Narrative:

The aircraft took off from addison, tx, at about PM00 hours local time feb/fri/92. During the climb out the plane experienced a moderate level of vibration of unknown origin. As the plane leveled off and setup for cruise, the vibration ceased. Due to this, I maintained a scan that included the engine instruments more often. The rest of this leg of the flight, to denton to practice some approachs, went on without incident. After 1 approach, we decided to land and stretch out legs. 15 mins after shutdown the plane would not start, so I pulled the propeller through myself to get it running. That was a first for me. Again, on takeoff we felt that same vibration, and on a heading of about 170 degree, runway heading, we climbed out to 2300 ft MSL. We then turned to 120 degree to return to addison. We flew for about 5 min on this heading and sighted ahead what we thought was lake lewisville dam. We called in to addison our intention to land, and was told to enter a left downwind close in, to avoid the dfw TCA. A few seconds after making that call, I realized that we were approaching lake grapevine, north of dfw. We immediately turned northeast and descended to 1900 ft. We proceed to addison without further incident. We had flown too far south on our takeoff from denton, before turning east, because we were trying to discover the origin of the vibration, and I was also still thinking about having to hand-start the plane. These 2 factors and some inattn caused us to mis- identify the lake we were approaching. We felt that our position as we approached the lake was very close to TCA boundary and took immediate action, we turned and descended to arrive at a location that we were sure was out of the TCA.

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Original NASA ASRS Text

Title: SMA BECOMES DISORIENTED AND ENTERS THEN EXITS TCA.

Narrative: THE ACFT TOOK OFF FROM ADDISON, TX, AT ABOUT PM00 HRS LCL TIME FEB/FRI/92. DURING THE CLB OUT THE PLANE EXPERIENCED A MODERATE LEVEL OF VIBRATION OF UNKNOWN ORIGIN. AS THE PLANE LEVELED OFF AND SETUP FOR CRUISE, THE VIBRATION CEASED. DUE TO THIS, I MAINTAINED A SCAN THAT INCLUDED THE ENG INSTS MORE OFTEN. THE REST OF THIS LEG OF THE FLT, TO DENTON TO PRACTICE SOME APCHS, WENT ON WITHOUT INCIDENT. AFTER 1 APCH, WE DECIDED TO LAND AND STRETCH OUT LEGS. 15 MINS AFTER SHUTDOWN THE PLANE WOULD NOT START, SO I PULLED THE PROP THROUGH MYSELF TO GET IT RUNNING. THAT WAS A FIRST FOR ME. AGAIN, ON TKOF WE FELT THAT SAME VIBRATION, AND ON A HDG OF ABOUT 170 DEG, RWY HDG, WE CLBED OUT TO 2300 FT MSL. WE THEN TURNED TO 120 DEG TO RETURN TO ADDISON. WE FLEW FOR ABOUT 5 MIN ON THIS HDG AND SIGHTED AHEAD WHAT WE THOUGHT WAS LAKE LEWISVILLE DAM. WE CALLED IN TO ADDISON OUR INTENTION TO LAND, AND WAS TOLD TO ENTER A L DOWNWIND CLOSE IN, TO AVOID THE DFW TCA. A FEW SECONDS AFTER MAKING THAT CALL, I REALIZED THAT WE WERE APCHING LAKE GRAPEVINE, N OF DFW. WE IMMEDIATELY TURNED NE AND DSNDED TO 1900 FT. WE PROCEED TO ADDISON WITHOUT FURTHER INCIDENT. WE HAD FLOWN TOO FAR S ON OUR TKOF FROM DENTON, BEFORE TURNING E, BECAUSE WE WERE TRYING TO DISCOVER THE ORIGIN OF THE VIBRATION, AND I WAS ALSO STILL THINKING ABOUT HAVING TO HAND-START THE PLANE. THESE 2 FACTORS AND SOME INATTN CAUSED US TO MIS- IDENT THE LAKE WE WERE APCHING. WE FELT THAT OUR POS AS WE APCHED THE LAKE WAS VERY CLOSE TO TCA BOUNDARY AND TOOK IMMEDIATE ACTION, WE TURNED AND DSNDED TO ARRIVE AT A LOCATION THAT WE WERE SURE WAS OUT OF THE TCA.

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.