Ariane engine builder Société Européenne de Propulsion (SEP) has decided to change the Vulcain cryogenic motor which should have boosted the Ariane 5 heavy duty rocket on its next flight in mid-September.
This follows a problem detected during a bench trial test of a similar engine destined for a later flight.
"SEP has encountered a hitch, and we have decided to change the engine for Flight 502," Roger Vignelles, SEP chairman and chief executive officer, said at the Paris Show.
This is expected to take a fortnight, but may cause delays beyond the next set date, possibly going to the end of the year.
Already, Flight 502 has been postponed several times after the disastrous Flight 501 on 4 June 1996, when the rocket blew up in mid-air 30sec after blastoff.
A recent bench test (known as an 'acceptance' test) of a Vulcain engine to reach the 115-tonne thrust intended for Flight 504 was stopped about 300sec into the scheduled 600sec. A problem developed in a component made of silver in the engine's LOX (liquid oxygen) turbo pump.
SEP, which had changed suppliers of this component, considers that deterioration of the metal, compared with the component provided by the previous manufacturer, may have something to do with the cause of the defect.
Supplier
SEP has therefore ruled that the Vulcain engine initially intended to go on Flight 503 manufactured by the previous supplier, should power Flight 502.
As of April 1997, the Vulcain engine had exceeded 100,000sec of cumulated bench test operation, against a nominal time for each flight of 600sec.
The Paris-based European rocket building consortium has 14 Vulcain engines on order featuring an improved hydrogen turbopump.
SEP is developing a Vulcain cryogenic engine, fuelled by liquid hydrogen and liquid oxygen, for future Ariane 5 launches.
Source: Flight Daily News
