[5] The two-seat version was modified into the S-52-2, a four-seat helicopter using a 245 hp (183 kW) Franklin O-425-1 air-cooled flat-six, which was moved slightly to the rear to accommodate the enlarged cabin.

[4] In September 1952, eight S-52-3 aircraft were delivered to the U.S. Coast Guard as the HO5S-1G, but were found to be too slow, small, and short-ranged for search and rescue, and were placed in storage beginning in April 1954.

[4] Many former military S-52 aircraft were demilitarized, rebuilt, and licensed for civil use, and in 1964, Orlando Helicopter Airways (OHA) acquired the type certificate and parts inventory from Sikorsky.

[4][9] In the early 1960s, OHA founder Fred Clark had used a fleet of three S-52 aircraft for powerline inspections and to shuttle VIPs and members of the news media between Orlando, Florida, and the Kennedy Space Center at Cape Canaveral.

OHA would eventually acquire at least 17 S-52 aircraft, which were extensively used for long-distance powerline inspection flights—a role that Clark found the S-52 to be well suited for, as it was more comfortable to fly and had a longer range than the then-prevalent Bell 47.

OHA had a hurricane-damaged former Marine Corps HO5S-1 in storage, and using NASA funds, the aircraft was rebuilt with four salvaged 60 hp (45 kW) electric starter motors from disused turboshaft engines along with fourteen 72V lead-acid batteries.

OHA obtained additional funding from NASA, hoping to replace the troublesome four-motor setup with a single 240 hp (180 kW) torpedo motor that would eliminate the transmission, but was unable to obtain the desired motor from the U.S. Navy; OHA consequently stored the aircraft indefinitely in 1984 and the project was eventually abandoned.