As filed with the Securities and Exchange Commission on October 2, 2006

Registration No. 333-136978

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Amendment No. 3

to

Form S-4

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

ALLIS-CHALMERS ENERGY INC.

(Exact name of registrant as specified in its charter)

Co-Registrants

(See next page)

Copy to:

Andrews Kurth LLP

600 Travis, Suite 4200

Houston, Texas 77002

(713) 220-4200

Attn:     Henry Havre

                           Christopher S. Wade

     Approximate date of commencement of proposed sale to the public: As soon as practicable following the effectiveness of this registration statement.

     If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box. o

     If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

     If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

CALCULATION OF REGISTRATION FEE

     The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

Co-Registrants

EXPLANATORY NOTE

      The purpose of this Amendment No. 3 to Allis-Chalmers Energy Inc.’s Registration Statement on Form S-4 (Form No. 333-136978) is to file Exhibit 5.1.

PART II

INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 20.  Indemnification of Directors and Officers.

      The registrant’s Amended and Restated Certificate of Incorporation (the “Certificate of Incorporation”) and its by-laws provide for the indemnification by the registrant of each director, officer and employee of the registrant to the fullest extent permitted by the Delaware General Corporation Law, as the same exists or may hereafter be amended. Section 145 of the Delaware General Corporation Law provides in relevant part that a corporation may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that such person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with such action, suit or proceeding if such person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, had no reasonable cause to believe such person’s conduct was unlawful.

      In addition, Section 145 provides that a corporation may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by or in the right of the corporation to procure a judgment in its favor by reason of the fact that such person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise against expenses (including attorneys’ fees) actually and reasonably incurred by such person in connection with the defense or settlement of such action or suit if such person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of the corporation and except that no indemnification shall be made in respect of any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Delaware Court of Chancery or the court in which such action or suit was brought shall determine upon application that, despite the adjudication of liability but in view of all the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Delaware Court of Chancery or such other court shall deem proper. Delaware law further provides that nothing in the above described provisions shall be deemed exclusive of any other rights to indemnification or advancement of expenses to which any person may be entitled under any bylaw, agreement, vote of stockholders or disinterested directors or otherwise.

      The registrant’s Certificate of Incorporation provides that a director of the registrant shall not be liable to the registrant or its stockholders for monetary damages for breach of fiduciary duty as a director. Section 102(o)(7) of the Delaware General Corporation Law provides that a provision so limiting the personal liability of a director shall not eliminate or limit the liability of a director for, among other things: breach of the duty of loyalty; acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of the law; unlawful payment of dividends; and transactions from which the director derived an improper personal benefit.

      The registrant has entered into separate but identical indemnity agreements (the “Indemnity Agreements”) with each director of the registrant and certain officers of the registrant (the

“Indemnitees”). Pursuant to the terms and conditions of the Indemnity Agreements, the registrant indemnified each Indemnitee against any amounts which he or she becomes legally obligated to pay in connection with any claim against him or her based upon any action or inaction which he or she may commit, omit or suffer while acting in his or her capacity as a director and/or officer of the registrant or its subsidiaries, provided, however, that Indemnitee acted in good faith and in a manner Indemnitee reasonably believed to be in or not opposed to the best interests of the registrant and, with respect to any criminal action, had no reasonable cause to believe Indemnitee’s conduct was unlawful.

      (a) Exhibits. The exhibits listed in the accompanying Exhibit Index are filed (except where otherwise indicated) as part of this registration statement.

      (b) Financial Statement Schedules. No financial statement schedules are included in Part II of this registration statement because the information required to be set forth herein is not applicable or is shown in our consolidated financial statements or the notes thereto.

      (a) Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that, in the opinion of the Securities and Exchange Commission, such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless, in the opinion of its counsel, the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

      (b) The undersigned registrant hereby undertakes to respond to requests for information that is incorporated by reference into the prospectus pursuant to Items 4, 10(b), 11, or 13 of Form S-4, within one business day of receipt of such request, and to send the incorporated documents by first class mail or other equally prompt means. This includes information contained in documents filed subsequent to the effective date of the registration statement through the date of responding to the request.

      (c) The undersigned registrant hereby undertakes to supply by means of a post-effective amendment all information concerning a transaction, and the company being acquired involved therein, that was not the subject of and included in the registration statement when it became effective.

SIGNATURES

       Pursuant to the requirements of the Securities Act of 1933, the registrant has duly caused this amendment to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Houston, State of Texas, on this 2nd day of October, 2006.

     Pursuant to requirements of the Securities Act, this amendment has been signed on October 2, 2006 by the following persons in the capacities indicated.

      Pursuant to the requirements of the Securities Act of 1933, each of the co-registrants set forth below (the “Guarantors”) has duly caused this amendment to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Houston, State of Texas, on this 2nd day of October, 2006.

      Pursuant to the requirements of the Securities Act, this amendment has been signed on October 2, 2006 by the following persons in the capacities indicated.

EXHIBIT INDEX