The Sikorsky S-61N is a twin-engine medium utility helicopter with a sealed hull for amphibious operations
that can accommodate a basic crew of two and up to 26 passengers. The Sikorsky S-61N is based on the military
Sikorsky SH-3A/S61B Sea King series originally developed in the late 1950s for all-weather operations. The Sikorsky S-61B
prototype flew on 11 March 1959 and the type entered service with the U.S. Navy as the SH-3A Sea King in 1962.
The Sikorsky S-61N and its non-amphibious configurated variant Sikorsky S-61L are based on and essentially a commercial equivalent of
the militairy S-61B incorporating a number of changes, including a longer fuselage. The Sikorsky S-61L was flown for the first time on 6 December
1960 and received its FAA Type Approval on 2 November 1961. The S-61L entered production the same year. The Sikorsky S-61N with sealed hull and
stabilising SH-3's floats flew first on 7 August 1962. The S-61N version is optimized for overwater operations, particularly
oil rig support. The initial production S-61s were fitted with two 1250shp General Electric CT58-110-1 turboshafts. Both the S-61L and S-61N were
subsequently updated to Mk II standard with more powerful CT58-140 engines giving better hot and high performance and
other improvements and detail refinements. Production of the commercial
Sikorsky S-61s ended in 1979.
Helicsa Helicópteros SA registered the 1975-built Sikorsky S-61N s/n 61741 as EC-FTB in Spain on 13 August
1993. The helicopter was registered before as LN-OSY, OY-HDS, LN-OSY and EC-429. Helisca operates the EC-FTB
on behalf of the Sociedad Estadal de Salvamento y Seguridad Marítima as a SAR-helicopter along the Spanish Mediterranean Sea.
Maintenance of the Helicsa SASEMAR (Salvamento Maritimo) Sikorsky S-61N's is done by Heli-One, Stavanger.
On 11 March 2006, the Spanish helicopter made a fuelstop at Groningen Airport Eelde in the Netherlands on its way from Norway to Spain.