aerodynamic features and low structural weight. The design also benefitted from an advanced fail-safe structure, the majority of which having been milled in accordance to Dassault's traditional military manufacturing practices. The Mercure featured in-house-developed triplicated, fail-safe hydraulic flight control system and the flight controls lacked any manual reversion. Air conditioning also featured independent duplicated systems with a cross-feed tapped from the engines compressors along with, unusually, the auxiliary power unit for use during takeoffs and on the ground, as well as in the instance of a double-engine failure scenario. The electrics were composed of a pair of independent 120/128 volt three-phase 400 Hz AC systems fed via engine-driven alternators, while a third AC system was driven by the APU. There are also three independent 28 volt DC sources. Operational history Intending for the Mercure to be mass-produced in substantial numbers (According to Flight International, the 300th aircraft was projected to be delivered by the end of 1979), Dassault established a total of four plants especially for the Mercure program: Martignas (close to Bordeaux), Poitiers, Seclin (close to Lille) and Istres. Additional manufacturing work was distributed across locations throughout Europe, the production programme being a collaborative effort between Dassault, Fiat Aviazione of Italy, SABCA (Société Anonyme Belge de Constructions Aéronautiques) of Belgium, Construcciones Aeronáuticas SA (CASA) of Spain and the Swiss National Aircraft Factory at Emmen, all of which acted as risk-sharing partners in the venture. On 30 January 1972, Air Inter placed an order for ten Mercures, which had to be delivered between 30 October 1973 and 13 December 1975. At this point, the break-even point was anticipated to be around 125–150 aircraft. However, due to the lack of other orders, the production line was shut down on 15 December 1975. Only a total of two prototypes and ten production aircraft were built. One of the prototypes (number 02) was eventually refurbished and purchased by Air Inter to add it to its fleet. On 29 April 1995, the last two Mercures in service flew their last commercial flights. Throughout their combined cumulative operational lifetimes, the Mercure accumulated a total of 360,000 flight hours, during which 44 million passengers were carried across 440,000 individual flights without any accidents occurring, and a 98% in-service reliability. Operators Air Inter Surviving aircraft F-BTTB, c/n 2 is on display at the Technik Museum Speyer in Germany. The cabin of the aircraft, although closed to the