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As filed with the Securities and Exchange Commission on December 5, 2012

Registration No. 333-185250

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Amendment No. 1
to
Form S-4
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

AAR CORP.
(Exact name of Registrant as specified in its charter)

One AAR Place
1100 N. Wood Dale Road
Wood Dale, Illinois 60191
(630) 227-2000
(Address, including zip code, and telephone number, including area code, of Registrant's principal executive offices)

See Table of Additional Registrants Below

Approximate date of commencement of proposed sale of the securities to the public:
As soon as practicable after the effective date 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, 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

          Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of "large accelerated filer," "accelerated filer" and "smaller reporting company" in Rule 12b-2 of the Exchange Act. (Check one):

          If applicable, place an ý in the box to designate the appropriate rule provision relied upon in conducting this transaction:

          Exchange Act Rule 13e-4(i) (Cross-Border Issue Tender Offer) o

          Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer) o

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CALCULATION OF REGISTRATION FEE

(1)

Estimated pursuant to Rule 457(f) under the Securities Act of 1933, as amended, solely for the purposes of calculating the registration fee.

(2)

Pursuant to Rule 457(n) under the Securities Act of 1933, as amended, no separate consideration will be received for the guarantee.

          The Registrants hereby amend this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrants 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, as amended, 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.

   

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Table of Additional Registrants(1)(2)(3)

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EXPLANATORY NOTE

        This Amendment No. 1 is being filed for the purpose of filing Exhibits 5.4 and 5.5 to the Registration Statement (Registration No. 333-185250). No other changes or additions are being made to the Prospectus constituting Part I of the Registration Statement (not included herein) or to Part II of the Registration Statement.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 20.    Indemnification of Directors and Officers

        Article Fourteenth of AAR CORP.'s Restated Certificate of Incorporation provides that no director of AAR CORP. shall have personal liability to AAR CORP. or its stockholders for monetary damages for breach of fiduciary duty as a director, but this provision does not eliminate or limit the liability of a director (a) for any breach of the director's duty of loyalty to AAR CORP. or its stockholders, (b) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (c) under section 174 of the General Corporation Law of the State of Delaware (the "DGCL") or (d) for any transaction from which the director derived an improper personal benefit.

        Reference is made to Section 145 of the DGCL, which provides for indemnification of directors and officers in certain circumstances. Section 145 empowers a Delaware corporation to indemnify any persons who are, or are threatened to be made, parties to any threatened, pending or completed legal action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of such corporation), by reason of the fact that such person is or was an officer, director, employee or agent of such corporation, or is or was serving at the request of such corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise. The indemnity may include 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, provided that such officer, director, employee or agent acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the corporation's best interests, and, for criminal proceedings, had no reasonable cause to believe his or her conduct was unlawful. A Delaware corporation may indemnify officers and directors in an action by or in the right of the corporation under the same conditions, except that no indemnification is permitted without judicial approval if the officer or director is adjudged to be liable to the corporation. Where an officer or director is successful on the merits or otherwise in the defense of any action referred to above, the corporation must indemnify him or her against the expenses which such officer or director actually and reasonably incurred.

        Article Fifteenth of AAR CORP.'s Restated Certificate of Incorporation provides for indemnification of AAR CORP.'s officers and directors (and those serving in such capacity with another corporation at the request of AAR CORP.) to the fullest extent provided by the DGCL and other applicable laws as currently in effect and as they may be amended in the future.

        AAR CORP. has directors' and officers' liability insurance which provides, subject to certain policy limits, deductible amounts and exclusions, coverage for all persons who have been, are or may in the future be, directors or officers of AAR CORP. against amounts which such persons must pay resulting from claims made against them by reason of their being such directors or officers during the policy period for certain breaches of duty, omissions or other acts done or wrongfully attempted or alleged.

        AAR CORP. has entered into Indemnification Agreements with each of its directors and executive officers containing, among other things, provisions similar to those in AAR CORP.'s Restated Certificate of Incorporation, including provisions requiring indemnification to the full extent permitted by the DGCL and the prompt advancement of expenses under certain circumstances. In addition, the

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Indemnification Agreements require AAR CORP. to maintain directors' and officers' liability insurance at specified levels, subject to certain exceptions, and, if such coverage is not maintained, to indemnify the directors and executive officers to the full extent of such coverage.

        The charters and other organizational documents of each of the Guarantor Registrants allow for indemnification of the directors and officers thereof to the fullest extent permissible under applicable law. Furthermore, as directors and officers of subsidiaries of AAR CORP., the directors and officers of each of the Guarantor Registrant's is entitled to indemnification by AAR CORP. to the same extent as directors and officers of AAR CORP. and are covered by AAR CORP.'s directors' and officers' liability insurance to the same extent as directors and officers of AAR CORP.

Item 21.    Exhibits and Financial Statement Schedules

        The Exhibits filed herewith are set forth on the Exhibit Index filed as part of this registration statement.

Item 22.    Undertakings

        (a)   Each of the undersigned Registrants hereby undertakes:

        (1)   To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

          (i)  To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

         (ii)  To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Securities and Exchange Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20 percent change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement; and

        (iii)  To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement.

        (2)   That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

        (3)   To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

        (4)   That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser, each prospectus filed pursuant to Rule 424(b) as part of a registration statement relating to an offering, other than registration statements relying on Rule 430B or other than prospectuses filed in reliance on Rule 430A, shall be deemed to be part of and included in the registration statement as of the date it is first used after effectiveness. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such first use, supersede or modify any statement that was made in the

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registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such date of first use.

        (5)   That, for the purpose of determining liability of the Registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities, each of the undersigned Registrants undertakes that in a primary offering of securities of the undersigned Registrants pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned Registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

          (i)  Any preliminary prospectus or prospectus of such undersigned Registrant relating to the offering required to be filed pursuant to Rule 424;

         (ii)  Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned Registrant or used or referred to by the undersigned Registrant;

        (iii)  The portion of any other free writing prospectus relating to the offering containing material information about the undersigned Registrant or its securities provided by or on behalf of the undersigned Registrant; and

        (iv)  Any other communication that is an offer in the offering made by the undersigned Registrant to the purchaser.

        (b)   Each of the undersigned Registrants hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

        (c)   Each of the undersigned Registrants hereby undertakes:

        (1)   That prior to any public reoffering of the securities registered hereunder through use of a prospectus which is part of this registration statement, by any person or party who is deemed to be an underwriter within the meaning of Rule 145(c), the issuer undertakes that such reoffering prospectus will contain the information called for by the applicable registration form with respect to reofferings by persons who may be deemed underwriters, in addition to the information called for by the other Items of the applicable form.

        (2)   That every prospectus: (i) that is filed pursuant to the immediately preceding paragraph, or (ii) that purports to meet the requirements of Section 10(a)(3) of the Act and is used in connection with an offering of securities subject to Rule 415, will be filed as a part of an amendment to the registration statement and will not be used until such amendment is effective, and that, for purposes of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offering therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

        (d)   Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of any Registrant pursuant to the foregoing provisions, or otherwise, the undersigned Registrants have been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the 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

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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 Act and will be governed by the final adjudication of such issue.

        (e)   Each of the undersigned Registrants hereby undertakes:

        (1)   To respond to requests for information that is incorporated by reference into the prospectus pursuant to Item 4, 10(b), 11 or 13 of this Form, 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 the documents filed subsequent to the effective date of the registration statement through the date of responding to the request.

        (2)   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.

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, AAR CORP. has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, each of the companies listed below has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, each of the companies listed below has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, each of the companies listed below has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, Summa Technology, Inc. has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, each of the companies listed below has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, AARIFS (290) LLC has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, AARIFS (24750) LLC has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, AAR/SSB II, LLC has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, AARIFS A320 LLC has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, AAR Landing Gear LLC has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, Nordisk Aviation Products AS has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, Telair International GmbH has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, Telair International AB has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wood Dale, State of Illinois, on this 5th day of December 2012.

        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed effective December 5, 2012 by the following persons in the capacities and on the dates indicated.

 

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EXHIBIT INDEX

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*

Previously filed

**

Filed herewith

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QuickLinks

Table of Additional Registrants(1)(2)(3)
EXPLANATORY NOTE
PART II INFORMATION NOT REQUIRED IN PROSPECTUS

Item 20. Indemnification of Directors and Officers
Item 21. Exhibits and Financial Statement Schedules
Item 22. Undertakings

SIGNATURES
SIGNATURES
SIGNATURES
EXHIBIT INDEX