FARNBOROUGH, England (AFP) ― The Farnborough airshow opens Monday with the non-appearance of the stricken U.S.-built F-35 fighter jet overshadowing the traditional battle for plane orders between titans Airbus and Boeing.

The F-35 stealth, whose entire fleet was grounded in the United States last week because of an engine fire, will not appear as planned on the airshow’s first day but may still take part at the end of the week, organizers said.

The key biennial event in the aviation sector calendar held south-west of London will see European planemaker Airbus and its U.S. rival Boeing look to build on robust sales of passenger planes.

Industry experts said Airbus could very likely use the event to launch an upgrade of its long-haul A330 jet ― the A330neo ― boasting more fuel-efficient engines.

On the eve of Farnborough, Boeing said it could in the future launch a new version of its 737 MAX single-aisle jet that would carry more seats.

Meanwhile a briefing update on the F-35, set to become the backbone of the air defenses of several Western countries, is scheduled to take place in Farnborough on Monday.

“Unfortunately the F-35B Lightning II will not be displaying at the Farnborough International Airshow” on the opening day, the organizers said in a statement.

“The aircraft is still awaiting U.S. DOD (Department of Defence) clearance but we are hopeful that it will fly at the airshow by the end of the week.”

Both the U.S. Air Force and Navy last week ordered a halt to all F-35 flights following a June 23 engine fire on one of the planes, which at $400 billion is the most expensive weapons project in U.S. history.

Analysts said Farnborough could see a slowdown in orders compared with previous record years, even though the industry is far from threatened.

Boeing last week forecast that global passenger numbers would grow by 5 percent annually over the next 20 years.

In the absence of truly new technologies or revolutionary materials ― such as light-weight carbon composites used in new fuel-efficient planes ― the launch of a brand new passenger jet is not envisaged before five to seven years.

This has left Airbus and Boeing to modernize current models, which they are doing with their respective medium-haul A320 and 737 planes.

Brazil’s Embraer has meanwhile launched the E2, a new version of its regional E-jets series, which could see new orders this week.

Mike Arcamone, president of commercial planes at Canadian manufacturer Bombardier, told AFP on Sunday that its CSeries single-aisle jet remained on course to enter service next year despite a suspension to test flights caused by engine problems.

Regarding modernization of long-haul planes, Boeing launched in November the 777X, a new version of its jumbo that seats between 350 and 450 passengers.

Sector watchers are now looking to see if Airbus will proceed with the A330neo.

The head of Boeing’s commercial planes division brushed aside the latest competition from Airbus.

“We believe we have the most efficient airplane,” Boeing Commercial Airplanes chief executive Ray Conner told journalists on Sunday.

Boeing last week said Dubai’s Emirates Airline had finalized an order for 150 Boeing 777 planes valued at $56 billion at list prices.

Elsewhere, Britain’s government has barred a Russian delegation from attending the Farnborough air show because of the Ukraine crisis, sparking an angry reaction from Russia.

Russia usually sends a sizeable contingent as it seeks foreign sales, notably of its Sukhoi jets.