Boeing (Chicago, Seattle and Charleston) on Friday (August 21) brought the first 737 MAX fuselage to the Renton, WA plant. The fuselage was built in Wichita, KS and transported by rail to the Washington State plant.
Boeing explains the production of the Boeing 737 over the years:
The first 271 737s were built in Seattle at Boeing Plant 2, just over the road from Boeing Field, (BFI). However, with the sales of all Boeing models falling and large scale staff layoffs in 1969, it was decided to consolidate production of the 707, 727 and 737 at Renton just 5 miles away. In December 1970 the first 737 built at Renton flew and all 737s have been assembled there ever since.
However not all of the 737 is built at Renton. For example, since 1983 the fuselage including nose and tailcone has been built at Wichita and brought to Renton by train. Also much of the sub-assembly work is outsourced beyond Boeing.
Production methods have evolved enormously since the first 737 was made in 1966. The main difference is that instead of the aircraft being assembled in one spot they are now on a moving assembly line similar to that used in car production. This has the effect of accelerating production, which not only reduces the order backlog and waiting times for customers but also reduces production costs. The line moves continuously at a rate of 2 inches per minute; stopping only for worker breaks, critical production issues or between shifts. Timelines painted on the floor help workers gauge the progress of manufacturing.
When the fuselage arrives at Renton, it is fitted with wiring looms, pneumatic and air-conditioning ducting and insulation before being lifted onto the moving assembly line. Next, the tailfin is lifted into place by an overhead crane and attached. Floor panels and galleys are then installed and functional testing begins. In a test called the “high blow”, the aircraft is pressurised to create a cabin differential pressure equivalent to an altitude of 93,000 feet. This ensures that there are no air leaks and that the structure is sound. In another test, the aircraft is jacked up so that the landing gear retraction & extension systems can be tested. As the aircraft moves closer to the end of the line, the cabin interior is completed – seats, lavatories, luggage bins, ceiling panels, carpets etc. The final stage is to mount the engines. There are approximately 367,000 parts on a 737 NG.
The present build time is now just 11 days (5,500 airplane unit hours of work) with a future target of 6 days (4,000 airplane unit hours of work). In Dec 2005 a second production line was opened to increase the production rate to 31 aircraft a month. By 2007 there was a three year waiting list for new 737s, and an order backlog of over 1,600 aircraft. A third production line is under construction dedicated to the MMA order.
After construction they make one flight, over to BFI where they are painted and fitted out to customer specifications. It takes about 200ltrs (50USgallons) of paint to paint a 737. This will weigh over 130kg (300lbs) per aircraft, depending on the livery. Any special modifications or conversions (eg for the C40A, AEW&C or MMA) are done at Wichita after final assembly of the green aircraft. Auxiliary fuel tanks and specialist interiors for VIP aircraft are fitted by PATS at Georgetown, Delaware.
The fuselage is a semi-monocoque structure. It made from various aluminium alloys except for the following parts.
- Fiberglass: radome, tailcone, centre & outboard flap track farings.
- Kevlar: Engine fan cowls, inboard track faring (behind engine), nose gear doors.
- Graphite/Epoxy: rudder, elevators, ailerons, spoilers, thrust reverser cowls, dorsal of vertical stab.
Different types of alluminium alloys are used for different areas of the aircraft depending upon the characteristics required. The alloys are mainly aluminium, zinc, magnesium & copper but also contain traces of silicon, iron, manganese, chromium, titanium, zirconium and probably several other elements that remain trade secrets. The different alloys are mixed with different ingredients to give different properties as shown below:
Fuselage skin, slats, flaps – areas primarily loaded in tension – Aluminium alloy 2024 (Aluminium & copper) – Good fatigue performance, fracture toughness and slow propagation rate.
Frames, stringers, keel & floor beams, wing ribs – Aluminium alloy 7075 (Aluminium & zinc) – High mechanical properties and improved stress corrosion cracking resistance.
737-200 only: Bulkheads, window frames, landing gear beam – Aluminium alloy 7079 (Aluminium & zinc) Tempered to minimise residual heat treatment stresses.
Wing upper skin, spars & beams – Aluminium alloy 7178 (Aluminium, zinc, magnesium & copper) – High compressive strength to weight ratio.
Landing gear beam – Aluminium alloy 7175 (Aluminium, zinc, magnesium & copper) – A very tough, very high tensile strength alloy.
Wing lower skin – Aluminium alloy 7055 (Aluminium, zinc, magnesium & copper) – Superior stress corrosion.
Many components are not built by Boeing but are outsourced to other manufacturers both in the US and increasingly around the world. This may be either for cost savings in production, specialist development or as an incentive for that country to buy other Boeing products. Here is a list of some of the outsourced components:
- Fuselage, engine nacelles and pylons – Spirit AeroSystems (formerly Boeing), Wichita.
- Slats and flaps – Spirit AeroSystems (formerly Boeing), Tulsa.
- Doors – Vought, Stuart, FL.
- Spoilers – Goodrich, Charlotte, NC.
- Vertical fin – Xi’an Aircraft Industry, China.
- Horizontal stabiliser – Korea Aerospace Industries.
- Ailerons – Asian Composites Manufacturing, Malaysia.
- Rudder – Bombardier, Belfast.
- Tail section (aluminium extrusions for) – Alcoa / Shanghai Aircraft Manufacturing, China.
- Main landing gear doors – Aerospace Industrial Development Corp, Taiwan.
- Inboard Flap – Mitsubishi, Japan.
- Elevator – Fuji, Japan.
- Winglets – Kawasaki, Japan.
- Forward entry door & Overwing exits – Chengdu Aircraft, China.
- Wing-to-body fairing panels and tail cone – BHA Aero Composite Parts Co. Ltd, China.
737 NG Key Production Dates:
17 Nov 1993: Boeing directors authorize the Next-Generation 737-600/-700/-800 program. Southwest Airlines launches the -700 program, with an order for 63 aircraft.
5 Sep 1994: The 737-800 is launched at the Farnborough Air Show.
15 Mar 1995: The 737-600 is launched with an order for 35 from SAS.
28 Apr 1995: The new engine for the Next-Generation 737 family, the CFM56-7, powers up for its first ground test at the Snecma test facility in Villaroche, France.
1 Dec 1995: Major assembly begins on the No. 1 737-700 model when a 55-foot-long spar, or horizontal wing structure, is loaded into an automated assembly tool in the Renton, Wash., factory. Assembly also begins in Wichita, Kan., on the first 737-700 fuselage Section 43 panel (an upper fuselage section).
16 Jan 1996: The CFM56-7, makes its first flight attached to the left-hand wing of a General Electric 747 flying test bed in Mojave, Calif.
20 Mar 1996: The 737-700 program reaches its 90 percent product definition release, marking a major engineering milestone for the new 737 family. The milestone signifies the transition from the development phase to production phase of the program.
22 Apr 1996: The first 737-700 machined wing ribs arrive from Kawasaki Heavy Industries in Japan. Boeing 737 wing ribs were previously built-up assemblies. The single-pieced machined ribs increase quality and decrease weight.
30 Apr 1996: The first Common Display System for the 737-600/-700/-800 flight deck arrives at the Boeing Integrated Aircraft Systems Laboratory in Seattle. The programmable software display unit allows airlines to easily maintain the flight deck and to tailor it to their specifications.
17 Jun 1996: Assembly begins in Wichita, Kan., on the No. 1 nose, or cab, section for the first Boeing 737-700.
2 Jul 1996: Boeing launch the Boeing Business Jet, derived from the 737-700 model.
15 Jul 1996: Employees at the Boeing Renton, Wash., factory unload the No. 1, left-hand 737-700 wing out of its tooling and move the approximately 50-foot-long structure to its next manufacturing position.
26 Jul 1996: The last major body structure for the first 737-700 fuselage is loaded into the integration tool in Wichita, Kan.
12 Aug 1996: Assembly begins in Wichita, Kan., on the nose section of the first 737-800.
24 Aug 1996: The first 737-700 one-piece fuselage leaves Wichita, Kan., bound for Renton, Wash.
3 Sep 1996: The first completed 737-700 fuselage arrives in Renton, Wash., after travelling nearly 2,200 miles from the Boeing Wichita plant. The first pair of CFM56-7 engines arrive at Propulsion Systems Division in Seattle for engine build-up.
18 Sep 1996: Wings are attached to the first 737-700 fuselage in the Renton, Wash., 737 factory.
6 Oct 1996: The first 737-700 fuselage rolls on its own landing gear to the final assembly area, where flight control surfaces, engine and systems are installed.
7 Oct 1996: The 23-foot, 5-inch vertical tail is installed on the first 737-700. The vertical tail weighs approximately 1,500 pounds.
10 Oct 1996: The horizontal stabilizers are attached to the first 737-700, completing the installation of all major airplane structures.
20 Oct 1996: The second 737-700 fuselage arrives in Renton from the Boeing Wichita plant.
26 Oct 1996: The first CFM56-7 engine is attached to the right wing of the first 737-700. The left-hand engine is installed the next day.
29 Nov 1996: The No. 3. 737-700 arrives in Renton from the Boeing Wichita plant.
2 Dec 1996: The first 737-700 rolls out of the Renton factory and advances into the paint hangar.
8 Dec 1996: The first 737-700 is introduced to the world at The Boeing Company’s Renton, Wash., plant. Nearly 50,000 guests attend the Next-Generation 737 celebration.
9 Feb 1997: The first Boeing 737-700 makes its maiden flight, with Boeing Capts. Mike Hewett and Ken Higgins at the airplane’s controls. At 10:05 a.m. PST, the airplane — painted in the Boeing red, white and blue livery — takes off from Renton Municipal Airport in Renton, Wash., as hundreds of Boeing employees and their families watch and cheer. After heading north over Lake Washington, the pilots fly the newest member of the 737 family north over Tattoosh, east to Spokane and then back to Western Washington before landing at Boeing Field in Seattle.
14 Mar 1997: The fuselage of the first 737-800, destined for German-carrier Hapag-Lloyd, arrives in Renton from Boeing Wichita, after traveling 2,190 miles by railcar. At 129 feet 6 inches in length, the 737-800 is 19 feet 2 inches longer than the 737-700.
11 Apr 1997: The first 737-800 rolls to final assembly for airplane systems, horizontal stabilizer and vertical tail installation.
30 Jun 1997: The first 737-800 debuts at a ceremonial rollout on the north end of the 737 final assembly factory. A crowd of several thousand Boeing Commercial Airplane employees are on hand to witness the premiere of the 129-feet-6-inch airplane — the longest 737 ever built. The first 737-800 is the 2,906th 737 built and the 6,508th commercial airplane built by Boeing in Renton.
31 Jul 1997: The 737-800 makes its first flight, with Boeing Capts. Mike Hewett and Jim McRoberts at the airplane’s controls. At 9 a.m. PDT, the 129-foot, 6-inch 737-800 takes off from Renton Municipal Airport in Renton, Wash., as Boeing employees cheer. After heading north over Lake Washington, the pilots fly north to the Straits of Juan de Fuca and conduct a series of flight tests between there and Tatoosh. Three hours and five minutes later, the airplane lands at Boeing Field in Seattle.
17 Dec 1997: Boeing delivers the first Next-Generation 737-700 to launch customer Southwest Airlines. The event is marked by a brief ceremony at Boeing Field. The airplane later departs for Love Field in Dallas, Texas.
23 Jul 2000: The first Next-Generation 737-900 stars in a ceremonial rollout at the Renton factory. Employees of launch customer Alaska Airlines and Boeing employees who worked on the 737-900 program attend the event.
12 Jan 2001: First production 737 “blended” winglets arrive in Seattle, Wash.
14 Feb 2001: The first shipset of “blended” winglets is installed during production of a Next-Generation 737 at the Renton, Wash. factory.
14 May 2004: The 1,500th Next-Generation 737 is delivered to ATA Airlines. The Next-Generation 737 family reached this milestone delivery in less time than any other commercial airplane family, six years after the delivery of the first model. The Next-Generation 737 bested the previous record holder, the Classic 737 series, by four years.
17 Jan 2005: Final assembly time for Next-Generation 737 is cut to 11 days, making it the shortest final assembly time of any large commercial jet. The feat marks a 50 percent reduction in assembly time since the implementation of Lean tactics began in late 1999.
13 Feb 2006: Delivery of the 5,000th 737.
8 Aug 2006: Rollout of first 737-900ER.
7 Feb 2014 Boeing raise 737 production to 42 aircraft a month
13 Mar 2015 New Panel Assembly Line introduced for building wing panels to reduce 737 assembly time
Top Photo: Jim Anderson/Boeing.