[1][2] The larger aircraft was required to fulfil a number of roles, including observation and liaison duties, casualty evacuation and glider towing.

It was required to give a good view in all directions for the observation role, and to operate out of short airstrips and to be easy to maintain in the field.

Tests showed that the aircraft had a dangerous habit of losing height when flaps were retracted after take-off, while ground handling was also poor.

[4] Also in 1951, Praga proposed a crop-spraying version, the E-55-H, which would be fitted with a tank for 250 kg (550 lb) of chemicals, but this remained unbuilt.

[3] It was badly damaged in a landing accident at Mladá Boleslav on 29 June 1953, and was not repaired, and was scrapped, with its wing being used as a training aid at the Brno military academy, while its engine was used in the prototype Zlín Z-226.