R22 instructor pilot took control of the helicopter and made a successful autorotation after the stu...

Attributes
ACN	1111856
Time
Date	201308
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Robinson R22
Operating Under FAR Part	Other 141
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	VFR
Component
Aircraft Component	Engine Control
Person 1
Function	Instructor
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument
Experience	Flight Crew Last 90 Days 194 Flight Crew Total 1025 Flight Crew Type 1025
Person 2
Function	Trainee Pilot Flying
Qualification	Flight Crew Student
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy Inflight Event / Encounter Other / Unknown

Narrative:

We were cleared to land. My student began his pre-landing checks and disengaged the cyclic trim. The student struggled to push down the trim knob and had to apply a fair amount of pressure to get the knob to go down. When the trim went down he kept his hand there over the trim knob and mixture control which are approximately two inches apart. The student acted as if he was confused about what he had just done then began to pull the mixture full off. I attempted to stop the student from pulling the mixture but realizing it was too late and he was going to do it; I took the controls and entered an autorotation from approximately 100-150 feet and 35 KIAS. After safely setting the aircraft on the ground I notified the tower that we had landed and requested permission to change frequencies and contact my company dispatch to report the event.after speaking with maintenance personnel we deemed there was no damage to the aircraft and returned to base. I believe the event was caused by the student's momentary confusion after disengaging the cyclic trim and could have been prevented if the student took a moment to think rather than acting on the first thing that came to mind.

Original NASA ASRS Text

Title: R22 instructor pilot took control of the helicopter and made a successful autorotation after the student pilot mistakenly shutoff the mixture control.

Narrative: We were cleared to land. My student began his pre-landing checks and disengaged the cyclic trim. The student struggled to push down the trim knob and had to apply a fair amount of pressure to get the knob to go down. When the trim went down he kept his hand there over the trim knob and mixture control which are approximately two inches apart. The student acted as if he was confused about what he had just done then began to pull the mixture full off. I attempted to stop the student from pulling the mixture but realizing it was too late and he was going to do it; I took the controls and entered an autorotation from approximately 100-150 feet and 35 KIAS. After safely setting the aircraft on the ground I notified the Tower that we had landed and requested permission to change frequencies and contact my Company Dispatch to report the event.After speaking with Maintenance personnel we deemed there was no damage to the aircraft and returned to base. I believe the event was caused by the student's momentary confusion after disengaging the cyclic trim and could have been prevented if the student took a moment to think rather than acting on the first thing that came to mind.

Data retrieved from NASA's ASRS site as of July 2013 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.