This aircraft was constructed by Sikorsky Aircraft Division in Stratford, USA, back in 1958. It was first operated in the US as N824T
, but was later sold to the Swiss company Eisenhut Aviation in 1972 (registered HB-XDS
on April 11 the same year).
Eisenhut Aviation used the machine for approx five years, leasing it to various operators. It left Switzerland several times - in 1973 the Spanish company Helicsa used the helicopter in SAR operations and in 1974 Sued Helicopter used the machine for EMS purposes in Germany. However the most frequent operator of HB-XDS
became the genuine Swiss company Heliswiss.
At that time the owner of the Swedish company Norrlandsflyg, Knut "Knutte" Hedström, was searching for a large and practical helicopter in the size of a Bell 205, but with a more reasonable price. In 1975 he had purchased a Sikorsky S-55 (SE-HGZ
) which had been modified to a T-version by the Swiss company Pilatus. However that helicopter wasn't enough, he needed yet another machine. In 1977 Norrlandsflyg purchased Eisenhut Aviation's T-modified HB-XDS
via Pilatus. The helicopter was registered SE-HHY
in April 1977 and brought to the Swedish town of Gällivare, the heart of Norrlandsflygs operations.
The S-55 was very well suited for passenger- and cargo transports since the pilot sits separated from his load. You could practically fill the cabin from floor to ceiling but still fly away unaffected. Another advantage was the safety aspect: the high mounted main- and tail rotors made the aircraft very safe on the ground. The risk of getting skis or fishing gears in the main rotor is very low. The passenger seats could easily be removed if needed, offering a square formed cabin floor without any aerodynamic airframe design in the way. At the most the helicopter could carry up to 10 passengers and 2 pilots.
Norrlandsflyg mainly used the aircraft for passenger transports in northern Sweden. Unfortunately SE-HHY
only stayed in service for two years. On August 15, 1979, while taking off from Sitasjaure (near Ritsem), the aircraft struck a power line and crashed. Five people lost their lives in the tragic accident.
The S-55T proved itself more than capable of operating in the most northern parts Sweden, flying heavy and uncomfortable loads in the harshest environments. In fact the sister ship of this aircraft, SE-HGZ
, stayed in service with Norrlandsflyg for almost 30 years!