Narrative:

During a dual instruction flight in the PA-23 an incident occurred which led to an apparent prop strike on the right engine. The preflight was thorough and normal and I (instructing pilot flying in left seat) taxied the aircraft from the ramp to the run-up area at the approach end of runway xx. Prior to the run-up; my student (pilot flying in right seat working on mei rating) requested that I demonstrate a single engine failure on the takeoff roll prior to liftoff with the plan to be a full stop on the runway to which I agreed. We received clearance to depart with the tower acknowledging and agreeing to our request for a planned simulated failure on the runway and full departure once recovered. I taxied the aircraft onto the centerline; advanced both throttles to 1500 RPM; verified the engine instruments were green; and then advanced throttles to takeoff power. As the airspeed showed 'alive' I fully retarded the left throttle. The aircraft immediately started a strong veer to the left at which time I think I tried to fully retard the same throttle since my hand was currently on the left throttle only. I then realized that I didn't have the right throttle in my hand and reached up and retarded it fully. The aircraft then ran off the left side of the runway; however; I don't know if all three tires went into the grass. My student pilot stated that he noticed a runway light get hit and fly into the air; however I didn't notice this. I then guided the aircraft back onto the runway where I stopped it fully. We requested to taxi off the runway at kilo onto the inner ramp. My student then exited the aircraft while it was running to check for any obvious damage. None was noted although a deeper sound was coming from the right engine with a noticeable vibration. We then requested to taxi back to the run-up area and performed a run-up of both engines. The left ran normal and smooth; the right still had the deeper sound and increased vibration with increased RPM. We then requested a high speed taxi on the runway and ran at about 50 mph max then retarded the throttles. We then exited the runway at juliet and taxied back to the tie down spot. My student exited the aircraft prior to shut down to observe the right engine during shut down. Normal shutdown procedure was followed and then the damage to the right prop became obvious. There was an approximately one inch square piece of metal missing and a curl at the end of one of the right propeller blades.I feel the primary cause of this incident was my inappropriate reaction to the quicker than expected veering of the aircraft to the left. I should have had my right hand on the right throttle during the entire procedure so as to be able to retard power immediately. As an instructor I teach my students to always keep their hand on the throttle during and after takeoff until reaching a safe altitude. In a twin engine aircraft; the same applies for both throttles. In this circumstance I removed my hand from the right throttle to retard the left thus leaving the right unattended. Because my hand was already on the left throttle; it was not second nature for me to reach up for the right throttle. I feel this lead to the delay in recovery and the eventual incident. A secondary cause may have been an inadequate briefing of the procedure. More thorough planning may have allowed me to identify potential hazards with the procedure and therefore I could have taken steps to prevent the incident.

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Original NASA ASRS Text

Title: The Instructor Pilot aboard a PA-23 lost control of the aircraft while performing a simulated engine failure at low speed. A propeller struck a runway light when the aircraft momentarily ran off the side of the runway during the recovery.

Narrative: During a dual instruction flight in the PA-23 an incident occurred which led to an apparent prop strike on the right engine. The preflight was thorough and normal and I (instructing pilot flying in left seat) taxied the aircraft from the ramp to the run-up area at the approach end of Runway XX. Prior to the run-up; my student (pilot flying in right seat working on MEI rating) requested that I demonstrate a single engine failure on the takeoff roll prior to liftoff with the plan to be a full stop on the runway to which I agreed. We received clearance to depart with the Tower acknowledging and agreeing to our request for a planned simulated failure on the runway and full departure once recovered. I taxied the aircraft onto the centerline; advanced both throttles to 1500 RPM; verified the engine instruments were green; and then advanced throttles to takeoff power. As the airspeed showed 'alive' I fully retarded the left throttle. The aircraft immediately started a strong veer to the left at which time I think I tried to fully retard the same throttle since my hand was currently on the left throttle only. I then realized that I didn't have the right throttle in my hand and reached up and retarded it fully. The aircraft then ran off the left side of the runway; however; I don't know if all three tires went into the grass. My student pilot stated that he noticed a runway light get hit and fly into the air; however I didn't notice this. I then guided the aircraft back onto the runway where I stopped it fully. We requested to taxi off the runway at Kilo onto the inner ramp. My student then exited the aircraft while it was running to check for any obvious damage. None was noted although a deeper sound was coming from the right engine with a noticeable vibration. We then requested to taxi back to the run-up area and performed a run-up of both engines. The left ran normal and smooth; the right still had the deeper sound and increased vibration with increased RPM. We then requested a high speed taxi on the runway and ran at about 50 mph max then retarded the throttles. We then exited the runway at Juliet and taxied back to the tie down spot. My student exited the aircraft prior to shut down to observe the right engine during shut down. Normal shutdown procedure was followed and then the damage to the right prop became obvious. There was an approximately one inch square piece of metal missing and a curl at the end of one of the right propeller blades.I feel the primary cause of this incident was my inappropriate reaction to the quicker than expected veering of the aircraft to the left. I should have had my right hand on the right throttle during the entire procedure so as to be able to retard power immediately. As an instructor I teach my students to always keep their hand on the throttle during and after takeoff until reaching a safe altitude. In a twin engine aircraft; the same applies for both throttles. In this circumstance I removed my hand from the right throttle to retard the left thus leaving the right unattended. Because my hand was already on the left throttle; it was not second nature for me to reach up for the right throttle. I feel this lead to the delay in recovery and the eventual incident. A secondary cause may have been an inadequate briefing of the procedure. More thorough planning may have allowed me to identify potential hazards with the procedure and therefore I could have taken steps to prevent the incident.

Data retrieved from NASA's ASRS site as of April 2012 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.