The S-55 was the first helicopter with both the space and power to carry large loads. It was in heavy demand by both civil and military operators. Okanagan Helicopters operated 21 S-55s while the RCAF flew 15 transport versions and the RCN operated 13 HO4S-3. A total of 1 100 were built in the United States and a further 550 in other countries. The HO4S-3 retired from Canadian service in 1970.
The S-55 was the world’s first certified transport helicopter, the first helicopter to fly the Atlantic, and the first equipped with anti-submarine sonar and torpedoes. The HO4S-3 was used by the RCN to develop and test "Beartrap" equipment which allowed large helicopters to operate from anti-submarine frigates in the open ocean.
The Museum specimen was made in 1955 for the RCN. During its career the Museum HO4S-3 is credited with rescuing 32 people, three dogs, and a cat from various marine disasters. It served with the navy until donated to the Museum in 1970.