TransDigm Inc. was formed in 1993 in connection with a leveraged buyout transaction. TD Group was formed in 2003 to facilitate a leveraged buyout of TransDigm Inc. The Company was owned by private equity funds until its initial public offering in 2006. TD Group’s common stock is publicly traded on the New York Stock Exchange, or NYSE, under the ticker symbol “TDG.”

We believe we are a leading global designer, producer and supplier of highly engineered aircraft components for use on nearly all commercial and military aircraft in service today. Our business is well diversified due to the broad range of products we offer to our customers. We estimate that about 90% of our net sales for fiscal year 20172018 were generated by proprietary products. In addition, for fiscal year 2017,2018, we estimate that we generated about 80% of our net sales from products for which we are the sole source provider.

Most of our products generate significant aftermarket revenue. Once our parts are designed into and sold on a new aircraft, we generate net sales from aftermarket consumption over the life of that aircraft, which is generally estimated to be approximately 25 to 30 years. A typical platform can be produced for 20 to 30 years, giving us an estimated product life cycle in excess of 50 years. We estimate that approximately 55%60% of our net sales in fiscal year 20172018 were generated from aftermarket sales, the vast majority of which come from the commercial and military aftermarkets. These aftermarket revenues have historically produced a higher gross margin and been more stable than sales to original equipment manufacturers, or OEMs.

We primarily design, produce and supply highly engineered proprietary aerospace components (and certain systems/subsystems) with significant aftermarket content. We seek to develop highly customized products to solve specific needs for aircraft operators and manufacturers. We attempt to differentiate ourselves based on engineering, service and manufacturing capabilities. We typically choose not to compete for non-proprietary “build to print” business because it frequently offers lower

Our business is well diversified due to the broad range of products that we offer to our customers. Some of our more significant product offerings, substantially all of which are ultimately provided to end-users in the aerospace industry, include mechanical/electro-mechanical actuators and controls, ignition systems and engine technology, specialized pumps and valves, power conditioning devices, specialized AC/DC electric motors and generators, NiCad batteries and chargers, engineered latching and locking devices, rods and locking devices, engineered connectors and elastomers, databus and power controls, cockpit security components and systems, specialized cockpit displays, aircraft audio systems, specialized lavatory components, seat belts and safety restraints, engineered interior surfaces and related components, lighting and control technology, military personnel parachutes, high performance hoists, winches and lifting devices, and cargo loading, handling and delivery systems.

The Company’s businesses are organized and managed in three reporting segments: Power & Control, Airframe and Non-aviation.

The Power & Control segment includes operations that primarily develop, produce and market systems and components that predominately provide power to or control power of the aircraft utilizing electronic, fluid, power and mechanical motion control technologies. Major product offerings include mechanical/electro-mechanical actuators and controls, ignition systems and engine technology, specialized pumps and valves, power conditioning devices, specialized AC/DC electric motors and generators, databus and power controls, high performance hoists, winches and lifting devices and cargo loading and handling systems. Primary customers of this segment are engine and power system and subsystem suppliers, airlines, third party maintenance suppliers, military buying agencies and repair depots. Products are sold in the OEM and aftermarket market channels.

The Airframe segment includes operations that primarily develop, produce and market systems and components that are used in non-power airframe applications utilizing airframe and cabin structure technologies. Major product offerings include engineered latching and locking devices, rods and locking devices, engineered connectors and elastomers, cockpit security components and systems, aircraft audio systems, specialized lavatory components, seat belts and safety restraints, engineered interior surfaces and related components, lighting and control technology, military personnel parachutes and cargo delivery systems. Primary customers of this segment are airframe manufacturers and cabin system suppliers and subsystem suppliers, airlines, third party maintenance suppliers, military buying agencies and repair depots. Products are sold in the OEM and aftermarket market channels.

The Non-aviation segment includes operations that primarily develop, produce and market products for non-aviation markets. Major product offerings include seat belts and safety restraints for ground transportation applications, mechanical/electro-mechanical actuators and controls for space applications, and refueling systems for heavy equipment used in mining, construction and other industries. Primary customers of this segment are off-road vehicle suppliers and subsystem suppliers, child restraint system suppliers, satellite and space system suppliers and manufacturers of heavy equipment used in mining, construction and other industries.

For financial information about our segments, see Note 16, “Segments,” to ourthe consolidated financial statements included herein.herein, which is incorporated by reference.

Consistent with our overall strategy, our sales and marketing organization is structured to continually develop technical solutions that meet customer needs. In particular, we attempt to focus on products and programs that will lead to high-margin, repeatable sales in the aftermarket.

We have structured our sales efforts along our major product offerings, assigning a business unit manager to certain products. Each business unit manager is expected to grow the sales and profitability of the products for which he or she is responsible and to achieve the targeted annual level of bookings, sales, new business and profitability for such products. The business unit managers are assisted by account managers and sales engineers who are responsible for covering major OEM and aftermarket accounts. Account managers and sales engineers are expected to be familiar with the personnel, organization and needs of specific customers to achieve total bookings and new business goals at each account and, together with the business unit managers, to determine when additional resources are required at customer locations. Most of our sales personnel are evaluated, in part, on their bookings and their ability to identify and obtain new business opportunities.

Though typically performed by employees, the account manager function may be performed by independent representatives depending on the specific customer, product and geographic location. We also use a number of distributors to provide logistical support as well as serve as a primary customer contact with certain smaller accounts. Our major distributors are Aviall, Inc. (a subsidiary of The Boeing Company) and Satair A/S (a subsidiary of Airbus S.A.S.).

We maintain approximately 60 principal80 manufacturing facilities. Most of our manufacturing facilities are comprised of manufacturing, distribution and engineering functions, and most facilities have certain administrative functions, including

We attempt to differentiate ourselves from our competitors by producing uniquely engineered products with high quality and timely delivery. Our engineering costs are recorded in cost of sales and in selling and administrative expenses and research and development costs are recorded in selling and administrative expenses in our consolidated statements of income. The aggregate of engineering expense and research and development expense represents approximately 8% of our operating units’ aggregate costs, or approximately 4% of our consolidated net sales.sales for fiscal year 2018. Our proprietary products, and particularly our new product initiatives, are designed by our engineers and are intended to serve the needs of the aircraft component industry. These proprietary designs must withstand the extraordinary conditions and stresses that will be endured by products during use and meet the rigorous demands of our customers’ tolerance and quality requirements.

We use sophisticated equipment and procedures to comply with quality requirements, specifications and Federal Aviation Administration (“FAA”) and OEM requirements. We perform a variety of testing procedures as required by our customers, such as testing under different temperature, humidity and altitude levels, flammability testing, shock and vibration testing and X-ray fluorescent measurement. These procedures, together with other customer approved techniques for document, process and quality control, are used throughout our manufacturing facilities. Refer to Note 3, “Summary of Significant Accounting Policies,” to the consolidated financial statements included herein with respect to total costs of research and development, which is incorporated herein by reference.

We predominantly serve customers in the commercial, regional, business jet and general aviation aftermarket, which accounts for approximately 35%36% of total sales; the commercial aerospace OEM market, comprising large commercial transport manufacturers and regional and business jet manufacturers, which accounts for approximately 26%24% of total sales; and the defense market, which accounts for approximately 34%35% of total sales. Non-aerospace sales comprise approximately 5% of our total sales.

Our customers include: (1) distributors of aerospace components; (2) worldwide commercial airlines, including national and regional airlines; (3) large commercial transport and regional and business aircraft OEMs; (4) various armed forces of the United States and friendly foreign governments; (5) defense OEMs; (6) system suppliers; and (7) various other industrial customers. For the year ended September 30, 2017,2018, Airbus S.A.S. (which includes Satair A/S, a distributor of commercial aftermarket parts to airlines throughout the world) accounted for approximately 13%11% of our net sales and The Boeing Company (which includes Aviall, Inc., also a distributor of commercial aftermarket parts to airlines throughout the world) accounted for approximately 11%10% of our net sales. Our top ten customers for fiscal year 20172018 accounted for approximately 46%43% of our net sales. Products supplied to many of our customers are used on multiple platforms.

Active commercial production programs include the Boeing 737 (including the 737MAX), 747, 767, 777 and 787, the Airbus A220 (previously known as the Bombardier CSeries), A320 family (including neo), A330, A350 and A380, the Bombardier CSeries, CRJ’s,CRJs, Q400/Dash-8 aircraft, Challenger and Learjets, the Embraer Regionalregional and business jets, the Cessna Citation family, the Gulfstream aircraft family, the Dassault aircraft family, the HondaJet and the ATR42/72 turboprop. Military platforms include aircraft such as the Boeing AH-64 Apache, CH-47, C17 Chinook,C-17, F-15, F-18, KC46 Tanker, P-8 and V-22, the Airbus A400M, the Lockheed Martin C-130J, F-16 and F-35 Joint Strike Fighter, UH-60 Blackhawk helicopter, the Northrop Grumman E-2C Hawkeye, the General

The markets in which we sell our products are, to varying degrees, cyclical and have experienced upswings and downturns. The demand for our commercial aftermarket parts and services depends on, among other things, the breadth of our installed OEM base, revenue passenger miles (“RPMs”), the size and age of the worldwide aircraft fleet, the percentage of the worldwide fleet that is in warranty, and airline profitability. The demand for defense products is specifically dependent on government budget trends, military campaigns and political pressures.

The niche markets within the aerospace industry that we serve are relatively fragmented and we face several competitors for many of the products and services we provide. Due to the global nature of the commercial aircraft industry, competition in these categories comes from both U.S. and foreign companies. Competitors in our product offerings range in size from divisions of large public corporations to small privately-held entities with only one or two components in their entire product portfolios.

We compete on the basis of engineering, manufacturing and marketing high quality products, which we believe meet or exceed the performance and maintenance requirements of our customers, consistent and timely delivery, and superior customer service and support. The industry’s stringent regulatory, certification and technical requirements and the investments necessary

Companies engaged in supplying defense-related equipment and services to U.S. Government agencies are subject to business risks specific to the defense industry. These risks include the ability of the U.S. Government to unilaterally: (1) suspend us from receiving new contracts and impose criminal penalties based on alleged violations of procurement laws or regulations;contracts; (2) terminate existing contracts; (3) reduce the value of existing contracts; (4) audit our contract-related costs and fees, including allocated indirect costs; (5) control and potentially prohibit the export of our products; and (6) seek repayment of contract related payments under certain circumstances. Violations of government procurement laws could result in civil or criminal penalties.

The commercial aircraft component industry is highly regulated by the FAA in the United States and by the Joint Aviation Authorities in Europe and other agencies throughout the world, while the military aircraft component industry is governed by military quality specifications. We, and the components we manufacture, are required to be certified by one or more of these entities or agencies, and, in many cases, by individual OEMs, in order to engineer and service parts and components used in specific aircraft models.

We must also satisfy the requirements of our customers, including OEMs and airlines that are subject to FAA regulations, and provide these customers with products and services that comply with the government regulations applicable to commercial flight operations. In addition, the FAA requires that various maintenance routines be performed on aircraft components. We believe that we currently satisfy or exceed these maintenance standards in our repair and overhaul services. We also maintain several FAA approved repair stations.

In addition, our businesses are subject to many other laws and requirements typically applicable to manufacturers and exporters. Without limiting the foregoing, sales of many of our products that will be used on aircraft owned by foreign entities are subject to compliance with export control laws and the manufacture of our products and the operations of our businesses, including the disposal of hazardous wastes, are subject to compliance with applicable environmental laws.

The commercial aerospace industry, including the aftermarket and OEM market, is impacted by the health of the global economy and geo-political events around the world. The commercial aerospace industry hadhas shown strength with increases in revenue passenger miles, or RPMs, between 2003 and 2008, as well as increases in OEM production and backlog. However, in 2009, the global economic downturn negatively impacted the commercial aerospace industry causing RPMs to decline slightly. This market sector began to rebound insince 2010, and positive growth has continued through 20172018 with increases in RPMs, as well as the growth in the large commercial OEM sector (aircraft with 100 or more seats) with order announcements by The Boeing Company and Airbus S.A.S. leading to planned increases in production. The 20182019 leading indicators and industry consensus suggest a continuation of current trends in the commercial transport market sector supported by continued RPM growth and increases in production at the OEM level.

The defense aerospace market is dependent on government budget constraints, the timing of orders, political pressures and the extent of global conflicts. It is not necessarily affected by general economic conditions that affect the commercial aerospace industry.

Our presence in both the commercial aerospace and military sectors of the aerospace industry may mitigate the impact on our business of any specific industry risk. We service a diversified customer base in the commercial and military aerospace industry, and we provide components to a diverse installed base of aircraft, which mitigates our exposure to any individual airframe platform. At times, declines in sales in one channel have been offset by increased sales in another.another channel. However, due to differences between the profitability of our products sold to OEM and aftermarket customers, variation in product mix can cause variation in gross margin.

There are many short-term factors (including inventory corrections, unannounced changes in order patterns, strikes and mergers and acquisitions) that can cause short-term disruptions in our quarterly shipment patterns as compared to previous quarters and the same periods in prior years. As such, it can be difficult to determine longer-term trends in our business based on quarterly comparisons. To normalize for short-term fluctuations, we tend to look at our performance over several quarters or years of activity rather than discrete short-term periods.

There are also fluctuations in OEM and aftermarket ordering and delivery requests from quarter-to-quarter, as well as variations in product mix from quarter-to-quarter, that may cause positive or negative variations in gross profit margins since

The key growth factors in the commercial aftermarket include worldwide RPMs and the size and activity level of the worldwide fleet of aircraft and the percentage of the fleet that is in warranty.

The commercial transport market sector, the largest sector in the commercial OEM market, grew modestly during 2017.2018. Our commercial transport OEM shipments and revenues generally run ahead of the Boeing and Airbus airframe delivery schedules. As a result and consistent with prior years, our fiscal 20182019 shipments will be a function of, among other things, the estimated 20182019 and 20192020 commercial airframe production rates. We have been experiencing increased sales in the large commercial OEM sector (aircraft with 100 or more seats) driven by an increase in production by The Boeing Company and Airbus S.A.S tied to previous order announcements. Industry consensus indicates this production increase will continue in 20182019 and 2019,2020, though the growth may continue to moderate and begin to flatten.

Our military business fluctuates from year to year, and is dependent, to a degree, on government budget constraints, the timing of orders and the extent of global conflicts. For a variety of reasons, the military spending outlook is very uncertain. For planning purposes we assume that military related sales of our types of products to be flat in future years over the recent high levels.

We require the use of various raw materials in our manufacturing processes. We also purchase a variety of manufactured component parts from various suppliers. At times, we concentrate our orders among a few suppliers in order to strengthen our supplier relationships. Most of our raw materials and component parts are generally available from multiple suppliers at competitive prices.

We have various trade secrets, proprietary information, trademarks, trade names, patents, copyrights and other intellectual property rights, which we believe, in the aggregate but not individually, are important to our business.

As of September 30, 2017,2018, the Company estimated its sales order backlog at $1,669$2,026 million compared to an estimated sales order backlog of $1,554$1,669 million as of September 30, 2016.2017. The increase in estimated sales order backlog is primarily due to organic growth in the commercial and defense markets and growth from acquisitions. The majority of the purchase orders outstanding as of September 30, 20172018 are scheduled for delivery within the next twelve months. Purchase orders may be subject to cancellation or deferral by the customer prior to shipment. The level of unfilled purchase orders at any given date during the year will be materially affected by the timing of the Company’s receipt of purchase orders and the speed with which those orders are filled. Accordingly, the Company’s backlog as of September 30, 20172018 may not necessarily represent the actual amount of shipments or sales for any future period.

Although we manufacture a significant portion of our products in the United States, we manufacture some products in Belgium, China, Germany, Hungary, Japan, Malaysia, Mexico, Norway, Sri Lanka, Sweden and the United Kingdom. Although the majority of sales of our products are made to customers (including distributors) located in the United States, our products are ultimately sold to and used by customers (including airlines and other end users of aircraft) throughout the world. A number of risks inherent in international operations could have a material adverse effect on our results of operations, including currency fluctuations, difficulties in staffing and managing multi-national operations, general economic and political uncertainties and potential for social unrest in countries in which we operate, limitations on our ability to enforce legal rights and remedies, restrictions on the repatriation of funds, change in trade policies, tariff regulation, difficulties in obtaining export and import licenses and the risk of government financed competition.

Our operations and facilities are subject to a number of federal, state, local and foreign environmental laws and regulations that govern, among other things, discharges of pollutants into the air and water, the generation, handling, storage and disposal of hazardous materials and wastes, the remediation of contamination and the health and safety of our employees. Environmental laws and regulations may require that the Company investigate and remediate the effects of the release or disposal of materials at sites associated with past and present operations. Certain facilities and third-party sites utilized by the Company have been identified

As of September 30, 2017,2018, we had approximately 9,20010,100 full-time, part-time and temporary employees. Approximately 11%10% of our full-time and part-time employees were represented by labor unions. Collective bargaining agreements between us and these labor unions expire at various dates ranging from FebruaryDecember 2018 to November 2020.May 2022. We consider our relationship with our employees generally to be satisfactory.

Our commercial business is directly affected by, among other factors, changes in revenue passenger miles (RPMs), the size and age of the worldwide aircraft fleet, the percentage of the fleet that is out-of-warranty and changes in the profitability of the commercial airline industry. RPMs and airline profitability have historically been correlated with the general economic environment, although national and international events also play a key role. For example, in the past, the airline industry has been severely affected by the downturn in the global economy, higher fuel prices, the increased security concerns among airline customers following the events of September 11, 2001, the Severe Acute Respiratory Syndrome (SARS) epidemic, and the conflicts abroad, and could be impacted by future geopolitical or other worldwide events, such as war, terrorist acts, or a worldwide infectious disease outbreak. In addition, global market and economic conditions have been challenging with turbulence in the U.S. and international markets and economies and have prolonged declines in business and consumer spending. As a result of the substantial reduction in airline traffic resulting from these events, the airline industry incurred large losses and financial difficulties. Some carriers have also parked or retired a portion of their fleets and have reduced workforces and flights. During periods of reduced airline profitability, some airlines may delay purchases of spare parts, preferring instead to deplete existing inventories, and delay refurbishments and discretionary spending. If demand for spare parts decreases, there would be a decrease in demand for certain of our products. An adverse change in demand could impact our results of operations, collection of accounts receivable and our

Our sales to manufacturers of large commercial aircraft, such as The Boeing Company, Airbus S.A.S, and related OEM suppliers, as well as manufacturers of business jets (which collectively accounted for approximately 25%24% of our net sales in fiscal year 2017)2018) have historically experienced periodic downturns. In the past, these sales have been affected by airline profitability, which is impacted by, among other things, fuel and labor costs, price competition, interest rates, downturns in the global economy and national and international events. In addition, sales of our products to manufacturers of business jets are impacted by, among other things, downturns in the global economy. Downturns adversely affect our net sales, gross margin and net income.

Our two largest customers for fiscal year 20172018 were Airbus S.A.S. (which includes Satair A/S) and The Boeing Company (which includes Aviall, Inc.). Airbus S.A.S. accounted for approximately13%approximately 11% of our net sales and The Boeing Company accounted for approximately 11%10% of our net sales in fiscal year 2017.2018. Our top ten customers for fiscal year 20172018 accounted for approximately 46%43% of our net sales. A material reduction in purchasing by one of our larger customers for any reason, including but not limited to economic downturn, decreased production, strike or resourcing, could have a material adverse effect on our net sales, gross margin and net income.

As is customary in our business, we do not generally have long-term contracts with most of our aftermarket customers and, therefore, do not have guaranteed future sales. Although we have long-term contracts with many of our OEM customers, many of those customers may terminate the contracts on short notice and, in most cases, our customers have not committed to buy any minimum quantity of our products. In addition, in certain cases, we must anticipate the future volume of orders based upon the historic purchasing patterns of customers and upon our discussions with customers as to their anticipated future requirements, and this anticipated future volume of orders may not materialize.

We also have entered into multi-year, fixed-price contracts with some of our customers, pursuant to which we have agreed to perform the work for a fixed price and, accordingly, realize all the benefit or detriment resulting from any decreases or increases in the costs of making these products. Sometimes we accept a fixed-price contract for a product that we have not yet produced, and this increases the risk of cost overruns or delays in the completion of the design and manufacturing of the product. Most of our contracts do not permit us to recover increases in raw material prices, taxes or labor costs.

The military and defense market is significantly dependent upon government budget trends, particularly the U.S. Department of Defense (the “DOD”) budget. In addition to normal business risks, our supply of products to the United States Government is subject to unique risks largely beyond our control. DOD budgets could be negatively impacted by several factors, including, but not limited to, a change in defense spending policy by the current presidential administration, the U.S. Government’s budget deficits, spending priorities, the cost of sustaining the U.S. military presence internationally and possible political pressure to reduce U.S. Government military spending, each of which could cause the DOD budget to remain unchanged or to decline. A significant decline in U.S. military expenditures could result in a reduction in the amount of our products sold to the various agencies and buying organizations of the U.S. Government.

A significant portion of our growth has occurred through acquisitions. Any future growth through acquisitions will be partially dependent upon the continued availability of suitable acquisition candidates at favorable prices and upon advantageous terms and conditions. We intend to pursue acquisitions that we believe will present opportunities consistent with our overall business strategy. However, we may not be able to find suitable acquisition candidates to purchase or may be unable to acquire desired businesses or assets on economically acceptable terms or may be unable to receive necessary regulatory approvals or support. In addition, we may not be able to raise the capital necessary to fund future acquisitions. Because we may actively pursue a number of opportunities simultaneously, we may encounter unforeseen expenses, complications and delays, including regulatory complications or difficulties in employing sufficient staff and maintaining operational and management oversight.

We regularly engage in discussions with respect to potential acquisition and investment opportunities. If we consummate an acquisition, our capitalization and results of operations may change significantly. Future acquisitions could result in margin dilution and further likely result in the incurrence of additional debt and contingent liabilities and an increase in interest and

Acquisitions involve risks that the businesses acquired will not perform in accordance with expectations and that business judgments concerning the value, strengths and weaknesses of businesses acquired will prove incorrect. In addition, we may not be able to successfully integrate any business we acquire into our existing business. The successful integration of new businesses depends on our ability to manage these new businesses and cut excess costs. The successful integration of future acquisitions may also require substantial attention from our senior management and the management of the acquired business, which could decrease the time that they have to service, attract customers and develop new products and services or attend to other acquisition opportunities.

We are subject to many of the foregoing risks in connection with our recently announced agreement to acquire Esterline, and these risks may be exacerbated due to the scale and complexity of that acquisition as compared to our recent acquisitions.  The acquisition is not expected to close until 2019, subject to approval of Esterline’s shareholders, as well as other customary closing conditions, including the receipt of required regulatory approvals, so there can be no assurance that we will not encounter unforeseen expenses, complications and delays in the process or that we will be able to consummate the acquisition as contemplated or at all.  If the acquisition is completed, it will require extensive integration efforts.  These efforts could result in significant unforeseen costs and will require substantial attention from our senior management.  If we are unable to successfully integrate Esterline or the acquisition otherwise does not perform to our expectations, our results of operations and financial condition may be adversely affected.  It is also possible that the substantial management attention required by, and the indebtedness to be incurred in connection with, the transaction could cause us to forgo other acquisition opportunities, particularly if we encounter delays or unexpected costs or the acquisition otherwise does not perform to our expectations.

Companies engaged in supplying defense-related equipment and services to U.S. Government agencies are subject to business risks specific to the defense industry. These risks include the ability of the U.S. Government to unilaterally:

Most of our U.S. Government contracts can be terminated by the U.S. Government for its convenience without significant notice. Termination for convenience provisions provide only for our recovery of costs incurred or committed, settlement expenses and profit on the work completed prior to termination.

On contracts for which the price is based on cost, the U.S. Government may review our costs and performance, as well as our accounting and general business practices. Based on the results of such audits, the U.S. Government may adjust our contract-related costs and fees, including allocated indirect costs. In addition, under U.S. Government purchasing regulations, some of our costs, including most financing costs, amortization of intangible assets, portions of research and development costs, and certain marketing expenses may not be subject to reimbursement.

Furthermore, even where the price is not based on cost, the U.S. Government may seek to review our costs to determine whether our pricing is “fair and reasonable.” Our subsidiaries are periodically subject to a pricing review and in fact, government buying agencies that purchase some of our subsidiaries’ products are currently the subject of a DOD Office of Inspector General audit with respect to prices paid for such products. Pricing reviews and government audits, including the one underway, could be costly and time consuming for our management and could distract from our ability to effectively manage the business. As a result of such a review, we could be subject to providing a refund to the U.S. Government or we could be asked to enter into an arrangement whereby our prices would be based on cost or the DOD could seek to pursue alternative sources of supply for our parts. Any of those occurrences could lead to a reduction in our revenue from, or the profitability of certain of our supply arrangements with, certain agencies and buying organizations of the U.S. Government.

Moreover, U.S. Government purchasing regulations contain a number of additional operationoperational requirements, which do not apply to entities not engaged in government contracting. Failure to comply with such government contracting requirements could result in civil and criminal penalties that could have a material adverse effect on the Company’s results of operations.

The aerospace industry is highly regulated in the United States and in other countries. In order to sell our components, we and the components we manufacture must be certified by the FAA, the DOD and similar agencies in foreign countries and by individual manufacturers. If new and more stringent government regulations are adopted or if industry oversight increases, we

In addition to the aviation approvals, we are at times required to obtain approval from U.S. Government agencies to export our products. Failure to obtain approval to export or determination by the U.S. Government that we failed to receive required approvals or licenses could eliminate or restrict our ability to sell our products outside the United States, and the penalties that could be imposed by the U.S. Government for failure to comply with these laws could be significant.

We have a significant amount of indebtedness. As of September 30, 2017,2018, our total indebtedness, excluding approximately $16$17.5 million of letters of credit outstanding, was approximately $11.8$12.9 billion, which was 133.5%116.3% of our total book capitalization as a result of our prior year special dividends being funded, in part, with indebtedness and the addition of approximately $1.6$1.1 billion in net new incremental borrowings during fiscal 2017.2018.

In addition, we may be able to incur substantial additional indebtedness in the future. For example, as of September 30, 2017,2018, we had approximately $584$582.5 million of unused commitments under our revolving loan facility. Although our senior secured credit facility and the indentures governing the various senior subordinated notes outstanding (the “Indentures”) contain restrictions on the incurrence of additional indebtedness, these restrictions are subject to a number of significant qualifications and exceptions, and the indebtedness incurred in compliance with these qualifications and exceptions could be substantial. For example, if the usage of the revolving loan facility exceeds 25% of the total revolving commitments, the Company will be required to maintain a maximum consolidated net leverage ratio of net debt, as defined, to trailing four-quarter EBITDA As Defined. A breach of any of the covenants or an inability to comply with the required leverage ratio could result in a default under the senior secured credit facility or the Indentures.

OurAn increase in our substantial debtindebtedness could also have other important consequences to investors. For example, it could:

In addition, all of our debt under the senior secured credit facility, which includes $7.0$7.6 billion in term loans and a revolving loan facility of $600 million, bears interest at floatingvariable rates. Accordingly, if interest rates increase, our debt service expense will also increase. Interest rate swap and cap agreements are used to manage interest rate risk associated with floating-ratevariable rate borrowings under our credit facilities. For information about our interest rate swap and cap agreements, see Note 20, “Derivatives and Hedging Instruments,” in the notes to the consolidated financial statements included herein.

Our substantial level of indebtedness increases the possibility that we may be unable to generate cash sufficient to pay, when due, the principal of, interest on or other amounts due in respect of our indebtedness, including the Indentures. We cannot assure that our business will generate sufficient cash flow from operations or that future borrowings will be available to us under the senior secured credit facility or otherwise in amounts sufficient to enable us to service our indebtedness. If we cannot service our debt, we will have to take actions such as reducing or delaying capital investments, selling assets, restructuring or refinancing our debt or seeking additional equity capital.

Our ability to make payments on and to refinance our indebtedness, including the Indentures, amounts borrowed under the senior secured credit facility, amounts due under our Securitization Facility, and to fund our operations, will depend on our ability

We cannot assure that our business will generate sufficient cash flow from operations, that currently anticipated cost savings and operating improvements will be realized on schedule, or at all, or that future borrowings will be available to us under the senior secured credit facility or otherwise in amounts sufficient to enable us to service our indebtedness, including the amounts borrowed under the senior secured credit facility, amounts borrowed under our Securitization Facility and the Indentures, or to fund our other liquidity needs. If we cannot service our debt, we will have to take actions such as reducing or delaying capital investments, selling assets, restructuring or refinancing our debt or seeking additional equity capital. We cannot assure that any of these remedies could, if necessary, be effected on commercially reasonable terms, or at all. Our ability to restructure or refinance our debt will depend on the condition of the capital markets and our financial condition at such time. Any refinancing of our debt could be at higher interest rates and may require us to comply with more onerous covenants, which could further restrict our business operations. The terms of existing or future debt instruments, the Securitization Facility, the Indentures and the senior secured credit facility may restrict us from adopting any of these alternatives. In addition, any failure to make payments of interest and principal on our outstanding indebtedness on a timely basis would likely result in a reduction of our credit rating, which could harm our ability to incur additional indebtedness on acceptable terms and would otherwise adversely affect the Indentures.

Our senior secured credit facility and the Indentures contain a number of restrictive covenants that impose significant operating and financial restrictions on TD Group, TransDigm Inc. and its subsidiaries (in the case of the senior secured credit facility) and TransDigm Inc. and its subsidiaries (in the case of the Indentures) and may limit their ability to engage in acts that may be in our long-term best interests. The senior secured credit facility and Indentures include covenants restricting, among other things, the ability of TD Group, TransDigm Inc. and its subsidiaries (in the case of the senior secured credit facility) and TransDigm Inc. and its subsidiaries (in the case of the Indentures) to:

A breach of any of these covenants could result in a default under the senior secured credit facility or the Indentures. If any such default occurs, the lenders under the senior secured credit facility and the holders of the senior subordinated notes may elect to declare all outstanding borrowings, together with accrued interest and other amounts payable thereunder, to be immediately due and payable. The lenders under the senior secured credit facility also have the right in these circumstances to terminate any commitments they have to provide further borrowings. In addition, following an event of default under the senior secured credit facility, the lenders under that facility will have the right to proceed against the collateral granted to them to secure the debt, which includes our available cash, and they will also have the right to prevent us from making debt service payments on the senior subordinated notes. If the debt under the senior secured credit facility or the senior subordinated notes were to be accelerated, we cannot assure that our assets would be sufficient to repay in full our debt.

Our operations and facilities are subject to a number of federal, state, local and foreign environmental laws and regulations that govern, among other things, discharges of pollutants into the air and water, the generation, handling, storage and disposal of hazardous materials and wastes, the remediation of contamination and the health and safety of our employees. Environmental laws and regulations may require that the Company investigate and remediate the effects of the release or disposal of materials at sites associated with past and present operations. Certain facilities and third-party sites utilized by subsidiaries of the Company have been identified as potentially responsible parties under the federal superfund laws and comparable state laws. The Company is currently involved in the investigation and remediation of a number of sites under applicable laws.

Estimates of the Company’s environmental liabilities are based on current facts, laws, regulations and technology. These estimates take into consideration the Company’s prior experience and professional judgment of the Company’s environmental advisors. Estimates of the Company’s environmental liabilities are further subject to uncertainties regarding the nature and extent of site contamination, the range of remediation alternatives available, evolving remediation standards, imprecise engineering evaluations and cost estimates, the extent of corrective actions that may be required and the number and financial condition of other potentially responsible parties, as well as the extent of their responsibility for the remediation.

Accordingly, as investigation and remediation proceed, it is likely that adjustments in the Company’s accruals will be necessary to reflect new information. The amounts of any such adjustments could have a material adverse effect on the Company’s results of operations or cash flows in a given period. Based on currently available information, however, the Company does not believe that future environmental costs in excess of those accrued with respect to sites for which the Company has been identified as a potentially responsible party are likely to have a material adverse effect on the Company’s financial condition.

Because our products are complicated and highly engineered, we depend on an educated and trained workforce. There is substantial competition for skilled personnel in the aircraft component industry, and we could be adversely affected by a shortage of skilled employees. We may not be able to fill new positions or vacancies created by expansion or turnover or attract and retain qualified personnel.

Although we believe that our relations with our employees are satisfactory, we cannot assure that we will be able to negotiate a satisfactory renewal of collective bargaining agreements or that our employee relations will remain stable. Because we maintain a relatively small inventory of finished goods, any work stoppage could materially and adversely affect our ability to provide products to our customers.

Our business is affected by the price and availability of the raw materials and component parts that we use to manufacture our components. Our business, therefore, could be adversely impacted by factors affecting our suppliers (such as the destruction of our suppliers’ facilities or their distribution infrastructure, a work stoppage or strike by our suppliers’ employees or the failure

A number of our manufacturing facilities are located in the greater Los Angeles area, an area known for earthquakes, and are thus vulnerable to damage. In addition, a number of our manufacturing facilities are located along the Eastern seaboard area susceptible to hurricanes. We are also vulnerable to damage from other types of disasters, including power loss, fire, explosions, floods, communications failures, terrorist attacks and similar events. Disruptions could also occur due to cyber-attacks, computer or equipment malfunction (accidental or intentional), operator error or process failures. Any disruption of our ability to operate our business could result in a material decrease in our revenues or significant additional costs to replace, repair or insure our assets, which could have a material adverse impact on our financial condition and results of operations.

A number of risks inherent in international operations could have a material adverse effect on our results of operations, including currency fluctuations, difficulties in staffing and managing multi-national operations, general economic and political uncertainties and potential for social unrest in countries in which we operate, limitations on our ability to enforce legal rights and remedies, restrictions on the repatriation of funds, change in trade policies, tariff regulation, difficulties in obtaining export and import licenses and the risk of government financed competition. Furthermore, the Company is subject to laws and regulations, such as the Foreign Corrupt Practices Act, UK Bribery Act and similar local anti-bribery laws, which generally prohibit companies and their employees, agents and contractors from making improper payments for the purpose of obtaining or retaining business. Failure to comply with these laws could subject the Company to civil and criminal penalties that could materially adversely affect the Company’s results of operations.

We operate in a highly competitive global industry and compete against a number of companies. Competitors in our product lines are both U.S. and foreign companies and range in size from divisions of large public corporations to small privately held entities. We believe that our ability to compete depends on high product performance, consistent high quality, short lead-time and timely delivery, competitive pricing, superior customer service and support and continued certification under customer quality requirements and assurance programs. We may have to adjust the prices of some of our products to stay competitive.

Our operations expose us to potential liabilities for personal injury or death as a result of the failure of an aircraft component that we have designed, manufactured or serviced. While we maintain liability insurance to protect us from future product liability claims, in the event of product liability claims our insurers may attempt to deny coverage or any coverage we have may not be adequate. We also may not be able to maintain insurance coverage in the future at an acceptable cost. Any liability not covered by insurance or for which third party indemnification is not available could result in significant liability to us.

In addition, a crash caused by one of our components could damage our reputation for quality products. We believe our customers consider safety and reliability as key criteria in selecting a provider of aircraft components. If a crash were to be caused by one of our components, or if we were to otherwise fail to maintain a satisfactory record of safety and reliability, our ability to retain and attract customers may be materially adversely affected.

Mergers and acquisitions have resulted in significant increases in identifiable intangible assets and goodwill. Identifiable intangible assets, which primarily include trademarks, trade names, trade secrets, and technology, were approximately $1.7$1.8 billion at September 30, 2017,2018, representing approximately 17%15% of our total assets. Goodwill recognized in accounting for the mergers and acquisitions was approximately $5.7$6.2 billion at September 30, 2017,2018, representing approximately 58%51% of our total assets. We may never realize the full value of our identifiable intangible assets and goodwill, and to the extent we were to determine that our identifiable intangible assets or our goodwill were impaired within the meaning of applicable accounting standards, we would be required to write-off the amount of any impairment.

We may sell additional shares of common stock into the public markets or issue convertible debt securities to raise capital in the future. The market price of our common stock could decline as a result of sales of a large number of shares of our common stock in the public markets or the perception that these sales could occur. These sales, or the possibility that these sales may occur, also might make it more difficult for us to sell equity securities to raise capital at a time and price that we deem appropriate.

Provisions in our amended and restated certificate of incorporation and bylaws may discourage, delay or prevent a merger or acquisition involving us that our stockholders may consider favorable. For example, our amended and restated certificate of incorporation authorizes our Board of Directors to issue up to 149,600,000 shares of “blank check” preferred stock. Without stockholder approval, the Board of Directors has the authority to attach special rights, including voting and dividend rights, to this preferred stock. With these rights, holders of preferred stock could make it more difficult for a third party to acquire us. Our amended and restated certificate of incorporation also provides that the affirmative vote of the holders of at least 75% of the voting power of our issued and outstanding capital stock, voting together as a single class, is required for the alteration, amendment or repeal of certain provisions of our amended and restated certificate of incorporation and certain provisions of our amended and restated bylaws, including the provisions relating to our stockholders’ ability to call special meetings, notice provisions for stockholder business to be conducted at an annual meeting, requests for stockholder lists and corporate records, nomination and removal of directors, and filling of vacancies on our Board of Directors.

We are also subject to the anti-takeover provisions of Section 203 of the Delaware General Corporation Law. Under these provisions, if anyone becomes an “interested stockholder,” we may not enter into a “business combination” with that person for three years without special approval, which could discourage a third party from making a takeover offer and could delay or prevent a change of control. For purposes of Section 203, “interested stockholder” means, generally, someone owning 15% or more of our outstanding voting stock or an affiliate of ours that owned 15% or more of our outstanding voting stock during the past three years, subject to certain exceptions as described in Section 203.

On July 3, 2013, June 4, 2014, October 14, 2016 and August 23, 2017, the Company’s Board of Directors authorized and declared special cash dividends of $22.00, $25.00, $24.00 and $22.00, respectively, on each outstanding share of common stock and cash dividend equivalent payments to holders of options under its stock option plans.

The Brea, Liberty, Kent, Union Gap, Bohemia, Addison, and 47,000 square feet Rancho Cucamonga property isproperties are subject to mortgage liens under our senior secured credit facility.

TransDigm’s principal leased properties (defined as greater than 10,000 square feet or related to a principal operation) as of September 30, 20172018 are as follows:

Our common stock is traded on the New York Stock Exchange, or NYSE, under the ticker symbol “TDG.” The following chart sets forth, for the periods indicated, the high and low sales prices of the common stock on the NYSE.

On November 3, 2017,2, 2018, there were 3035 stockholders of record of our common stock. We estimate that there were approximately 62,00070,000 beneficial stockholders, as of November 3, 2017, which includes an estimated amount of stockholders who have their shares held in their accounts by banks and brokers.

On October 14, 2016,During fiscal 2017, TD Group’s Board of Directors authorized and declared a special cash dividenddividends of $24.00 (in October 2016) and $22.00 (in August 2017) on each outstanding share of common stock and cash dividend equivalent payments under options granted under its stock optionincentive plans. The record date for the special dividend was October 24, 2016, and the payment date for the dividend was November 1, 2016. On August 23, 2017, TD Group’s Board of Directors authorized and declared a special cash dividend of $22.00 on each outstanding share of common stock and cash dividend equivalent payments under options granted under its stock option plans. The record date for the special dividend was September 5, 2017, and the payment date for the dividend was September 12, 2017. No dividends were declared induring fiscal 2015 or fiscal 2016.2018.

We do not anticipate declaring regular quarterly or annual cash dividends on our common stock in the near future. Any declaration of special cash dividends on our common stock in the future will be at the discretion of our Board of Directors and will depend upon our results of operations, earnings, capital requirements, financial condition, future prospects, contractual restrictions under the senior secured credit facility and Indentures, the availability of surplus under Delaware law and other factors deemed relevant by our Board of Directors. TD Group is a holding company and conducts all of its operations through direct and indirect subsidiaries. Unless TD Group receives dividends, distributions, advances, transfers of funds or other payments from our subsidiaries, TD Group will be unable to pay any dividends on our common stock in the future. The ability of any subsidiaries to take any of the foregoing actions is limited by the terms of our senior secured credit facility and Indentures and may be limited by future debt or other agreements that we may enter into.

Set forth below is a line graph comparing the cumulative total return of a hypothetical investment in the shares of common stock of TD Group with the cumulative total return of a hypothetical investment in each of the S&P 500 Index (“S&P 500”) and the S&P MidCap 400 S&P Aerospace & Defense Index based on the respective market prices of each such investment on the dates shown below, assuming an initial investment of $100 on September 30, 2012.2013.

The following table sets forth selected historical consolidated financial and other data of TD Group for the fiscal years ended September 30, 20132014 to 2017,2018, which have been derived from TD Group’s audited consolidated financial statements.

Separate historical financial information of TransDigm Inc. is not presented since the 5.50% Senior Subordinated Notes issued in October 2012 (the “2020 Notes”), the 6.00% Senior Subordinated Notes issued in June 2014 (the “2022 Notes”), the 6.50% Senior Subordinated Notes issued June 2014 (the “2024 Notes”), the 6.50% Senior Subordinated Notes issued May 2015 (the “2025 Notes”) and the 6.375% Senior Subordinated Notes issued June 2016 (the “2026“6.375% 2026 Notes”) (also together with the 2020 Notes, the 2022 Notes, the 2024 Notes, the 2025 Notes, and the 2026 Notes, the “Notes”) are fully and unconditionally guaranteed on a senior subordinated basis by TD Group, TransDigm UK and all direct and indirect domestic restricted subsidiaries of TransDigm Inc.’s Domestic Restricted Subsidiaries and sincebecause TD Group has no significant operations or significant assets separate from its investment in TransDigm Inc.

All of the acquisitions were accounted for using the acquisition method. The results of operations of the acquired businesses and product lines are included in TD Group’s consolidated financial statements from the effective date of each acquisition. During the fourth quarter of 2017, the Company committed to disposing of Schroth in

In connection with the settlement of a Department of Justice investigation into the competitive effects of the acquisition.acquisition, during the fourth quarter of 2017, the Company committed to dispose of the Schroth business.  Therefore, Schroth was classified as held-for-sale andbeginning in the fourth quarter of fiscal 2017. The results of operations of Schroth are reflected as discontinued operations asin the accompanying consolidated financial statements. On January 26, 2018, the Company completed the sale of September 30, 2017.

The information presented below should be read together with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the consolidated financial statements and accompanying notes included elsewhere herein.

We present below certain financial information based on our EBITDA and EBITDA As Defined. References to “EBITDA” mean earnings before interest, taxes, depreciation and amortization, and references to “EBITDA As Defined” mean EBITDA plus, as applicable for each relevant period, certain adjustments as set forth in the reconciliations of net income to EBITDA and EBITDA As Defined and the reconciliations of net cash provided by operating activities to EBITDA and EBITDA As Defined presented below.

Neither EBITDA nor EBITDA As Defined is a measurement of financial performance under accounting principles generally accepted in the United States of America (“GAAP”). We present EBITDA and EBITDA As Defined because we believe they are useful indicators for evaluating operating performance and liquidity.

Our management believes that EBITDA and EBITDA As Defined are useful as indicators of liquidity because securities analysts, investors, rating agencies and others use EBITDA to evaluate a company’s ability to incur and service debt. In addition, EBITDA As Defined is useful to investors because the revolving commitments under our senior secured credit facility requires compliance under certain circumstances, on a pro forma basis, with a financial covenant that measures the ratio of the amount of our secured indebtedness to the amount of our Consolidated EBITDA defined in the same manner as we define EBITDA As Defined herein.

In addition to the above, our management uses EBITDA As Defined to review and assess the performance of the management team in connection with employee incentive programs and to prepare its annual budget and financial projections. Moreover, our management uses EBITDA As Defined to evaluate acquisitions.

Although we use EBITDA and EBITDA As Defined as measures to assess the performance of our business and for the other purposes set forth above, the use of these non-GAAP financial measures as analytical tools has limitations, and you should not consider any of them in isolation, or as a substitute for analysis of our results of operations as reported in accordance with GAAP. Some of these limitations are:

Because of these limitations, EBITDA and EBITDA As Defined should not be considered as measures of discretionary cash available to us to invest in the growth of our business. Management compensates for these limitations by not viewing EBITDA or EBITDA As Defined in isolation and specifically by using other GAAP measures, such as net income, net sales and operating profit, to measure our operating performance. Neither EBITDA nor EBITDA As Defined is a measurement of financial performance under GAAP, and neither should be considered as an alternative to net income or cash flow from operations determined in accordance with GAAP. Our calculation of EBITDA and EBITDA As Defined may not be comparable to the calculation of similarly titled measures reported by other companies.

The following table sets forth a reconciliation of net income to EBITDA and EBITDA As Defined:

For fiscal year 2017,2018, we generated net sales of $3,504.3$3,811.1 million, gross profit of $1,984.6$2,177.5 million or 56.6%57.1% of sales, and net income of $596.9$957.1 million. We believe we have achieved steady, long-term growth in sales and improvements in operating performance since our formation in 1993 due to our competitive strengths and through execution of our value-driven operating strategy. More specifically, focusing our businesses on our value-driven operating strategy of obtaining profitable new business, carefully controlling the cost structure and pricing our highly engineered value-added products to fairly reflect the value we provide and the resources required to do so has historically resulted in improvements in gross profit and income from operations over the long term.

Our selective acquisition strategy has also contributed to the growth of our business. The integration of certain acquisitions into our existing businesses combined with implementing our proven operating strategy has historically resulted in improvements of the financial performance of the acquired business.

We believe our key competitive strengths include:

Acquisitions and the divestiture during the previousmost recent three fiscal years are more fully described in Note 2, “Acquisitions and Divestitures,” in the notes to the consolidated financial statements included herein.

Our consolidated financial statements have been prepared in conformity with GAAP, which often requires the judgment of management in the selection and application of certain accounting principles and methods. Management believes that the quality and reasonableness of our most critical policies enable the fair presentation of our financial position and results of operations. However, investors are cautioned that the sensitivity of financial statements to these methods, assumptions and estimates could create materially different results under different conditions or using different assumptions.

Below are those policies applied in preparing our financial statements that management believes are the most dependent on the application of estimates and assumptions. For additional accounting policies, see Note 3, “Summary of Significant Accounting Policies,” in the notes to the consolidated financial statements included herein.

Goodwill and Other Intangible Assets: In accordance with ASC 805, “Business Combinations,” the Company uses the acquisition method of accounting to allocate costs of acquired businesses to the assets acquired and liabilities assumed based on their estimated fair values at the dates of acquisition. The excess costs of acquired businesses over the fair values of the assets acquired and liabilities assumed were recognized as goodwill. The valuations of the acquired assets and liabilities will impact the determination of future operating results. In addition to using management estimates and negotiated amounts, the Company used a variety of information sources to determine the estimated fair values of acquired assets and liabilities including third-party appraisals for the estimated value and lives of identifiable intangible assets. Fair value adjustments to the Company’s assets and liabilities are recognized and the results of operations of the acquired business are included in our consolidated financial statements from the effective date of the merger or acquisition.

Intangible assets other than goodwill are recognized if the benefit of the intangible asset is obtained through contractual or other legal rights, or if the intangible asset can be sold, transferred, licensed or exchanged, regardless of the Company’s intent to do so. Goodwill and identifiable intangible assets are recorded at their estimated fair value on the date of acquisition and are reviewed at least annually for impairment based on cash flow projections and fair value estimates.

GAAP requires that the annual, and any interim, impairment assessment be performed at the reporting unit level. The reporting unit level is one level below an operating segment. Substantially all goodwill was determined and recognized for each reporting

Management, considering industry and company-specific historical and projected data, develops growth rates, sales projections and cash flow projections for each reporting unit. Terminal value rate determination follows common methodology of capturing the present value of perpetual cash flow estimates beyond the last projected period assuming a constant WACC and low long-term growth rates. As an indicator that each reporting unit has been valued appropriately through the use of the discounted cash flow valuation model, the aggregate of all reporting unit’s estimated fair value is reconciled to the total market capitalization of the Company.

The Company had 3435 reporting units with goodwill as of the first day of the fourth quarter of fiscal 2017,2018, the date of the last annual impairment test. The estimated fair values of each of the reporting units was substantially in excess of their respective carrying values, and therefore, no goodwill impairment was recorded. The Company performed a sensitivity analysis on the discount rate, which is a significant assumption in the calculation of fair values. With a one percentage point increase in the discount rate, nearly all of the reporting units would continue to have fair values substantially in excess of their respective carrying values.

Management tests indefinite-lived intangible assets for impairment at the asset level, as determined by appropriate asset valuation at the time of acquisition. The impairment test for indefinite-lived intangible assets consists of a comparison between the estimated fair values and carrying values. If the carrying amounts of intangible assets that have indefinite useful lives exceed their estimated fair values, an impairment loss will be recognized in an amount equal to the difference. Management utilizes the royalty savings valuation method to determine the estimated fair value for each indefinite-lived intangible asset. In this method, management estimates the royalty savings arising from the ownership of the intangible asset. The key assumptions used in estimating the royalty savings for impairment testing include discount rates, royalty rates, growth rates, sales projections and terminal value rates. Discount rates used are similar to the rates developed by the WACC methodology considering any differences in company-specific risk factors between reporting units and the indefinite-lived intangible assets. Royalty rates are established by management with the advice of valuation experts and periodically substantiated by valuation experts. Management, considering industry and company-specific historical and projected data, develops growth rates and sales projections for each significant intangible asset. Terminal value rate determination follows common methodology of capturing the present value of perpetual sales estimates beyond the last projected period assuming a constant WACC and low long-term growth rates.

The discounted cash flow and royalty savings valuation methodologies require management to make certain assumptions based upon information available at the time the valuations are performed. Actual results could differ from these assumptions. Management believes the assumptions used are reflective of what a market participant would have used in calculating fair value considering the current economic conditions.

The following table sets forth, for the periods indicated, certain operating data of the Company, including presentation of the amounts as a percentage of net sales (amounts in thousands):

The increase in fiscal year 2015.

The net increase in the dollar amount of cost of sales during the fiscal year ended September 30, 20162018 was primarily due to increased volume associated with the sales from acquisitions and organic sales growth.growth offset by a reduction in purchase accounting adjustments on inventory and a benefit from foreign exchange rate fluctuations.

Gross profit as a percentage of sales increased by 0.90.5 percentage points to 54.5%57.1% for the fiscal year ended September 30, 20162018 from 53.6%56.6% for the fiscal year ended September 30, 2015.2017. The dollar amount of gross profit increased by $278.3$192.9 million, or 19.2%9.7%, for the fiscal year ended September 30, 20162018 compared to the comparable period last year due to the following items: