"PX230" and "PX239", were completed for an all-weather night fighter, the Hornet NF.21. "PX239", originally built as a Hornet F.20, was outfitted with power-operated folding wings and a large dorsal fillet, which was later fitted to all production aircraft to comply with a new requirement to provide "feet off" directional stability with one engine stopped. On 25 October 1948, the first deck trials commenced on board ; these were so successful that testing rapidly proceeded to the night trials phase. On 16 May 1947, "PX230" was lost during service trials when the aircraft disintegrated in mid flight; the pilot bailed out following the breakup of the aircraft.