The Westland Sea King HC4 / Westland Commando is a twin-engine medium commando assoualt and utility helicopter with a sealed hull for amphibious operations
that can accommodate a basic crew of two and up to 28 fully equiped troops. The Westland WS-61 Sea King is a Sikorsky S-61 built under licence by Westland Helicopters.
The Sikorsy S-61 itself 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 military 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.
Royal Navy Westland Sea king HC.4 / Commando c/n WA960 was flown first on 3 June 1986 and delivered as ZF115 to the Royal Navy / Royal Marines
transport on 3 July 1986. On 30 November 2001, Commando HC.4 ZF115 was involved in an air incident at Boscom Down and the airframe sustained
extensive structural damage. The damaged airframe was subseqeuntly held in storage until Vector Aerospace Helicopter Services was awarded a
contract in 2007, to repair the aircraft and bring it up to the latest modification standard. On 2 April 2009, Vector Aerospace Helicopter
Services Fleetlands performed the formal handover of Sea King MK4 ZF115 back to the MoD after an extensive repair, modification and maintenance
programme. The ZF115 from 848 Naval Air Squadron was painted in an 'Arctic' camouflage with additional "Sea King 40th anniversary 1969-2009" titles.
When seen at Groningen Airport Eelde in the Netherlands on 31 May 2011, the Royal Navy Westland Sea King HC.4 / Commando ZF115 wear still its special
"Sea King 40th anniversary 1969-2009" colours.