Exhibit 5.1

	330 North Wabash Avenue
	Suite 2800
	Chicago, Illinois 60611
	Tel: +1.312.876.7700 Fax: +1.312.993.9767
	www.lw.com
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October 2, 2025	Dubai	Riyadh
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AAR CORP.

1100 N. Wood Dale Road

Wood Dale, Illinois 60191

Re: Registration Statement on Form S-3 (Registration No. 333-273312); 3,450,000 shares of Common Stock, par value $1.00 per share

To the addressees set forth above:

We have acted as special counsel to AAR CORP., a Delaware corporation (the “Company”), in connection with the proposed issuance of 3,450,000 shares (including up to 450,000 shares issuable upon exercise of the underwriters’ option to purchase additional shares) of common stock of the Company, $1.00 par value per share (the “Shares”). The Shares are included in a registration statement on Form S-3 under the Securities Act of 1933, as amended (the “Act”), filed with the Securities and Exchange Commission (the “Commission”) on July 19, 2023 (Registration No. 333–273312) (as so filed and as amended, the “Registration Statement”), a base prospectus, dated July 18, 2023, included in the Registration Statement at the time it originally became effective (the “Base Prospectus”), a preliminary prospectus supplement, dated September 30, 2025, filed with the Commission pursuant to Rule 424(b) under the Act (together with the Base Prospectus, the “Preliminary Prospectus Supplement”), a prospectus supplement dated September 30, 2025 filed with the Commission pursuant to Rule 424(b) under the Act (together with the Base Prospectus, the “Prospectus”). The Shares are being sold pursuant to an underwriting agreement dated September 30, 2025 by and between Goldman Sachs & Co. LLC, as representative of the several underwriters listed on Schedule I thereto, and the Company (the “Underwriting Agreement”). The term “Shares” shall include any additional shares of common stock registered by the Company pursuant to Rule 462(b) under the Act in connection with the offering contemplated by the Registration Statement.

This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement, the Preliminary Prospectus Supplement or the Prospectus, other than as expressly stated herein with respect to the issue of the Shares.

October 2, 2025
Page 2

 

As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters. We are opining herein as to the General Corporation Law of the State of Delaware (the “DGCL”), and we express no opinion with respect to any other laws.

Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Shares shall have been duly registered on the books of the transfer agent and registrar therefor in the name or on behalf of the purchasers and have been issued by the Company against payment therefor in the circumstances and pursuant to the terms contemplated by the Underwriting Agreement, the issue and sale of the Shares will have been duly authorized by all necessary corporate action of the Company, and the Shares will be validly issued, fully paid, and nonassessable. In rendering the foregoing opinion, we have assumed that the Company will comply with all applicable notice requirements regarding uncertificated shares provided in the DGCL.

This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. We consent to your filing this opinion as an exhibit to the Company’s Current Report on Form 8-K, dated October 2, 2025, and to the reference to our firm in the Prospectus under the heading “Legal Matters.” In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.

Sincerely,

/s/ Latham & Watkins LLP