brakes. I am thankful that the outcome was not worse. This was a very humbling event and I will use it as a big learning experience which I will not forget for the rest of my career. I will also be much more diligent while taxiing in case an actual brake failure does ever occur.

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Original NASA ASRS Text

Title: M20 flight instructor reported exiting a taxiway into the grass when the student failed to properly apply the brakes in an aircraft that has only 1 set of brake pedals.

Narrative: I am a flight instructor and was to fly with a gentleman who stated to me that he had flown 70 different models of aircraft previously and had approximately 180 flight hours. The aircraft we were to fly has rudder pedals on both sides but only has brakes on the left side. I mentioned to him before the flight that I have no brakes and asked him how comfortable he is with taxiing. He stated he was fine and he had previously flown a similar model aircraft made by the same manufacturer with no problems. After engine start; I asked him to check his brakes as we were pulling out of the tie down spot and he did successfully. As we were taxiing he asked to practice using the brakes again and while we were still on the ramp; he used them to bring the aircraft to a complete stop. I was satisfied that he knew how to use them and we resumed taxiing without any issue. As we were nearing the runway; I told him to pull into the runup area. As we did; I asked him to slow down so that we could turn around and face into the wind. We did not slow down. I exclaimed to step on the brakes! He said he was on the brakes and they were not working. I realized we were nearing the edge of the runup area and were not going to stop. I promptly pulled the mixture control to idle which shut down the engine. I used my rudder pedals to steer us between the taxiway lights so that we would not hit any. We exited the taxiway/runup area and came to rest about 5-10 feet into the grass. Thankfully; there were no other aircraft in the runup area at that time and the grass area was flat. There was no damage to us the occupants; the aircraft; or the taxiway lights. After we came to rest; I informed ground control that we had exited the taxiway into the grass and they sent help to tow us back to the ramp. After returning to the ramp; myself and a mechanic inspected the brakes and found that they were working properly. Upon debrief with my student; we discovered that there is a 'ledge' pretty high above the rudder pedals which he mistook for the brakes. I also noticed that the pedals themselves are slightly smaller than most other aircraft. This most likely also hindered his attempt at finding the brakes. I am thankful that the outcome was not worse. This was a very humbling event and I will use it as a big learning experience which I will not forget for the rest of my career. I will also be much more diligent while taxiing in case an actual brake failure does ever occur.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.