It takes two hundred and forty-eight factories to make a Flying Fortress.
Plants in 80 cities scattered throughout the United States are now contributing to the vastly increasing production of these famous 4-engine bombers for the US Army Air Corps and the Royal Air Force. Some 193 of these plants supply the thousands of standard equipment items and parts installed in each ship. The remaining 55 are subcontractors, now sharing the work of manufacturing major parts and subassemblies of the actual airplane.
The Boeing Aircraft Company of Seattle, headquarters of this all-American production team, has been cited as an outstanding example of successful application of the subcontracting process, which is strongly recommended by the Office of Production Management as a means of quickly accelerating the national defense program. By spreading the work over a number of existing plants, large and small, it has been possible to make immediate use of ready production equipment and qualified man power in various parts of the country and thus short-cut the task of speeding production.
While Boeing's plant expansion program has been going on, outside producers have been working all the while on their own portions of the extensive Boeing orders. As a result of this far-sighed planning, finished manufactured parts for a new Flying Fortress model are now regularly slowing into the main factor at Seattle from sources in all directions, while the Seattle factory is getting under way with its own quantity production of this model.
Boeing began many months ago to develop new sources of supply in anticipation of increased Flying Fortress production. At that time the company began placing "educational" orders for various parts normally manufactured in the Boeing plant, in order that these outside suppliers might become acquainted with the technique of aircraft production work. Insofar as possible, these "helper" plants were selected in or near Seattle in order that they might be properly coached in the work. Meanwhile, Boeing contacted other plants in more distant sections of the country to determine what would be their capabilities as subcontractors. The most promising of these were invited to send their representatives to Seattle and, at the same time, Boeing field representatives visited and surveyed the plants of the prospective subcontractors. By the time government requirements for increased production were voiced, Boeing was ready with a selected, tentative list of plants to which it could turn for assistance.
An outstanding feature of the Boeing program has been the farming out of major sub-assemblies rather than merely individual parts. Whole sections of the airplane are now being produced in completed form in outside plants and shipped to the Boeing Company for final assembly. The larges of these are built at a newly constructed plant of Boeing's, Stearman Aircraft Division in Wichita, Kansas. Here the complete tail surfaces are fabricated and assembled, as are the outer wing panels and wing tips. Other major parts now handled outside of Boeing's factory include the entire engine nacelles, engine cowling, wing flaps, landing gear, fuel tank compartment doors, fuselage circumferentials, and numerous machined parts. Boeing's own production is concentrated mainly on fuselages, inboard wing panels, and final assembly. Today approximately 30% of the Flying Fortress is built on the outside, as compared with 3% a year ago.
This outside production, Boeing officials declare, is enabling the company to make accelerated production schedules that otherwise would have been impossible. Especially has this been true in the case of machined parts. Because of the difficulty in obtaining rapid delivery of new machine tool equipment and the scarcity of additional experienced machinists, it has been particularly helpful to be able to make use of the equipment and manpower of existing machine shops, which were qualified for defense production, but were formerly occupied with other types of manufacture. By "farming out" as much of the machining work as possible, the Boeing Company has been able to relieve the load on its own greatly-enlarged machine shop, leaving the home shop in a better position to handle last-minute design changes, late production releases, "cut and try" items, and "blitzkrieg" items, which must be rushed through to hurried completion in order to prevent delays in other parts of the factor's intricately coordinated production schedule. Likewise the program has been helpful in reducing the overload on tooling facilities, which are hard pressed during expansion.
A staff of 143 persons is now at work in the Boeing Purchasing and Material Control Department, handling the meticulous job of purchasing and receiving the thousands of parts produced on the outside, including both the standard parts, which come from regular aircraft equipment manufacturers, and the parts produced for Boeing by its own subcontractors. Twenty persons are assigned completely to the job of dealing with subcontractors and following-up the coordinating their efforts. Six of these are Boeing representatives stationed at some of the larger subcontracting plants.
In arranging an outside production program for a new airplane contract, the Company management first determines in a general way the amount of work required to be "farmed out" in order to meet schedules within the limitations of available plant equipment and personnel. It then decides upon the larger units or assemblies to be handled on the outside, and determines a general tooling program by which the outside production can be undertaken and coordinated with the Company's own "inside" production. These points are determined in collaboration with the tooling, production, manufacturing, and purchasing departments, all of which make their separate survey of the problem. The production department is then responsible for the final selection of the parts to be handled as outside production.
The preliminary selection of subcontractors is made by the purchasing department on the basis of an over-all appraisal of their plant size, equipment, location, type of previous experience, and man-hour capacity for the type of aircraft work required to be done, and by the appraisal of the firm as an organization. Boeing officials point out that this last factor, the organization, has been considered most important of all ins selecting the prime subcontractors. Bids are then asked, and the actual orders are placed by the purchasing department after the production department has determined schedule requirements and has issued releases for the manufacturing work.
The production department's release will specify the quantity required, including overstock; the delivery schedule, including the minimum acceptable rate of delivery; special instructions, such as the tolerances permitted; finish specifications; tooling requirements, etc. The purchasing department cooperates with the subcontractors to fit the work to their methods and facilities. The subject of tooling is necessarily given special consideration in order that parts produced on the outside will meet rigid Boeing specifications and will fit with other parts produced in Seattle. The production department's release, therefore, details the tools, jigs, templates, etc, to be supplied to the subcontractor and the fit and interchangeability requirements. In cases where the Boeing Company already has suitable production jigs available and they can be easily transported, these are forwarded to the outside plant. In most cases, however, the subcontractor is required to build his own jigs, using Boeing master parts as guides. For example, in tooling the Stearman Division plant for the production of Flying Fortress outer wing panels, a complete master section of the outer wing, built in the Boeing plant in Seattle, was shipped to Wichita for use in aligning all the production jigs to be set up at the Stearman plant. This master wing section was built not of aluminum alloy bot of rigid steel tubes and steel plates, with all reference points and mating points located by precise methods. Similar master steel dummies of other parts were sent to other plants for aligning their jigs to insure absolute interchangeability when parts are gathered for assembly.
In many cases the Boeing Company has not only supplied detailed tooling for the outside producers, but has also supplied the necessary materials as well, either by shipping from material stocks in Seattle, or by asking the material suppliers to send direct to the new subcontractors portions of the materials which Boeing already had on order. In this way the outside producers have taken advantage of Boeing's early placement of material orders.
The Boeing purchasing department has perfected a thoroughgoing system for following up the work of subcontractors after orders have been placed, to avoid, as far as possible, the chance of bottlenecks developing unexpectedly in any particular item that would affect the master production schedules in the main plant. Progress reports are required from all the vendor companies and a file is diligently maintained, showing the status of all outside production parts. The subcontractors are notified each week of the parts and quantities which the Company expects to receive from them the following week.
To insure that the segments of the Flying Fortress coming together from various parts of the country all measure up to the high standards which Boeing sets for its own shops, a rigid system of quality control has been set up to govern all the subcontractors' work. This begins with the detailed specification, which is drawn up with great care. In the case of the larger subcontractors, Boeing representatives are on the scene not only to check the work as it progresses, but also to offer suggestions and assistance to the subcontractor.
After the parts are finished and shipped to Seattle, they pass through a careful "receiving" inspection before they are admitted to the storage racks and approved for the Flying Fortress production lines.
This article was originally published in the June, 1941, issue of Aviation magazine, vol 40, no 6, pp 74-75, 176, 186.
The PDF of this article [ PDF, 6.8 MiB ] includes 8 captioned photos showing work at various subcontractors, and a diagram showing which parts of the B-17E were being farmed out.
Photos are not credited.