A further issue that adversely affected early twin-engined aircraft was the use of fixed pitch propellers that could not feather. The asymmetric drag introduced by a dead engine with such a propeller was a serious problem in a twin engined aircraft, particularly on take-off. Variable pitch propellers were an important, but often overlooked, refinement that was introduced with the DC-2 and Boeing 247. Nevertheless, even some later twin engined aircraft could be a handful in single engined flight.
In the case of the Italian aircraft, there were also reliability issues with the more powerful two row radial engines.