BOEING 737 RE-ENGINE PLAN MOVING FORWARD

August 29, 2011
Boeing will give an update on Tuesday on its plans to revamp its best-selling 737 aircraft in a bid to fight off challenges from European rival Airbus, according to people with knowledge of the matter.

The US plane maker is set to end weeks of uncertainty for investors, airlines and suppliers over the characteristics of the jet, after securing backing from its board to market a more efficient version equipped with new engines.

Boeing opted for the quick-fix "re-engining" plan, setting aside for now a longer-term redesign, after seeing Airbus grab the larger share of a record order in July from American Airlines -- once an exclusive Boeing customer.

The 737 and Airbus A320 compete in the market for jets with 150-180 seats, the biggest segment of the global jet market and estimated to be worth USD$2 trillion over the next 20 years.

"The 737 is the best-selling airplane ever," said Neal Dihora, a Morningstar analyst. "The neo (A320) came out with 1,000 order commitments within the first seven months, and I think the Boeing decision to re-engine is essentially to stem that tide from market-share losses," he added.

Boeing and its engine maker CFM International, a joint venture between General Electric and France's Safran, have been looking at installing an engine that would provide fuel savings of up to 10 percent compared with the current model, according to aerospace industry sources.

This compares with an advertised gain of 12 to 13 percent on the new engine for the A320neo, which Airbus says would save 15 percent compared to that model's basic version when including the benefits of fuel-saving wingtips.

The gap would be offset by the lower weight of the 737, producing lower proportional costs for each seat on each trip.

CFM has an exclusive agreement to supply engines for the 737 and competes with Pratt & Whitney to provide the new engines for the A320.

Boeing is seen likely to avoid the same CFM engine Airbus chose for the A320neo because it would require costly changes to the landing gear and other parts of the structure.

Originally conceived in the 1960s, the 737 sits lower to the ground than the A320, which is convenient for baggage handling but leaves less room for a bigger engine.

In modern commercial jet engines, the majority of the thrust comes from fan-driven air that bypasses the hottest part of the engine where fuel is burned.

The amount of thrust is therefore tied closely to the fan size.

The cover of the existing engine already has to be flattened to fit it under the wing, giving it a distinctive squashed look on recent models.

The name of the revamped aircraft has not yet been announced but a supplier speculated recently that it could be called the "New Evolution." The current version of the aircraft, introduced in the 1990s, is called the 737NG for Next Generation.

A Boeing spokesman declined to comment.

(Reuters)

More details emerge on configuration of re-engined 737:

More details have emerged on the likely configuration of the powerplant for the re-engined version of Boeing's 737, ahead of expected board approval for the programme.

As well as a 167cm (66in) fan on the CFM International Leap-X engine - increased from 157cm on the CFM56-7B, which powers the 737NG - the updated jet is also expected to feature external nacelle chevrons for noise reduction, similar to those featured on the 787 and 747-8.

A fan of the proposed size would remove the need to modify the design of the landing gear, although Boeing declined official comment on the deliberations on fan size.

Detailed assessments are under way to incorporate a revised tail cone, natural laminar flow nacelle and a hybrid laminar flow vertical stabiliser for additional drag and fuel burn reduction.

The airframer's board of directors was due to meet at the end of August to vote on giving a green light to the project.
Boeing is seeking to strike a balance with its design, delivering a 10-12% fuel burn improvement from the updated engine without changing the 737 too significantly and breaking commonality with its current models.
This potentially allows a way in for Airbus to offer its A320neo.

While Boeing's 167cm fan will have a lower bypass ratio and higher specific fuel consumption (SFC) than the 198cm Leap-X and 205cm Pratt & Whitney PW1100G engine options for the A320neo, the smaller engine will weigh less and create less drag on the 737's airframe.

According to one industry assessment of the engine's performance, the SFC improvement of a 167cm fan would offer around 13-14% over the 155cm CFM56-7B engine that powers the 737 today. Once integrated on to the aircraft it would deliver a fuel burn benefit of 10-12%.

A design shelved earlier this year, designated the 737RE, featured a 177cm fan, which required a 20cm nose gear extension to meet the required 43cm engine nacelle ground clearance, to avoid hitting taxiway lighting.
The 737 can accommodate up to a 170cm fan before requiring any changes to its landing gear.

According to that now-defunct plan, the longer nose landing gear would have prompted a redesign in the lower lobe of the forward 41 section, requiring Boeing to modify the electrical equipment bay to find new routes for wiring and equipment racks.

The changes would have also likely necessitated widespread modifications to the aircraft's empennage and fuselage.
Boeing is seeking to avoid repeating the trouble it encountered when developing the 747-8 freighter and Intercontinental, which began its design life as a "simple" re-engine with General Electric GEnx-2B powerplants.

The mounting of the 747's engines and stretching of the fuselage prompted significant changes to the aircraft's wing and flight control systems, which subsequently caused a ripple effect across the jumbo's design.

In turn, this drove up the extent and cost of the change required to deliver on the jet's performance targets.
Once Boeing receives the go-ahead to offer the 737-7, -8 and -9 to customers - as it harmonises the range in line with the 747 and 787 - it will be able to begin taking orders for the updated narrowbody, including firming a commitment for 100 of the type from American Airlines, announced on 20 July.

if only boeing could also eliminate the noisy sound of the engine heard in the aircraft .......