Blog on World of Civil Airplanes : Boeing 737

The Boeing 737 is a short- to medium-range twin-engine narrow-body jet airliner. Originally developed as a shorter, lower-cost twin-engine airliner derived from Boeing's 707 and 727, the 737 has developed into a family of nine passenger models with a capacity of 85 to 215 passengers. The 737 is Boeing's only narrow-body airliner in production, with the -600, -700, -800, and -900ER variants currently being built. A re-engined and redesigned version, the 737 MAX, is set to debut in 2017.

Originally envisioned in 1964, the initial 737-100 flew in 1967 and entered airline service in February 1968.Next the lengthened 737-200 entered service in April 1968. In the 1980s Boeing launched the -300, -400, and -500 models, subsequently referred to as the Boeing 737 Classic series. The 737 Classics added capacity and incorporated CFM56 turbofan engines along with wing improvements. In the 1990s Boeing introduced the 737 Next Generation with multiple changes including a redesigned wing, upgraded cockpit, and new interior. The 737 Next Generation comprises the four -600, -700, -800, and -900ER models, ranging from 102 ft (31.09 m) to 138 ft (42.06 m) in length. Boeing Business Jet versions of the 737 Next Generation are also produced.

The 737 series is the best-selling jet airliner in the history of aviation.The 737 has been continuously manufactured by Boeing since 1967 with 7,457 aircraft delivered and 3,044 orders yet to be fulfilled as of January 2013.737 assembly is centered at the Boeing Renton Factory in Renton, Washington. Many 737s serve markets previously filled by 707, 727, 757, DC-9, and MD-80/MD-90 airliners, and the aircraft currently competes primarily with the Airbus A320 family.There are, on average, 1,250 Boeing 737s airborne at any given time, with two departing or landing somewhere every five seconds.

#About the 373 Family

The members of the Next-Generation 737 family -- the 737-600/-700/-800/-900ER models -- continue the 737's popularity and reliability in commercial jetliner transport. The Next-Generation family has won orders for more than 6,300 airplanes, while the combined 737 family has surpassed 10,400 orders. Boeing has delivered more than 7,400 737s, and more than 4,290 Next-Generation 737s through December 2012.

The 737 program broke the record for orders for any Boeing model in a single year, accumulating 1,124 net orders in 2012. The 737 MAX - the new engine variant of the best-selling 737 - recorded 914 of those orders, bringing total orders to date to 1,064. In addition, the Next-Generation 737 set a new single-year record with 415 deliveries to customers worldwide. The 737 program also celebrated its 10,000th order in 2012.Two Next-Generation 737s were certified and entered service in 2007.

The 737-900ER (Extended Range) was launched July 18, 2005, with an order for 30 airplanes from Indonesian carrier Lion Air. The airplane was certified by the U.S. Federal Aviation Administration (FAA) on April 20, 2007, and validated by the Indonesian regulatory agency April 26. Lion Air received its first 737-900ER on April 27, 2007. Certification by the European Aviation Safety Agency followed on April 22, 2008.

On Jan. 31, 2006, the 737-700ER was launched with an order conversion from ANA (All Nippon Airways) for two airplanes. The derivative, inspired by the Boeing Business Jet, is designed for long-range commercial applications and has the longest range capability of any 737 family member in commercial service. FAA certification took place Feb. 1, 2007, with validation through the regulatory agency in Japan closely following. ANA received its first 737-700ER on Feb. 14, 2007 and its second Aug. 16.

#First three Next-Generation Models delivered between 1997-1998

Boeing certified and delivered the first three Next-Generation models in less than one year.

The 737-700 was launched in November 1993 with a Southwest Airlines order for 63 airplanes. On Nov. 7, 1997, the 737-700 was awarded type certification by the FAA, and the first delivery followed in December 1997. Europe's Joint Aviation Authority, or JAA, gave its validation Feb. 19, 1998.

The second model, the 737-800, was launched Sept. 5, 1994, with commitments for more than 40 airplanes. The 737-800 earned FAA certification March 13, 1998, and JAA type validation April 9. The first delivery was to German carrier Hapag-Lloyd in spring 1998.

Scandinavian Airlines (SAS) became the launch customer for the third model -- the 737-600 -- on March 15, 1995, when the airline ordered 35 airplanes. The 737-600 earned type certification from the FAA Aug. 14, 1998, and JAA validation Sept. 4. First delivery of the 737-600 went to SAS in the third quarter of 1998.

Between 1997 and 2003, Boeing offered the 737-900. Fifty-two of the airplanes were delivered to six customers. Launch customer Alaska Airlines received the first of 10 airplanes in May 2001. Customers began ordering the -900's replacement, the higher capacity, longer-range 737-900ER, in 2005. To date, the 737-900ER has logged more than 500 orders from 17 customers in 10 countries.

#Design

Boeing 737-700 showing the retracted landing gear, engine nacelles with flattened underside and triangular shape

The 737's main landing gear under the wings at mid-cabin rotate into wells in the aircraft's belly; the legs being covered by partial doors, and "brush-like" seals aerodynamically smooth (or "fair") the wheels in the wells. The sides of the tires are exposed to the air in flight. "Hub caps" complete the aerodynamic profile of the wheels. It is forbidden to operate without the caps, because they are linked to the ground speed sensor that interfaces with the anti-skid brake system. The dark circles of the tires are clearly visible when a 737 takes off, or is at low altitude.

737s are not equipped with fuel dump systems. The original aircraft were too small to require them, and adding a fuel dump system to the later, larger variants would have incurred a large weight penalty. Boeing instead demonstrated an "equivalent level of safety". Depending upon the nature of the emergency, 737s either circle to burn off fuel or land overweight. If the latter is the case, the aircraft is inspected by maintenance personnel for damage and then returned to service if none is found.

#Delivering values to customers is key

The 737 -- a short-to-medium-range airplane -- is based on a key Boeing philosophy of delivering added value to airlines with reliability, simplicity and reduced operating and maintenance costs. In addition, the newer 737 models offer a modern flight deck using the most advanced navigation technology available today.

Airlines can choose to provide their flight crews with either the latest display format, common with models such as the 777, or opt for data format commonality with earlier 737 models.

#A family of airplanes is range of sizes

The Next-Generation 737 family is offered in four sizes, ranging from 110 to 220 seats.

The 737-600 is the smallest member of the family and can carry up to 132 passengers.

The 737-700 is capable of carrying up to 149 passengers.

The 737-800 can seat up to 189 passengers.

Finally, the 737-900ER is the longest 737, capable of carrying up to 180 passengers in a two-class layout and is certified for up to 220 passengers in a one-class layout.

#Listening to customers

Airline customers who were involved in the development of the Next-Generation 737 models delivered a very clear message: They wanted advanced technology that allows for simplicity, reliability and low cost -- not just technology for technology's sake. They also wanted flight-deck commonality with earlier 737s.

In addition to airline customers, Boeing chief mechanics and field service representatives participated in the airplanes' development.

#A bigger wing,longer range and higher speed

The 737-600/-700/-800/-900ER models incorporate a new, advanced-technology wing design that helps increase fuel capacity and efficiency, both of which increase range. On each wing, the chord is increased by about 20 inches (50 cm) and the total span by approximately 18 feet (5.5 m). The total wing area is increased by 25 percent to 1,341 square feet (125 m²), providing 30 percent more fuel capacity for a total of 6,875 U.S. gallons (26,020 L).

New-technology Blended Winglets, which are available on the 737-700, -800 and -900ER, further boost performance. The 8-foot (2.4-m)-long wingtip extensions enhance range, fuel efficiency and take-off performance while lowering carbon emissions, engine maintenance costs and noise.

The Next-Generation 737 models fly approximately 3,000 nautical miles (5,500 km), an increase of up to 900 nautical miles over earlier 737 models. This increases 737 route capabilities throughout the world. The 737-700ER equipped with nine auxiliary fuel tanks has a maximum range of 5,775 nautical miles (10,695 km).

The advanced wing airfoil design provides an economical cruise speed of .78 Mach (590 mph). The Next-Generation 737 airplanes are capable of cruising to a maximum altitude of 41,000 feet (12.5 km), compared to 37,000 feet (11.3 km) for the 737-300/-400/-500 models, and 39,000 feet (11.9 km) for the competition.

#Advanced Engine Technology

In April 2009, Boeing and CFM introduced the new CFM56-7BE engine enhancement program to coincide with 737 airframe improvements. The combination reduces fuel consumption by two percent. CFM's engine hardware changes improve airflow, and the engine runs at cooler temperatures resulting in a one percent reduction in fuel consumption. Boeing's airplane structural improvements will reduce drag, reducing fuel use by about one percent. The combined improvements also equal a two percent reduction in carbon emissions.

Depending on an engine's thrust rating, the new engine provides up to four percent lower maintenance costs.

The CFM 56-7BE engine rolled into Boeing's production line beginning in mid-2011. Boeing will introduce its airframe improvements into production as they become available, and all will be in place by late 2013.

In 2007, CFM introduced a tech insertion package for the CFM56-7B engine. The Tech Insertion engine lowers fuel consumption by one percent over the life of the engine and lowers maintenance costs by 12 percent through longer time on wing and improved durability. The Tech Insertion engine also reduces nitrous oxide emissions by 25 percent.CFM is a joint venture between General Electric Co. of the U.S. and Snecma of France. All of its engines meet strict international emissions restrictions and when efficiently integrated on the 737, meet international noise restrictions.

The original CFM56-7 engines -- which were certified by the FAA in late 1996 at 26,400 pounds of thrust -- also offer lower fuel burn and lower engine maintenance costs. The CFM56-7B has a higher thrust capability than the CFM56-3C engines powering the 737-300/-400/-500 models. To take additional advantage of the engine's increased thrust, the newer 737 models' vertical fin and horizontal stabilizer are larger.

#737 Boeing Sky interiors Debuts

Drawing from years of research inspired by the travel experience, the 737 Boeing Sky Interior features new, modern sculpted sidewalls and window reveals that draw passenger eyes to the airplane's windows, giving passengers a greater connection to the flying experience.

The new design offers larger, pivoting overhead stowage bins that add to the openness of the cabin. The bins give more passengers room to store a carry-on roll-aboard near their own seat, adding both extra convenience and extra leg room.

Boeing redesigned reading-light switches so passengers can find them more easily and avoid accidentally pressing the flight-attendant call button.

Speakers integrated into each row's passenger-service unit will improve sound and clarity of public address operations, while the new air grill is tamper-proof and improves operational security.Deliveries of the new 737 Boeing Sky Interior began in October 2010. The program marked the 500th Boeing Sky Interior delivery in early November 2012.

#Engines

737-800 engine with non-circular "hamster pouch" inlet

Engines on the 737 Classic series (300, 400, 500) and Next-Generation series (600, 700, 800, 900) do not have circular inlets like most aircraft. The 737 Classic series featured CFM56 turbofan engines, which yielded significant gains in fuel economy and a reduction in noise over the JT8D engines used on the -100 and -200, but also posed an engineering challenge given the low ground clearance of the 737. Boeing and engine supplier CFMI solved the problem by placing the engine ahead of (rather than below) the wing, and by moving engine accessories to the sides (rather than the bottom) of the engine pod, giving the 737 a distinctive non-circular air intake.

The wing also incorporated a number of changes for improved aerodynamics. The engines' accessory gearbox was moved from the 6 o'clock position under the engine to the 4 o'clock position (from a front/forward looking aft perspective). This side-mounted gearbox gives the engine a somewhat triangular rounded shape. Because the engine is close to the ground, 737-300s and later models are more prone to engine foreign-object damage (FOD). The improved CFM56-7 turbofan engine on the 737 Next Generation is 7% more fuel-efficient than the previous CFM56-3 in the 737 classics. The newest 737 variants, the 737 MAX family, are to feature CFM International LEAP-1B engines with a 1.73 m fan diameter. These engines are expected to be 10-12% more efficient than the CFM56-7B engines on the 737 Next Generation family.

#Interior

The 737 interior arrangement has changed in successive generations. The original 737 interior was restyled for the 737 Classic models using 757 designs, while 777 architecture was used for the debut of the Next Generation 737. Designed using Boeing's new cabin concepts, the latest Sky Interior features sculpted sidewalls and redesigned window housings, along with increased headroom and LED mood lighting. Larger pivot-bins similar to those on the 777 and 787 have more luggage space than prior designs. The Sky Interior is also designed to improve cabin noise levels by 2–4 dB.The first 737 equipped with the Boeing Sky Interior was delivered to Flydubai in the fourth quarter of 2010.Malaysia Airlines, TUIFly,and Continental Airlines have also taken delivery of Sky Interior-equipped 737s.

#Demonstrates continuous improvement

The Next-Generation 737 program continuously evaluates and incorporates value-added technologies and design innovations to improve performance and capabilities. Recent offerings include short-field performance enhancements to increase payload capacity and reduce takeoff and landing field length; and carbon brakes to reduce weight for improved airplane operating economics.

Other changes include leading-edge display and flight-management software that allows the airplane to fly the most restricted navigation routes through use of industry leading Required Navigation Performance. The Next-Generation 737 is the first commercial jet airplane certified for Ground Positioning System landings, which use satellite technology to make landings more efficient, accurate, and environmentally friendly.

The Next-Generation 737 flight deck is equipped with technologies such as Vertical Situation Display, which shows the current and predicted flight path of the airplane and indicates potential conflicts with terrain; and Head-Up Display, which provides pilots with "eye-level" flight and safety information. These optional features are examples of how the Next-Generation 737 is designed to reduce flight delays, enhance safety and flight-crew efficiency.

The Electronic Flight Bag and Maintenance Performance Toolbox, available through Boeing Commercial Aviation Services, are other features that increase flight and maintenance operational efficiency.

#Operators

Merpati Nusantara Airlines 737-200 Advanced at Adisucipto International Airport, Yogyakarta

Polynesian Blue 737-800 at Wellington International Airport, New Zealand

The 737 is operated by more than 500 airlines, flying to 1,200 destinations in 190 countries. With over 10,000 aircraft ordered, over 7,000 delivered, and over 4,500 still in service, at any given time there are on average 1,250 airborne worldwide. On average, somewhere in the world, a 737 takes off or lands every five seconds.Since entering service in 1968, the 737 has carried over 12 billion passengers over 120 billion km (65 billion nm), and has accumulated more than 296 million hours in the air. The 737 represents more than 25% of the worldwide fleet of large commercial jet airliners.

Regards,