PARIS — The Amos-5 telecommunications satellite launched in December 2011 for commercial fleet operator Spacecom of Israel has suffered a failure of one of its on-board motors that likely will reduce the satellite’s expected service life, Spacecom said.

The company said Amos-5’s prime contractor, ISS Reshetnev of Krasnoyarsk, Russia, estimates that the failure could trim about a year from Amos-5’s expected 15-year operating life, or perhaps more depending on how the situation develops.

A Spacecom official said the manufacturer is evaluating possible mitigation measures that may mean no service-life reduction. In any event, the official said, Amos-5’s customers are not affected by the on-board problem.

The company’s announcement to the Tel Aviv Stock Exchange nonetheless spooked investors into a sell-off that drove Spacecom’s stock price down by 19.4 percent in the three days ending Oct. 24.

Amos-5 represented a rare commercial win outside the domestic Russian market for ISS Reshetnev. It was also an unusually inexpensive purchase by Spacecom. The satellite carries a C-band payload of 14 72-megahertz transponders and four 36-megahertz transponders, and a Ku-band payload of 18 72-megahertz transponders with three regional beams for Africa, Europe and the Middle East.

Amos-5 operates at 17 degrees east, a new orbital slot for Spacecom, which is targeting Africa as its first big foray outside of its home region. The satellite was more than half booked on launch.

Amos-5 uses ISS Reshetnev’s Express-1000H platform and is designed to provide 5.9 kilowatts of power to the payload at the end of its life. After its launch, Spacecom officials said it carried enough fuel to continue full service well beyond the 15-year contracted in-orbit life.

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Peter B. de Selding was the Paris Bureau Chief for SpaceNews.