Segment Information The Company operates in three principal segments: Fuselage Systems, Propulsion Systems, and Wing Systems. Revenue from Boeing represents a substantial portion of the Company's revenues in all segments. Wing Systems also includes significant revenues from Airbus. Approximately 89% of the Company's net revenues for the three months ended April 2, 2020 , came from the Company's two largest customers, Boeing and Airbus. All other activities fall within the All Other segment, principally made up of sundry sales of miscellaneous services, tooling contracts and sales of natural gas through a tenancy-in-common with other companies that have operations in Wichita, Kansas. The Company's primary profitability measure to review a segments operating performance is segment operating income before corporate selling, general and administrative expenses, research and development, and unallocated cost of sales. Corporate selling, general and administrative expenses include centralized functions such as accounting, treasury, and human resources that are not specifically related to the Company's operating segments and are not allocated in measuring the operating segments profitability and performance and net profit margins. Research and development includes research and development efforts that benefit the Company as a whole and are not unique to a specific segment. Restructuring costs represent corporate level charges related to involuntary workforce reductions and the VRP. Unallocated cost of sales includes general costs not directly attributable to segment operations, such as warranty, early retirement and other incentives. All of these items are not specifically related to the Companys operating segments and are not utilized in measuring the operating segments profitability and performance. The Companys Fuselage Systems segment includes development, production, and marketing of forward, mid and rear fuselage sections and systems, primarily to aircraft Original Equipment Manufacturers (OEMs), as well as related spares and maintenance, repairs and overhaul (MRO) services and exterior components of rocket systems. The Fuselage Systems segment manufactures products at the Company's facilities in Wichita, Kansas; Biddeford, Maine; Tulsa; Kinston, North Carolina; McAlester, Oklahoma; San Antonio, Texas; and Subang, Malaysia. The Fuselage Systems segment also includes an assembly plant for the A350 XWB aircraft in Saint-Nazaire, France. The Companys Propulsion Systems segment includes development, production and marketing of struts/pylons, nacelles (including thrust reversers), and related engine structural components primarily to aircraft or engine OEMs, as well as related spares and MRO services and internal components to rocket propulsion systems. The Propulsion Systems segment manufactures products at the Company's facility in Wichita, Kansas; Biddeford, Maine; and San Antonio, Texas. The Companys Wing Systems segment includes development, production and marketing of wings and wing components (including flight control surfaces), and other miscellaneous structural parts primarily to aircraft OEMs, as well as related spares and MRO services. These activities take place at the Companys facilities in Kinston, North Carolina; Tulsa and McAlester, Oklahoma; San Antonio, Texas; Prestwick, Scotland; and Subang, Malaysia. The Companys segments are consistent with the organization and responsibilities of management reporting to the chief operating decision-maker for the purpose of assessing performance. The Companys definition of segment operating income differs from net profit margin as presented in its primary financial statements and a reconciliation of the segment and consolidated results is provided in the table set forth below. While some working capital accounts are maintained on a segment basis, much of the Companys assets are not managed or maintained on a segment basis. Property, plant and equipment, including tooling, is used in the design and production of products for each of the segments and, therefore, is not allocated to any individual segment. In addition, cash, prepaid expenses, other assets and deferred taxes are managed and maintained on a consolidated basis and generally do not pertain to any particular segment. Raw materials and certain component parts are used in aerostructure production across all segments. Work-in-process inventory is identifiable by segment, but is managed and evaluated at the program level. As there is no segmentation of the Companys productive assets, depreciation expense (included in fixed manufacturing costs and selling, general and administrative expenses) and capital expenditures, no allocation of these amounts has been made solely for purposes of segment disclosure requirements. The following table shows segment revenues and operating income for the three months ended April 2, 2020 and March 28, 2019 : Three Months Ended April 2, 2020 March 28, 2019 Segment Revenues Fuselage Systems $ 551.5 $ 1,069.6 Propulsion Systems 225.2 485.7 Wing Systems 291.4 407.9 All Other 9.2 4.6 $ 1,077.3 $ 1,967.8 Segment Operating Income (Loss) Fuselage Systems (1) $ (86.4 ) $ 138.9 Propulsion Systems (2) (5.3 ) 95.5 Wing Systems (3) 13.6 65.8 All Other 1.8 1.2 (76.3 ) 301.4 SG&amp;A (77.4 ) (63.6 ) Research and development (12.3 ) (12.9 ) Unallocated cost of sales (1.5 ) 8.1 Total operating income $ (167.5 ) $ 233.0 (1) includes excess capacity cost of $51.2 related to the B737 MAX production schedule adjustment that began on January 1, 2020, $15.3 abnormal costs of temporary workforce adjustments resulting from the Boeing production suspension which began on March 25, 2020 related to COVID-19, and $30.1 restructuring costs. (2) includes excess capacity cost of $15.8 related to the B737 MAX production schedule adjustment that began on January 1, 2020, $6.2 abnormal costs of temporary workforce adjustments resulting from the Boeing production suspension which began on March 25, 2020 related to COVID-19, and $8.8 restructuring costs. (3) includes excess capacity cost of $6.4 related to the B737 MAX production schedule adjustment that began on January 1, 2020, $3.9 abnormal costs of temporary workforce adjustments resulting from the Boeing production suspension which began on March 25, 2020 related to COVID-19, and $3.7 restructuring costs.