Boeing Co , the world's No.2 plane-maker, suffered another heavy blow to its Dreamliner project on Friday when a major customer, Australia's Qantas Airways , scrapped and deferred orders for 30 new planes.

Aviation analysts warned that more Boeing customers could follow Qantas, noting that cancellations of the fuel-efficient, long-haul plane were gaining momentum as airlines worldwide looked to conserve capital during the global recession.

Citing the tough operating environment, Qantas canceled orders for 15 of the B787-9 Dreamliners that had been due for delivery in 2014-15 and deferred for four years an order for another 15 of the same aircraft. It said the decision would save the company $3 billion in capital spending.

Qantas denied it was reacting to this week's fresh delays to the Dreamliner's development, when the first test flight was set back for a fifth time, but analysts said there was a clear risk of more order cancellations or deferrals from other airlines.

It wouldn't surprise me at all if we see more deferrals and more cancellations, particularly given the economic environment in the U.S. at the moment, it's a complete basket case, said Bruce Low, investment analyst at Australian fund manager Fortis Investment Partners.

The aviation industry is suffering very badly ... I guess the Boeing delays actually give the airlines an opportunity to pull out or defer.

Boeing's defense unit was recently hit hard by sweeping cuts announced by U.S. Defense Secretary Robert Gates in the Pentagon's fiscal 2010 budget request this year.

Even before the Qantas decision, the plane-maker had logged only nine net orders so far in 2009 as global economic weakness has spurred a string of cancellations, including 58 Dreamliners.

Rival Airbus faces the same economic pressures.

In March, Air France said it would defer taking delivery of the sixth and seventh Airbus A380 aircraft in an order for 12 of the giant planes, to save cash on down payments.

Qantas CEO Alan Joyce said in a statement that the operating environment for the world's airlines has clearly changed dramatically since Qantas announced its original B787 order in December 2005.

Qantas shares rose as much as 2.5 percent in early trade.

The stock has dived 24 percent so far this year, while the wider S&P/ASX 200 index <.AXJO> has risen about 5 percent.

Last month, Qantas said it expected to navigate the current aviation crisis, the industry's worst, without having to further cut capacity or jobs or raise capital.

But it has forecast a loss in the second half of its 2009 financial year, and announced in March it would shed 90 top management positions, adding to 1,500 job cuts announced in 2008.

Qantas said it retained the ability to buy up to 50 additional aircraft.

($1=1.245 Australian Dollar)

(Editing by Mark Bendeich & Dhara Ranasinghe)