UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 7)*

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

with a copy to:

Squire, Sanders & Dempsey (US) LLP

8000 Towers Crescent Drive, 14th Floor

Tysons Corner, VA 22182

Attention: James J. Maiwurm

Telephone: (703) 720-7890

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

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CUSIP No. 00211E104

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CUSIP No. 00211E104

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CUSIP No. 00211E104

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CUSIP No. 00211E104

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Explanatory Note

This Amendment No. 7 (this “Amendment”) amends and supplements the Schedule 13D originally filed with the Securities and Exchange Commission (the “SEC”) on January 19, 2007 and amended on January 31, 2007, June 29, 2007 (by two filings), October 17, 2007, May 23, 2008 and March 19, 2009. This Amendment is being filed to report a change in beneficial ownership by Daniel Colon, as well as update the current holdings of Messrs. Joel R. Jacks and Peter M. Schulte.

Mr. Colon has sold an aggregate 27,559 shares of common stock, par value $0.0001 per share (the “Common Stock”) of ATS Corporation since January 4, 2011, culminating with a recent sale on June 10, 2011. Specifically, he sold 2,959 shares on January 4, 2011; 5,400 shares on February 3, 2011; 700 shares on April 7, 2011; 100 shares on April 14, 2011; 900 shares on April 20, 2011; 570 shares on April 21, 2011; 8,660 shares on April 25, 2011; 270 shares on April 26, 2011; 1,100 shares on June 3, 2011; and 6,900 shares on June 10, 2011. As of the date of this report, Mr. Colon beneficially owns less than 1% of the Common Stock of ATS Corporation.

On May 18, 2010, Mr. Jacks acquired 17,930 shares of Common Stock, as reported on a Form 4 filed with the SEC on May 20, 2010. Of the 17,930 shares, 8,275 were restricted shares issued to Mr. Jacks as a director of the Company and 9,655 shares were issued to him for his annual director retainer, in lieu of cash. On May 5, 2009, Mr. Jacks acquired 34,666 shares of Common Stock, as reported on a Form 4 filed May 7, 2009. Of those 34,666 shares, 16,000 were restricted shares issued to directors by the Company and 18,666 were issued in lieu of cash for the annual director retainer. The total amount of beneficially owned common stock held by Joel R. Jacks is 1,394,528 shares representing 6.1% of the total amount of Common Stock outstanding.

Mr. Schulte acquired 19,654 shares of Common Stock on May 18, 2010, as reported on a Form 4 filed with the SEC on May 20, 2010. Of the 19,654 shares, 8,275 were restricted shares issued to Mr. Schulte as a director of the Company, and 11,379 shares were issued to him for his annual director retainer, in lieu of cash. Mr. Schulte purchased 3,000 shares of Common Stock on May 19, 2009 at $1.58 per share, as reported on a Form 4 filed May 21, 2009. On May 5, 2009, Mr. Schulte acquired 34,000 shares of Common Stock, as reported on a Form 4 filed May 7, 2009. Of those 34,000 shares, 16,000 were restricted shares issued to directors by the Company and 18,000 were issued in lieu of cash for the annual director retainer. The total amount of beneficially owned common stock held by Mr. Schulte is 1,298,154 shares, or 5.7% of the total amount of Common Stock outstanding. Unless otherwise stated, the information set forth in the original Schedule 13D and its amendments remains accurate in all respects.

Joel R. Jacks, Peter Schulte, Wesley Gaus and Daniel Colon, Jr. file as a “group,” as such term is used in Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, due to their affiliation with CM Equity, as further described below.

The class of equity securities to which this Schedule 13D/A relates is the Common Stock of ATS Corporation, a Delaware corporation formerly known as Federal Services Acquisition Corporation (the “Issuer”). The address of the principal executive offices of the Issuer is 7925 Jones Branch Drive, McLean, VA 22102.

This Amendment is filed on behalf of each the following persons pursuant to Rule 13d-1(k) promulgated by the Securities and Exchange Commission (the “Commission”) pursuant to Section 13 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”):

Joel R. Jacks (“Jacks”),

Peter M. Schulte (“Schulte”),

Wesley Gaus (“Gaus”), and

Daniel Colon, Jr. (“Colon”).

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Jacks, Schulte, Gaus and Colon are collectively referred to herein as the “Reporting Persons.” The Reporting Persons may be deemed to constitute a “group” for purposes of Section 13(d)(3) of the Exchange Act. The Reporting Persons expressly disclaim that they have agreed to act as a group other than as described in this statement.

This Amendment relates to (i) 1,394,528 shares of Common Stock held by Jacks, (ii) 1,298,154 shares of Common Stock held by Schulte, (iii) 229,994 shares of Common Stock held by Gaus, and (iv) 12,765 shares of Common Stock held by Colon (collectively, the “Shares”). Each of these individuals is associated with and employed by CM Equity Partners, L.P. (“CM Equity”), a company that invests in established middle market companies and manages private equity funds and investments through its management company, CM Equity Management, L.P. Jacks and Schulte are the Managing Partners and founders of CM Equity.

Each of Jacks and Schulte is serving as a director of the Issuer.

The business address of Jacks, Schulte, Gaus and Colon is 900 Third Avenue, 33^rd Floor, New York, New York 10022.

During the past five years, none of the Reporting Persons nor, to the best knowledge of the Reporting Persons, any other person identified in response to this Item 2, has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or was a party to a civil proceeding of a judicial or administrative body of competent jurisdiction as a result of which such person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws, or finding any violation with respect to such laws.

Each of the individual Reporting Persons is a citizen of the United States.

Mr. Schulte purchased 3,000 shares of Common Stock on May 19, 2009. All other shares acquired by Messrs. Jacks and Schulte were issued by the Company by virtue of their director status.

The Reporting Persons acquired the Shares for investment purposes. The Reporting Persons may, from time to time, depending upon market conditions and other factors deemed relevant by the Reporting Persons, acquire additional shares of Common Stock. The Reporting Persons reserve the right to, and may in the future choose to, change their purpose with respect to their investment and take such actions as they deem appropriate in light of the circumstances including, without limitation, to dispose of, in the open market, in a private transaction or by gift, all or a portion of the shares of Common Stock which they now own or may hereafter acquire.

At the date of this statement, the Reporting Persons, except as set forth in this statement and consistent with Jacks’ and Schulte’s positions with the Issuer, have no plans or proposals which would result in:

(a) The acquisition by any person of additional securities of the Issuer, or the disposition of securities of the Issuer;

(b) An extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of its subsidiaries;

(c) A sale or transfer of a material amount of assets of the Issuer or any of its subsidiaries;

(d) Any change in the present board of directors or management of the Issuer, including any plans or proposals to change the number or term of directors or to fill any existing vacancies on the board;

(e) Any material change in the present capitalization or dividend policy of the Issuer;

(f) Any other material change in the Issuer’s business or corporate structure;

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(g) Changes in the Issuer’s charter, bylaws or instruments corresponding thereto or other actions which may impede the acquisition of control of the Issuer by any person;

(h) Causing a class of securities of the Issuer to be delisted from a national securities exchange or to cease to be authorized to be quoted in an inter-dealer quotation system of a registered national securities association;

(i) A class of equity securities of the issuer becoming eligible for termination of registration pursuant to Section 12(g)(4) of the Exchange Act; or

(j) Any action similar to any of those actions enumerated above.

All of the percentages calculated in this Amendment are based on 22,922,508 shares of Common Stock outstanding as of the close of business on May 12, 2011, as reported in the Issuer’s Quarterly Report on Form 10-Q as filed with the Securities and Exchange Commission on May 16, 2011.

In the aggregate and without duplication, as of the date of this statement, the Reporting Persons may be deemed to be the beneficial owners of an aggregate of 2,935,441 shares of Common Stock, which represents approximately 12.8% of the Common Stock outstanding as of the date of this statement. As set forth below, each of the Reporting Persons expressly disclaims beneficial ownership of shares of Common Stock as to which he does not have actual voting and dispositive power.

As of the date of this Amendment, Jacks may be deemed to be the beneficial owner of an aggregate of 1,394,528 shares of Common Stock, which represents approximately 6.1% of the Common Stock outstanding as of the date of this statement. Jacks has the sole power to vote or direct the vote of, and to dispose or direct the disposition of, all such shares.

As of the date of this Amendment, Schulte may be deemed to be the beneficial owner of an aggregate of 1,298,154 shares of Common Stock, which represents approximately 5.7% of the Common Stock outstanding as of the date of this statement. Schulte has the sole power to vote or direct the vote of, and to dispose or direct the disposition of, all such shares.

As of the date of this Amendment, Gaus may be deemed to be the beneficial owner of an aggregate of 229,994 shares of Common Stock, which represents approximately 1.0% of the Common Stock outstanding as of the date of this statement. Gaus has the sole power to vote or direct the vote of, and to dispose or direct the disposition of, all such shares.

As of the date of this Amendment, Colon may be deemed to be the beneficial owner of 12,765 shares of Common Stock, which represents less than 1% of the Common Stock outstanding as of the date of this Amendment. Colon has the sole power to vote or direct the vote of, and to dispose or direct the disposition of, all such shares.

No material change.

Exhibit 99.1. Joint Filing Agreement (included as Exhibit 99.1 to the Schedule 13D/A filed on October 17, 2007)

Exhibit 99.2. Form of Escrow Agreement entered into by the Issuer and certain of its stockholders and Continental Stock Transfer & Trust Company (included as Exhibit 10.17 to the Issuer’s Registration Statement on Form S-1, as amended (Registration No. 333-124638), and incorporated herein by reference)

Exhibit 99.3. Form of Registration Rights Agreement entered into by the Issuer and certain of its stockholders (included as Exhibit 10.14 to the Issuer’s Registration Statement on Form S-1, as amended (Registration No. 333-124638), and incorporated herein by reference)

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Exhibit 99.4. Amendment to Registration Rights Agreement entered into by the Issuer and certain of its stockholders (included as Exhibit 99.4 to the Schedule 13D/A filed June 29, 2007 and incorporated herein by reference)

Exhibit 99.5. Amended and Restated Stock Escrow Agreement entered into by the Issuer, the former members of FSAC Partners, LLC, certain stockholders of the Issuer and Continental Stock Transfer & Trust Company (included as Exhibit 99.5 to the Schedule 13D/A filed June 29, 2007 and incorporated herein by reference)

Exhibit 99.6. Joel R. Jacks Power of Attorney (included as Exhibit 99.4 to the Schedule 13D filed January 19, 2007 and incorporated herein by reference)

Exhibit 99.7. Peter M. Schulte Power of Attorney (included as Exhibit 99.5 to the Schedule 13D filed January 19, 2007 and incorporated herein by reference)

Exhibit 99.8. Wesley Gaus Power of Attorney (included as Exhibit 99.8 to the Schedule 13D filed January 19, 2007 and incorporated herein by reference)

Exhibit 99.9. Daniel Colon, Jr. Power of Attorney (included as Exhibit 99.10 to the Schedule 13D filed January 19, 2007 and incorporated herein by reference)

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: July 1, 2011

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EXHIBIT INDEX

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