Silvaire LUSCOMBE 8A N2761K accident near St. Petersburg, Florida

Probable cause

The flight instructor’s and the pilot’s failure to maintain airspeed after a partial loss of engine power after takeoff for reasons that could not be determined during postaccident examination, which resulted in an aerodynamic stall and loss of airplane control. Contributing to the accident were the pilots’ decisions to operate the airplane above its maximum allowable gross weight and to perform an intersection takeoff.

NTSB analysis

The pilot/owner and a flight instructor were departing the airport, with the pilot conducting the takeoff. The flight instructor stated that the carburetor heat was off for maximum takeoff power, and stated that the engine seemed to be producing full power until the airplane reached an altitude around 100 feet. The flight instructor noted an audible loss of rpm that was confirmed by the tachometer, and stated that the engine seemed to "roll back." The airplane began to descend, the pilot applied carburetor heat, and the flight instructor assumed control of the airplane. With insufficient runway remaining on which to land, and obstacles at the end of the runway which prohibited a straight-ahead off-airport landing, the flight instructor attempted to maneuver towards the ramp area adjacent to the runway. The airplane subsequently stalled, impacted the runway in a nose-down attitude, and came to rest inverted.

Postaccident examination of the airplane revealed no evidence of any pre-impact mechanical failures or anomalies. While the takeoff was conducted with carburetor heat off despite a placard in the airplane requiring its use, the airplane's fuel state, as well as atmospheric conditions at the time of the accident, was not conducive to the disruption of fuel flow that the use of carburetor heat was intended to mitigate. The icing probability chart indicates there was potential for carburetor icing at glide and cruise power at the time of the accident. Weight and balance calculations revealed that the airplane was loaded about 68 lbs over its maximum allowable gross weight, and density altitude at the airport about the time of the accident was over 2,000 feet. Despite these factors, which would have adversely affected both the distance required for takeoff and the airplane's rate of climb once airborne, the pilots elected to conduct an intersection takeoff, thus reducing the amount of runway takeoff distance available by nearly 20%, and reducing the diversionary options available in the event of a loss of engine power.

Text from the NTSB. Open the NTSB docket for ERA12FA491 for the full record.