(CNN) At least 61 dead after passenger plane crashes in Brazil.

The  ATR 72 twin engine turboprop had an airspeed of about 40 knots when  it was observed in a flat spin. There is a  strong historical cause for propeller driven aircraft with both reciprocating and turboprop engines.

The most likely single failure point is  the variable pitch/feathering mechanism of the left side propeller, which may have been consequent to gearbox failure. In normal operation, the angle of the propeller blades relative to the air stream is varied to run the engines at maximum efficiency.

If this adjustment is disrupted, the propeller can become a source of high drag, a windmill powered by the forward kinetic energy of the airplane. In order to fly on one engine, the blades of  the failed propeller are feathered, oriented parallel to the air stream. Failure of the propeller to feather potentiates a crash.

The result of uneven drag is adverse yaw, in this case to the left, caused by a still functioning right side engine/propeller. The pilots may have attempted to regain control by reducing power to the right engine. This would account for the low airspeed, which would not have been the choice of any pilot.

Since the advent of multi-engine variable pitch propeller aircraft, failure of a propeller to feather has been the cause of hundreds, if not thousands, of crashes.

Jet aircraft are immune to this particular problem.