Narrative:

On a training flight with one of my students, we encountered loss of aileron control. We had just recovered from slow flight, when I asked her to make a turn. She said she couldn't, so I took the controls and attempted the turn. It was as if the controls were frozen. I still had elevator control, but not aileron control. I recycled the flaps thinking that maybe the ailerons were stuck. After several attempts to manipulate the controls, I decided it was best to land. I called norfolk approach and declared an emergency. I decided to land in chesapeake as it was a smaller airport (less rerouting of traffic) and it was closer. I landed without incident and secured the aircraft on the ramp. Several hours later, my boss told me that my student had unknowingly hit the autoplt engage button. When it engages, it gives no indication of being on and automatically goes into 'stabilize' mode, which would render the controls useless. There is a small light that illuminates when it is on, but is on the far left side and out of my view. The autoplt experience I have is with system that keep headings, altitudes, and rates of climb. Also, in my experience, an autoplt would allow control movement. I did not think to check the autoplt because I had not engaged it or given it an assigned heading. I have always thought of wing-levelers being on larger aircraft.

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Original NASA ASRS Text

Title: C172R FLT CREW HAS CTL PROB, DECLARES AN EMER AND DIVERTS TO CPK.

Narrative: ON A TRAINING FLT WITH ONE OF MY STUDENTS, WE ENCOUNTERED LOSS OF AILERON CTL. WE HAD JUST RECOVERED FROM SLOW FLT, WHEN I ASKED HER TO MAKE A TURN. SHE SAID SHE COULDN'T, SO I TOOK THE CTLS AND ATTEMPTED THE TURN. IT WAS AS IF THE CTLS WERE FROZEN. I STILL HAD ELEVATOR CTL, BUT NOT AILERON CTL. I RECYCLED THE FLAPS THINKING THAT MAYBE THE AILERONS WERE STUCK. AFTER SEVERAL ATTEMPTS TO MANIPULATE THE CTLS, I DECIDED IT WAS BEST TO LAND. I CALLED NORFOLK APCH AND DECLARED AN EMER. I DECIDED TO LAND IN CHESAPEAKE AS IT WAS A SMALLER ARPT (LESS REROUTING OF TFC) AND IT WAS CLOSER. I LANDED WITHOUT INCIDENT AND SECURED THE ACFT ON THE RAMP. SEVERAL HRS LATER, MY BOSS TOLD ME THAT MY STUDENT HAD UNKNOWINGLY HIT THE AUTOPLT ENGAGE BUTTON. WHEN IT ENGAGES, IT GIVES NO INDICATION OF BEING ON AND AUTOMATICALLY GOES INTO 'STABILIZE' MODE, WHICH WOULD RENDER THE CTLS USELESS. THERE IS A SMALL LIGHT THAT ILLUMINATES WHEN IT IS ON, BUT IS ON THE FAR L SIDE AND OUT OF MY VIEW. THE AUTOPLT EXPERIENCE I HAVE IS WITH SYS THAT KEEP HDGS, ALTS, AND RATES OF CLB. ALSO, IN MY EXPERIENCE, AN AUTOPLT WOULD ALLOW CTL MOVEMENT. I DID NOT THINK TO CHK THE AUTOPLT BECAUSE I HAD NOT ENGAGED IT OR GIVEN IT AN ASSIGNED HDG. I HAVE ALWAYS THOUGHT OF WING-LEVELERS BEING ON LARGER ACFT.

Data retrieved from NASA's ASRS site as of July 2007 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.