Avengers By Eastern

by Herbert Chase
Many stations, each with few operations and maximum break-down into subassemblies, help General Motors' aircraft division expedite production of famed Grumman-designed Navy torpedo bomber planes.

Everybody knew that a tough job had to be done when part of the fabrication and all the final assembly of the Navy's Avenger torpedo plane were assigned to a plant of the Eastern Aircraft Div, General Motors Corp. The Division's chief asset was a group of engineers and executives possessing a good knowledge of quantity production methods (though none had been in aircraft work) and plants, one of which happened to include a long high bay served by a crane. This latter was adaptable to the assembly of a plane having a fairly large wing spread.

Engineers and production men were, and still are, keenly aware that aircraft manufacture presents its own difficult problems and that it would not be easy to acquire the "knowhow" quickly. This is especially true of a plane which is among the more complex types. Besides having to learn lessons in fabrication, it was necessary to triple personnel and to train not only the supervisory force but the whole group of workers retained, plus twice as many more who possessed little or no factory experience, including a large proportion of women.

Naturally, the organization was greatly aided by Grumman Aircraft Engineering Corp, which designed the Avenger and already had it in production. Eastern's supervisors were given the benefit of Grumman skill and every facility for learning how Grumman did the job. Just as naturally, efforts were made to apply the prior knowledge of quantity manufacture of Eastern's organization, and to adapt it to the solution of the problems faced, where this seemed promising. There is, however, a vast difference between the manufacture of a few thousand sets of automobile hardware per day (the prewar job done in the plant here referred to) and the making of a relatively few large and intricate planes in the same time.

Fortunately, parts of the job were assigned to other Eastern plants. One plant took on the manufacture of wings. Another is making the rear fuselage and tail surfaces, and still another supplies tubing and electrical subassemblies The engines, turrets, struts, and many other component come from other suppliers. This leaves the plant here dealt with to fabricate the forward fuselage section and the center wing section as the only large major units, but numerous smaller subassemblies are made and a host of other element are received as small parts, complete units, or minor subassemblies.

Most of the plant considered here consists of alternate high and low bays, none of which could accommodate a large assembled plane. As some bays were not high enough for building an entire fuselage, the main assembly line follows high bays, with the intervening bays being used partly for storage, for making and repairing tools, and for the assembly of small units and parts. These areas are as convenient as possible to the points where the units built are needed in the final assembly.

At the end of the fuselage assembly line, the fuselage enters the wide crane bay and receives its wings, among several other major parts. Because of the height of the fuselage and the need for doing much work above wing level, high bays are equipped with fixed balconies along the edge of which the fuselage, on a wheeled dolly at floor level, is advanced. This makes it easy for workers to enter the cockpits at a high level and to do many jobs which otherwise would require high and bulky scaffolds. Others work from floor level. This arrangement facilitates the supply of small- and medium-size parts which are needed at both levels, and gives bench space for certain operations which cannot be done in prefabricating departments. Many small parts needed in assembly work and all tools for assembly operations are kept in bins, racks, or lockers on both levels.

Remaining portions of the plant, comprising about half its area, are given over to basic fabrication and building of two large and several small subassemblies, as noted above. Such departments as the press room, router department, hammer room, welding department, anodizing, heat-treatment, and painting departments take about one-fourth of the plant. These, together with a machine shop, which is on the second floor over one side of the plant, feed fabricated parts into the major and minor subassembly departments. At the proper time, small subassemblies are advanced to the fuselage assembly and main assembly lines. Fabricated units coming from other plants are fed in where needed in the respective assemblies.

All the large subassemblies which enter into the main fuselage assembly are built in fixtures similar to, though not identical with, those employed by Grumman. Policy has been to break down into small subassemblies as many as possible of the elements which are needed in the large subassemblies. In other words, instead of centering the work largely in big fixtures in and around which many workers must perform many operations, these jobs are divided so that they are done at many separate stations. At each of these is usually a smaller fixture where one or only a few workers perform relatively short repetitive jobs, always with ample space.

These fixtures assure fits when the small subassemblies are transferred to the larger fixtures. This method also has the great advantage that workers can quickly learn their jobs, since the work is simple and often repeated, and that a large number of individuals contribute to the large subassembly without getting in each other's way. Moreover, by employing assembly fixtures as well as numerous drilling jigs from the smallest subassemblies upward, precise interchangeability is promoted. When a small subassembly reaches the next larger subassembly it fits and is built into the larger subassembly with a minimum of labor.

As far as possible, assembly lines are set up for a regular progression from station to station and so that progression is toward larger and larger assemblies. Most smaller assemblies are shifted from station to station by hand, as they are light and the distances small. Racks for small banks of parts are provided between many stations so that any unforeseen delays at one station will not result in stoppage at following stations. Most large subassemblies are shifted to the next fixture on dollies, but where necessary trolley rails are provided for shifting from fixture to dolly.

Assembly of the major fuselage units is effected in a series of large splicing fixtures which occupy much of one high bay. The major locating points on these fixtures are supported on concrete piers and are checked for alignment by transit before each major assembly is started. Include in this assembly are the forward fuselage (to which a firewall built in another plant has been added), a center wing section, and a rear fuselage, the latter also coming from another plant.

The primary work done in these large assemblies is to splice these sections together. When completed, the assemblies are lifted by power hoists and are set into dollies which are wheeled along a guide rail paralleling the fixture line When in the dollies, the assemblies undergo Navy inspection and any faults are remedied before the assemblies are cleaned of chips and advanced into a closed spray room for painting

The dollies, which differ from those employed by Grumman and do not include any scaffolds, are advanced parallel to the axis of the fuselage and have four wheels which run on guide strips, except on turns. There the guiding is done by the center floor chain rail, the dollies being attached to the chain when they issue from the paint room. Dollies are, essentially, long narrow platforms about a foot above the floor. Fastened to the platform frame are four uprights which support the fuselage at four points, two near the forward end and two on a bar passed through a transverse tube built into the tail section of the fuselage.

Each dolly has numerous air and electric outlets to which portable power tools and lights are connected. These are tapped off through lines fastened to the dollies, and there are flexible connections between the dollies, so that the whole row at each side of each high bay is fed in series. Leads for these lines are swung overhead at the center of each bay, and the foreman in that bay must see that lines are plugged in and disconnected within a certain marked distance. As conveyor motion is extremely slow, connections do not have to be changed often and there are always a least two feed lines connected, except at the instant of the shift. As only one line is shifted at a time, the dollies are never without power. Leads are supported from overhead and thus are kept off the floor.

Dollies are so guided that the fuselage follows along the balconies, the low point of which just clears the top of the stub ends of the wing center sections. This makes it easy for assemblers who work from the balconies to enter either cockpit or to reach a platform which projects beyond the firewall at the front end. Each balcony has rope railings which are detachable in short lengths and which are replaced after the fuselage passes a given point.

Much of the work, especially in the bomb bay, is performed by employees at floor stations and is done from the dolly platform or from small one- or two-step movable platforms set on the main platform. A few exterior jobs make it necessary to use light four-step units which are attached temporarily to the dollies and have wheels which run on the floor. In some areas, especially near the end of the fuselage line, wheeled scaffolds have to be attached to the dollies to reach points not accessible from the floor balconies.

In all, the final assembly line is nearly mile in length, yet because it makes several loops the area occupied is comparatively compact. Although balconies run along each side of the high bays, there is plenty of room for the fuselages to pass along one side of the bay and back along the other with space between, before being shifted, while still on the dollies, to the next high bay. There are over 100 stations on the line and their average length approximates 40 ft. At each station, a given set of operations must be performed and each assembler (there are often several at a station, a large proportion of them women) has a specified part of the work to do and soon becomes expert in this job.

In an emergency, the assembler can ride beyond his or her station, usually without interfering with other assemblers. Since the operations have been carefully timed, however, there seldom is need for doing this. In the low bays between the higher ones are separate groups of assemblers who prepare wiring and tubing among other subassemblies and have them ready as needed.

A great part of the work along final assembly consists in applying such components as piping and wiring, controls, instruments, guns, hydraulic units, pilot seats, and landing gear elements. Wherever possible, as much of the work as can be done outside the fuselage is performed at benches or in special jigs here all tools and small parts needed are immediately at hand. The subassembly thus built up is then either placed in stock rooms along the line or is put in racks on the floor or balcony directly along the line where it is handiest to the assemblers who apply it to the fuselage. Stock boys keep the racks filled, hence assemblers rarely have to leave their stations to pick up parts or subassemblies which they must install. Because of the chance that assemblers may strike their heads against brackets or other projecting parts, those doing this work, especially in the bomb bay, wear fiber helmets for head protection.

Engines and the mounts which support them in the plane are received from outside suppliers and, before being placed in the plane, are combined with several accessories into an engine assembly, which is built up on a special wheeled dolly in a department assigned for this job. Engines are lifted. from crates by a hoist on a trolley rail and, after assembly to mounts and attachment of the latter to the dolly, the dollies progress along guide rails past bins and benches where the various parts and accessories are stored or prepared for attachment. By the time the assembly reaches the end of the line, it is ready for installation in the fuselage and is transferred to the fuselage line on a trolley hoist. This takes place just after the fuselage leaves the balconied area and emerges into the last of the high bays paralleling the balcony bays. While traversing this bay, considerable work at a high level has to be done, hence there are connected to the dolly wheeled scaffolds which advance with it and the fuselage while landing gear, engine, and other subassemblies are installed and inspected.

After the fuselage, still in the dolly, reaches the end of the last bay, mentioned above, it is disconnected from the floor chain. Thereafter it is pushed by hand on the wheeled dolly and is turned at right angles into the crane bay, along which it is advanced until completed. Wings and tail surfaces, received on truck-trailers from other plants, are unloaded into caster dollies at the end of this bay and the crane is used to transfer the wings from the dollies to the plane. Before the wings are installed, however, the tail surfaces are attached. This is done from castered scaffolds attached to the dolly and advanced with it through much of the crane bay.

Initially, wings were installed from a fixture having three jacks, but Eastern persuaded the Navy to make an engineering change on the wing to the extent of installing a threaded sleeve at the center of gravity. This makes it possible to insert an eyebolt by which the wing can be suspended from the crane. When so suspended, the wing is very easily shifted (guided by only one man, instead of three required before) and is attached at the hinges to the ends of the wing center section. After this has been done, considerable time is required in connecting the hydraulic parts for folding and unfolding the wings and in testing the system to insure its functioning as specified.

While adjustments are proceeding, the central gun turret is lowered into place by the crane, is attached to the fuselage, and readied for test. The Plexiglas enclosures for the turret and the cockpits are also put in place and are fastened.

When the plane assembly has progressed about half the length of the bay, wheels are put in place on the landing gear. The tail wheel has already been installed. This makes it possible for the dolly to be removed and for the plane to be advanced on its own wheels. But, to keep it level for test purposes, a small, high-wheeled dolly is placed under the tail. The large dolly, being at this point quite near the start of the line on which it is to be used again, is wheeled by hand back to the area beside the master assembly fixtures. In the meantime, the plane proceeds toward completion of assembly, and various hydraulic and electric tests are made.

At the final station on the assembly line and just before entering the final paint room, the plane reaches a darkened area of the bay and “targets” are applied to tail and other surfaces to check the machine gun and turret. These tests make sure that the guns and turret are so adjusted that fire from the gun cannot injure any part of the plane. This is done by attaching to the gun a small projecting device which throws a light beam against the targets along the paths of the weapons' fire.

Special care has been exercised in the design of the final painting room to assure the best possible working conditions. The room is really a short section of the crane bay but is walled off from the bay and is provided with large air-operated doors at both ends for planes to enter and leave. The room accommodates two planes at a time. All air entering the room is drawn through filters in the ceiling and is exhausted through floor trenches which carry water about a foot deep. The trenches are laid out to approximate the floor plan of the ship and are covered with grating through which the air, carrying fumes and pigment particles, is exhausted. Solid particles passing the gratings are mostly deposited on the surface of the water, from which they are easily removed and can be recovered, but any residue is caught in filters.

Down-draft through the room carries off excess paint spray rapidly and, although painters must wear masks, working conditions are excellent. When the plane is shifted into painting position, scaffolds on wheels are moved beside it, and some parts are masked. Upper portions of the ship are then sprayed and, after removing the scaffolds, the lower portions are sprayed. After drying and inspection, the ship is wheeled into the adjacent final inspection room, where radio and other electrical equipment undergo test and the ship is ready for transfer to the hangar for Navy flight tests.

This article was originally published in the July, 1943, issue of Aviation magazine, vol 42, no 7, pp 168-173, 326-327, 329.
The original article includes 12, mostly small, photos and a production flow diagram.
Photos are not credited.