In November 1958, this Vertol 44A, the predecessor of the Piasecki H-21 Workhorse, was acquired by the Swedish Navy and designated Hkp1, for helicopter 1, the first type of helicopter in use by the Swedish armed forces. It served at Bromma, later at Torslanda and Berga, until 1971 when it was retired and flown to Malmen, with 3094 hours. The Hkp 1 was succeeded by the Hkp4. In May 1989, serial 01001 was first reported with the Flygvapenmuseum.

c/n is also reported as 497 but that is the line number. Delivered to the Swedish Navy as 01001 in 1958. Preserved at the Flygvapenmuseum by 1979.

The Piasecki H-21 Work Horse, or Flying Banana, was delivered to Sweden as the Vertol 44 from 1958. Receiving the local designation Hkp1, the type was used mainly by the Marinen (Navy) for transport, rescue, anti-submarine and minesweeping duties.