Boeing Co is battling to prevent teething problems on its 747-8 freighter from turning into a wider customer revolt as jittery airlines seize on a chance to curb their exposure to a slump in the global freight market, industry sources said.

The largest plane ever built by Boeing, a stretched version of its instantly recognizable jumbo, has already been hit by a three-week-long dispute over engine performance that delayed delivery to Cargolux Airlines International, the airplane's first customer. Another buyer slashed its order by 25 percent.

Now, the fallout from underperformance risks eating into profit margins elsewhere as Boeing dangles concessions to prevent other customers from jumping on the bandwagon.

Notably, Cathay Pacific, the world's largest international air cargo carrier, reconsidered an order for 10 747-8 freighters. But Boeing assuaged the airline with concessions on a recent order for eight 777 freighters, industry sources briefed on the discussions said.

Boeing and Cathay Pacific declined to comment.

Boeing's rearguard action comes as the company disclosed a new delay to the passenger version of the 747-8 and global airlines warned of cutbacks in fleet sizes following a downturn in the cargo market.

The International Air Transport Association (IATA) warned of further declines after a significant cargo market deterioration in the third quarter. Sagging consumer confidence in the West has slowed the world's trade lanes, and Deutsche Bank said that Chinese and Indian demand was also weaker.

Boeing Watching Cargo Market

Boeing Chief Executive Jim McNerney described the fading freight market as a "watch item" when asked on a conference call with industry analysts whether the economy could affect orders for the 747-8.

"The last couple of months there has been some softening," McNerney said. "But the path on these growth curves is often up and down, quarter by quarter."

Aerospace experts say that while the 747-8 has suffered birth pangs, maneuvering by customers makes sense ahead of an anticipated economic downturn."

"The initial production batch looks underwhelming," said Teal Group aerospace analyst Richard Aboulafia. "And given that traffic numbers are underwhelming too, the incentive to defer (airplane orders) has increased significantly.

"For the past three months, the cargo numbers look an awful lot like a double dip (recession)," he said. "Cargo numbers like these are typically advance warnings of things going down."

The problems facing Boeing and its engine supplier General Electric Co fall short of the buyer rebellion and engineering bottlenecks that forced Airbus to suspend plans for a competing freighter version of the A380 superjumbo, after all its orders evaporated.

Boeing has 75 orders from eight customers for the freighter version of its updated 747, which lists at $319.3 million.

The 747-8 freighter and an upcoming passenger version promise to burn less fuel than the predecessor 747s. The plane also boasts new wings, a new tail, state-of-the-art engines and a new cockpit.

Although later batches of new airplanes often perform better than earlier ones, the darkening economic backdrop has given extra urgency to talks to shore up the 747-8, whose problems have distracted Boeing from its main priority of building more than 800 carbon-fiber 787 Dreamliners.

"Certainly further deferrals, which wouldn't be a surprise, would hurt this (747-8) program even more," said Alex Hamilton, managing director of EarlyBirdCapital. "I wouldn't argue it's an overwhelming success."

In an embarrassing setback to both Boeing and GE, Luxembourg-based Cargolux refused at first to accept the initial 747-8 aircraft because of a 2.7 percent shortfall in the performance of General Electric's engines.

The plane, originally scheduled for delivery on Sept. 19, finally left the Boeing assembly plant near Seattle for Luxembourg with little fanfare on Oct. 12.

Another customer, Atlas Air Worldwide Holdings , scrapped three out of 12 orders in September,