Curtiss-Wright delivered exceptional performance in 2023. This was evidenced by numerous financial records, including full-year sales, profitability, diluted earnings per share, free cash flow, new orders and backlog. We achieved these results while accelerating investments in research and development (R&D), our systems and processes, and our people. With our strong free cash flow generation and disciplined approach to capital allocation, we concluded the year with a strong and stable balance sheet. This ensures we are well positioned to pursue strategic investments in our core businesses and acquisitions which will strengthen the product offering across our Aerospace & Defense (A&D) and Commercial portfolio. I'm incredibly pleased with our success to date in executing our Pivot to Growth strategy and look forward to building on this momentum to deliver long-term profitable growth and continued value creation for all stakeholders.
I'm incredibly pleased with
our success to date in
executing our Pivot to
Growth strategy and look
forward to building on
this momentum to deliver
long-term profitable
growth and value creation
for all stakeholders.
Sales increased 11% overall to a record $2.8 billion, driven by 10% organic growth reflecting higher sales in both our A&D and Commercial markets, and the contribution of the arresting systems business acquired in 2022. Adjusted operating income increased 11% to $494 million, while adjusted operating margin increased 10 basis points to 17.4%. This performance reflected improved profitability in all three segments as we continued to ramp up our investments in R&D across the portfolio.
Adjusted diluted earnings per share increased 15% to $9.38, while Adjusted free cash flow was $413 million, driving adjusted free cash flow conversion of 114%, which is a reflection on our strong growth in earnings and working capital management.
Growth in our order book was exceptionally strong, up 5% year-over-year to a record $3.1 billion, reflecting 1.1 times book to bill overall and solid demand across the majority of our markets. As a result, we concluded the year with a record backlog of $2.9 billion, up 9% year-over-year, driving confidence in our future growth outlook.
Due in large part to our strong results in 2023, we delivered a successful performance against the three-year financial targets established at our 2021 Investor Day, and generated strong growth in sales, operating income and diluted EPS. Overall, we generated 110 basis points in operating margin expansion and more than $1 billion in adjusted free cash flow over the period, despite the impacts of the pandemic and a very challenging supply chain environment. This performance against our commitments resulted in strong improvements in our stock price, along with increased investor confidence in our Company and execution track record.
We are strategically
investing to advance our
technologies and leverage
Curtiss-Wright's strong
alignment to favorable
secular growth trends.
We are strategically investing to advance our technologies and leverage Curtiss-Wright's strong alignment to favorable secular growth trends. Given the long-term nature of many of our businesses, we are constantly evaluating these critical investments over various time horizons and their potential to drive long-term profitable growth. In 2023, we made strong incremental investments in R&D across the business to further position us for future organic growth and we anticipate a similar increase in our total engineering spending, again, in 2024. As we continue to invest in our Company, we will advance both operational and commercial excellence across the organization, to open new funding pathways for future investments. Overall, we remain dedicated to investing across the portfolio while continuing to expand Curtiss-Wright's operating margin.
We continue to remain focused on reducing working capital. This focus, along with consistent top line growth, will result in strong free cash flow generation to support an efficient capital allocation strategy. We remain disciplined in our approach towards potential acquisitions, and while we did not acquire any businesses this past year, we maintained steady distributions to our shareholders through our ongoing share repurchase program and continued to increase in our quarterly dividend. We concluded 2023 with a strong and healthy balance sheet, with approximately $2.3 billion of borrowing capacity, providing the financial flexibility that will enable us to strategically enhance our portfolio in 2024 and beyond with high-quality acquisitions in support of our Pivot to Growth strategy.
As we enter our 95th year as a public company, I would like to thank our approximately 8,600 employees for their dedication to driving Curtiss-Wright to yet another record performance this past year. We have steadily grown our workforce as we have improved our top-line sales, with a keen focus on employee retention, training, talent acquisition and development to secure and enhance our employee base for decades to come. We continue to roll out new systems, tools and processes to better enable our team to drive efficiency and performance in our operations, laying a strong foundation to support Curtiss-Wright's future growth.
Finally, at our upcoming May 2024 investor day, we look forward to updating you on the success of our Pivot to Growth strategy and organic growth initiatives, and sharing our new long-term financial targets, as we position Curtiss-Wright to deliver long-term profitable growth and tremendous value for our shareholders, our employees and our customers.
Lynn M. Bamford
Chair & Chief Executive Officer