Ordered at the same time as the HC.2As, 8 Chinook HC.3s were to enter service as dedicated Special Forces helicopters. These were to be effectively low-cost variants of the US Army's SF Chinook, the MH-47G. The upgrade would include improved range, night vision sensors and navigation capability. The eight aircraft were to cost £259 million and the forecast In-Service Date (ISD) was November 1998 (defined as delivery of the first six aircraft). As work proceeded, it became evident that displays for the weather radar and other systems anticipated for an avionics upgrade programme (put to contract in 1997) would not fit inside the existing cockpit.
One potential solution was to adopt a fully digital cockpit, as used by Chinooks purchased by the Royal Netherlands Air Force. However, this was not affordable within the funding available for the HC3 programme, and a hybrid solution was adopted, incorporating elements of the existing analogue cockpit and the new digital systems and displays. In March 1998 the new ISD was set at January 2002.
The problem seems to have been a lack of definition of requirements by the Ministry of Defence. Of 100 separate requirements only 30 were defined in the contract. All the aircraft were accepted from Boeing by December 2001, meeting, and in some cases exceeding, the contract, but none have so far been accepted into service. A key issue is that the Chinook HC3's unique, hybrid digital/analogue cockpit is reliant on software to operate. However, the contract did not specify that software documentation and codes should be analysed in accordance with UK standards in order to demonstrate the integrity of the software. It has not, therefore, been possible to demonstrate that the flight instruments meet these standards. The idea that the systems would be proved by the RNAF aircraft proved unfounded due to the unique configuration of the HC3.
One of the main contractors for the avionics system has recently indicated that it would allow access to some software data. However, the process of analysis is time-consuming and expensive and, in addition, there is no guarantee of a successful outcome because the legacy software is not amenable to the techniques required to confirm the robustness of software design. Consequently, the Chinook HC3 is currently restricted to day/night flying above 500 feet in clear weather, and where the pilot can fly the aircraft solely using external reference points without relying on the flight displays. These restrictions mean that the helicopters cannot be used other than for limited flight trials.
Another problem is the corrosion allegedly suffered during storage at Boeing. It was reported in 2003 that the US Army were interested in buying the 8 HC.3s, allowing the RAF to purchase MH-47Gs. However following inspection of the aircraft the US Army declined this option. One HC.3 was damaged during delivery, rolling backwards into a crane at Bristol docks on July 20, 2001. Damage was significant but repairable. If and when the HC.3s enter service they will join 7 Squadron at RAF Odiham.
