* Sees 2018 free cash flow $550 mln-$600 mln
* Q4 adj. EPS $1.32 vs est $1.21
* Shares fall as much as 10 pct (Adds details from the conference call, background)
Feb 2 (Reuters) - Shares of Spirit AeroSystems Holdings Inc slumped as much as 10 percent on Friday after the aircraft parts maker said higher capital expenditure would take a toll on its 2018 free cash flow target.
The company, which makes sections of the fuselage, wing frame work and structural components, plans to ramp up production as robust demand for air travel encourages two of its biggest customers, Boeing Co and Airbus, to lift delivery targets.
Savings from changes to the U.S. tax code will be used for "high-return" capital expenditures and research and development activities, Chief Executive Tom Gentile said in a statement.
The comments come as several U.S. companies have said they would return at least a portion of their tax gains to shareholders through buyback and dividends.
Wichita, Kansas-based Spirit Aero's shares were on track to post their worst intraday percentage loss in nearly two years.
Free cash flow, a measure of how much cash a business generates after accounting for capital expenditures, is expected to be between $550 million and $600 million in 2018, the company said.
"The consensus (for free cash flow forecast) for 2018 was $612 million," Seaport Global Securities analyst Josh Sullivan said.
Spirit Aero plans to hire more workers and invest in 3D printing and automation as it looks to counter "significant operational challenges" to meet demand from aircraft makers.
However, the jump in deliveries helped the company beat revenue and profit estimates for the fourth quarter.
Spirit Aero earned $1.32 per share on an adjusted basis in the quarter ended Dec. 31, beating the average estimate of $1.21.
Total revenue rose 9.2 percent to $1.71 billion, above the $1.66 billion expected by analysts.
The company in August reached an agreement with Boeing on pricing terms, ending months of uncertainty over its ties to its largest customer, while giving clarity on its long-term cash flow.
Spirit Aero's stock had risen about 69 percent since the Boeing deal was announced. (Reporting by Ankit Ajmera in Bengaluru; Editing by Maju Samuel and Anil D'Silva)