Tests on the launcher's cryogenic main stage have been under way in Kourou for a year and were to have ended in the third quarter of 1995 with the subassembly's qualification. Many positive results were obtained over the summer but it was not possible to achieve some of the objectives set for that period and a number of malfunctions disrupted the tests, mainly as a result of problems encountered with operation of the ground facilities.
In addition, a leak in the oxygen feed line in the upper part of the stage and a hydrogen leak at thrustframe level made it necessary to improve the leak-tightness devices in a number of circuits.
Lastly, an incident on 1 September affecting the actuator system in the Vulcain cryogenic engine led the board set up to analyse the problem to conclude that the fault lay in the high-pressure oil distribution system, which was subject to a water-hammer effect. Measures were immediately taken to reinforce the circuit and repair work on the Vulcain engine was completed. An overall verification test without a firing will be carried out early in October to validate the changes made to the stage. It will also provide an opportunity to check that the test systems are operating properly.
A detailed review of the time schedule has been carried out to take account of the qualification objectives that have already been met and those that remain for the launcher as a whole (systems, stages, subassemblies and ground facilities).
All this work means that the start of the 501 campaign is now planned for early February 1996 with a view to the 501 flight taking place in late April and the 502 flight in September. The European Space Agency has delegated the management of its Ariane-5 programme to CNES, the French space agency.
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