General Aviation News will often reprint excerpts from accident reports made by the US National Transportation Safety Board (NTSB), including a June 2010 report about an accident that involved a Rans Coyote II S6 that caused two fatalities in Lincoln (California).
According to the accident report, the pilot (who had about 380 hours) had removed the doors of his two-seat, 65-hp plane and flew it without incident the day before the accident. However, the aircraft’s documentation noted that climb and cruise performance would be reduced when the doors were removed.
When the accident occurred, the pilot had taken off with a passenger and without the doors. According to a witness, the aircraft was returning to the airport at 500 feet and turned downwind with another aircraft in a traffic pattern ahead of the accident plane. It then:
…entered a left bank of approximately 35° to 40°, presumably to increase the spacing between aircraft. According to witnesses, the plane appeared to be traveling slower than normal. During the turn, the left wing dipped and the airplane entered a descending spiral and crashed.
An examination of the wreckage did not find any pre-impact mechanical issues.
Hence, the probable cause of the accident was the pilot’s failure to maintain adequate airspeed while in a turn. This caused an aerodynamic stall and a loss of control. However and contributing to the accident was the increased drag on the aircraft because the doors had been removed.
In other words and if you are going to make a major modification to your aircraft (like removing the doors), be sure you have read all of the documentation that came with your aircraft and understand the potential ramifications of your modification.