Narrative:

While practicing aerobatic maneuvers (after several minutes of aerobatics; not at the beginning of the flight); the airplane roll response felt abnormal for this airplane. All maneuvers had been performed within the operating limits for this airplane. I established straight and level flight; and determined that the left ailerons were not responding to control stick inputs. The right ailerons worked normally. Note this is a biplane with ailerons on both the upper and lower wings. I established a course back to the nearest airport; home base for this aircraft; and contacted the tower to let them know I was inbound with a flight control problem. After initial radio communication with tower; I seemed to have lost the side-tone in my headset and was unsure if my transmissions were being heard by the tower. I elected to squawk 7600 to make it clear to the tower that I was having some radio issues too. I could hear their transmissions; so tower requested that I respond to their questions by pressing the identify button on the transponder. I confirmed in that manner that I was declaring an emergency. By this time; I had spent a few minutes slowing down to normal approach speed; while at a safe altitude; and determined that control authority was sufficient to continue safe flight and landing. I proceeded to the airport and landed without any further problems. Post-flight inspection of the aircraft found bolt which secures the control push rod to the bell crank to be missing; and part of the bell crank had broken off. New parts will be installed; and corresponding parts on the right side ailerons have been inspected to make sure they are in good condition. My pre-flight inspection had included a check on these bolts; and the felt secure to my fingers at that time. Several weeks prior to this incident; I had found this bolt to be loose; and did not fly the airplane that day. It was tightened by one of the other owners; and it safely flew a number of hours after this fix; without incident. The radio will also be checked prior to return-to-flight status. I did confirm that my headset is working properly by testing it in another aircraft.

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Original NASA ASRS Text

Title: A Christen Eagle II left aileron ceased responding in flight so an emergency was declared and the aircraft returned to the departure airport where the pilot discovered a push rod bolt missing and a broken aileron bell crank.

Narrative: While practicing aerobatic maneuvers (after several minutes of aerobatics; not at the beginning of the flight); the airplane roll response felt abnormal for this airplane. All maneuvers had been performed within the operating limits for this airplane. I established straight and level flight; and determined that the left ailerons were not responding to control stick inputs. The right ailerons worked normally. Note this is a biplane with ailerons on both the upper and lower wings. I established a course back to the nearest airport; home base for this aircraft; and contacted the Tower to let them know I was inbound with a flight control problem. After initial radio communication with Tower; I seemed to have lost the side-tone in my headset and was unsure if my transmissions were being heard by the Tower. I elected to squawk 7600 to make it clear to the Tower that I was having some radio issues too. I could hear their transmissions; so Tower requested that I respond to their questions by pressing the IDENT button on the transponder. I confirmed in that manner that I was declaring an emergency. By this time; I had spent a few minutes slowing down to normal approach speed; while at a safe altitude; and determined that control authority was sufficient to continue safe flight and landing. I proceeded to the airport and landed without any further problems. Post-flight inspection of the aircraft found bolt which secures the control push rod to the bell crank to be missing; and part of the bell crank had broken off. New parts will be installed; and corresponding parts on the right side ailerons have been inspected to make sure they are in good condition. My pre-flight inspection had included a check on these bolts; and the felt secure to my fingers at that time. Several weeks prior to this incident; I had found this bolt to be loose; and did not fly the airplane that day. It was tightened by one of the other owners; and it safely flew a number of hours after this fix; without incident. The radio will also be checked prior to return-to-flight status. I did confirm that my headset is working properly by testing it in another aircraft.

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.