AMENDMENT NO. 2 TO GUARANTY AGREEMENT

          THIS AMENDMENT NO. 2 to GUARANTY AGREEMENT (this "Amendment No.
     2") dated as of September [sic October]    , 1994, among United
                                             ---
     Industrial Corporation, a Delaware corporation (herein called the
     "Guarantor"), to Principal Mutual Life Insurance Company and The
     Travelers Insurance Company (collectively, the "Purchasers") and their
     respective successors and assigns as holders of the Notes hereinafter
     described (the "Noteholders").

                               W I T N E S S E T H
                               - - - - - - - - - -
          WHEREAS, the Guarantor and the Noteholders have heretofore
     entered into a Guaranty Agreement dated as of July 15, 1992 (the
     "Guaranty Agreement"); 

          WHEREAS, the Guarantor and the Noteholders have heretofore
     entered into an Amendment No. 1 to the Guaranty Agreement dated as of
     July 15, 1993 (the "Amendment No. 1");
         
          WHEREAS, the Guarantor has requested that the Noteholders agree
     to amend certain provisions and covenants contained in the Guaranty
     Agreement, as amended; and

          WHEREAS,  the Noteholders are willing to amend such provisions
     and covenants upon the terms and conditions herein provided.

          NOW, THEREFORE, the parties hereto, in consideration of the
     mutual promises made herein, the sufficiency of which is hereby
     acknowledged, hereby agree as follows:

          Section 1.      Definitions; References.     Unless otherwise
                          -----------------------
     specifically defined herein, each term used herein which is defined in
     the Guaranty Agreement, as amended shall have the meaning assigned to
     such term in the Guaranty Agreement, as amended.  Each reference to
     "hereof," "hereunder," "herein" and "hereby" and each other similar
     reference to in "this Agreement," and each other similar reference
     contained in the Guaranty Agreement, Amendment No. 1 or Amendment No.
     2, shall from and after the date hereof refer to the Guaranty
     Agreement as amended by Amendment No. 1 and this Amendment No. 2.

          Section 1.1.   The following definitions are hereby added to the
     definitions under the Guaranty Agreement, as amended:

          ""Agent":  as of the date of the Credit Agreement, First
          Fidelity Bank, National Association in its



























     

          capacity as party to the Credit Agreement as "Agent," and, after
          the date of the Credit Agreement, the person from time to time,
          party to the Credit Agreement as "Agent."

          "Aggregate Loans Outstanding":  as to any Lender at a
          particular time, the aggregate principal amount of the
          Revolving Credit Loans of such Lender outstanding at such
          time.

          "Borrower":  shall mean AAI Corporation, a Maryland
          Corporation.

          "Collateral Agent":  shall mean as of the date of this
          Amendment No. 2, First Fidelity Bank, National Association
          in its capacity as party to the Intercreditor Agreement as
          "Collateral Agent," and, after the date of this Amendment
          No. 2, the person from time to time, party to the
          Intercreditor Agreement as "Collateral Agent."

          "Collateral Agent Liens":  shall mean, as the same may be
          amended, waived, modified, extended, renewed, supplemented
          or replaced from time to time, all security interests,
          liens, assignments and other encumbrances in or upon any
          property (real, personal or mixed) granted in favor of
          Collateral Agent pursuant to the Security Documents.
       
          "Credit Agreement":  shall mean, as the same may be amended,
          waived, modified, extended, renewed, supplemented or
          replaced from time to time, that certain Credit Agreement of
          even date herewith among Agent, Borrower, Lenders and
          Issuing Bank.

          "First Fidelity":  shall mean First Fidelity Bank, National
          Association.

          "Governmental Authority":  shall mean any nation or
          government, any state or other political subdivision thereof
          and any entity exercising executive, legislative, judicial
          regulatory or administrative functions of or pertaining to
          government, and any Person owned or controlled directly or
          indirectly by any of the foregoing, whether domestic or
          foreign.

          "Intercreditor Agreement":  shall mean, as the same may be
          amended, waived, modified, extended, renewed,





























     NYFS11...:\95\78495\0001\7120\GUA02894.E40



     

          supplemented or replaced from time to time, that certain
          Intercreditor Agreement of even date herewith by and among The
          Travelers Insurance Company, a Connecticut corporation, Principal
          Mutual Life Insurance Company, an Iowa corporation, First
          Fidelity Bank, National Association in its capacity as Lender, in
          its capacity as Agent, in its capacity as Issuing Bank, and in
          its capacity (in such capacity, "Collateral Agent") as grantee
          and beneficiary of the Collateral Agent Liens, and The Bank of
          Baltimore in its capacity as Lender."

          "Issuing Bank":  shall mean, as of the date of the Credit
          Agreement, First Fidelity Bank, National Association, in its
          capacity as party to the Credit Agreement as "Issuing Bank,"
          and, after the date of the Credit Agreement, the person from
          time to time party to the Credit Agreement as "Issuing
          Bank."  

          "L/C Agreements":  shall mean, as amended, modified,
          extended, renewed, supplemented or replaced from time to
          time, applications and reimbursement and other agreements in
          form and content and executed by Persons satisfactory to the
          Issuing Bank requesting issuance of one or more Letters of
          Credit and setting forth reimbursement obligations and other
          terms and conditions relating thereto.

          "Lenders":  shall mean, as of the date of the Credit
          Agreement, First Fidelity Bank, National Association, and
          Bank of Baltimore, each in its capacity as party to the
          Credit Agreement as a "Lender," and, after the date of the
          Credit Agreement, all persons from time to time parties to
          the Credit Agreement as "Lenders."

          "Letter of Credit":  shall mean, commercial and standby
          letters of credit issued for the account of the Borrower,
          for such purposes, in such amounts, for the benefit of such
          Persons and subject to such terms and conditions as may be
          acceptable to the Issuing Bank and the Required Lenders in
          their discretion exercised in good faith (individually, as
          amended, modified, extended, renewed, supplemented or
          replaced from time to time, a "Letter of Credit," and
          collectively, the "Letters of Credit"). 

          "Person":  an individual, partnership, corporation, limited
          liability company, business trust, joint stock






























     



     

          company, trust, unincorporated association, joint venture,
          Governmental Authority or other entity of whatever nature.  

          "Required Lenders":  at a particular time, a Lender or
          Lenders holding more than sixty percent (60%) of the
          Aggregate Loans Outstanding of all Lenders under the Credit
          Agreement as at such time or, if no Lender has any Revolving
          Credit Loans outstanding under the Credit Agreement from
          time to time, a Lender or Lenders whose commitment
          percentages as identified in the Credit Agreement aggregate
          more than sixty percent (60%) as at such time. 

          "Restricted Subsidiaries":  shall mean (i) AAI Engineering
          Support, Inc., a Maryland corporation, AAI Microflite
          Simulation International Corporation, a Maryland
          Corporation, AAI/ACL Technologies, Inc., a Maryland
          corporation, Seti, Inc., a Pennsylvania corporation, AAI
          Systems Management, Inc., a Maryland corporation and AAI
          California Carshell, Inc., a Maryland corporation; (ii) any
          other Subsidiary with respect to which the Company has
          notified the Noteholders that it has been designated as such
          by the Board of Directors of
          the Company or by an Executive Officer of the Company who
          has been authorized by such Board of Directors to make such
          designation; and (iii) Symtron Systems, Inc., a New Jersey
          corporation, a wholly owned subsidiary of Guarantor.

          "Revolving Credit Loans":  at a particular time and from
          time to time the revolving credit loans made by Lender or
          Lenders to the Borrower under Section 2.1 of the Credit
          Agreement.

          "Revolving Credit Notes":  shall mean the promissory notes
          of the Borrower evidencing the revolving credit loan or
          loans made under the Credit Agreement, from time to time,
          appropriately completed, as amended, modified, extended,
          renewed, supplemented or replaced from time to time, payable
          to the order of such Lender and further evidencing the
          obligation of the Borrower to pay with interest the
          aggregate loans outstanding under the Credit Agreement to
          such Lender from time to time.

































     



     

          "Security Documents":  shall mean, as the same may be
          amended, waived, modified, extended, renewed, supplemented
          or replaced from time to time, that certain Pledge and
          Security Agreement of even date herewith executed and
          delivered by the Borrower in favor of Collateral Agent, that
          certain Security Agreement of even date herewith executed
          and delivered by the Borrower in favor of the Collateral
          Agent, that certain Security Agreement of even date herewith
          executed and delivered by the Restricted Subsidiaries and
          Guarantor, et al in favor of Collateral Agent, that certain
          Pledge and Security Agreement of even date herewith executed
          and delivered by the Guarantor in favor of the Collateral
          Agent, that certain Deed of Trust and Security Agreement of
          even date herewith executed and delivered by Borrower in
          favor of certain trustees for the benefit of the Collateral
          Agent, that certain Assignment of Leases and Rents of even
          date herewith executed and delivered by the Borrower in
          favor of the Collateral Agent, that certain Collateral
          Assignment of Trademarks of even date herewith executed and
          delivered by Borrower in favor of the Collateral Agent, that
          certain Collateral Assignment of Patents of even date
          herewith executed and delivered by Borrower in favor of the
          Collateral Agent, that certain Collateral Assignment of
          Trademarks of even date herewith executed and delivered by
          Symtron Systems, Inc. in favor of the Collateral Agent, that
          certain Collateral Assignment of 

          Patents of even date herewith executed and delivered by
          Symtron Systems, Inc. in favor of the Collateral Agent, that
          certain Collateral Assignment of Trademarks of even date
          herewith executed and delivered by AAI/ACL Technologies,
          Inc. in favor of the Collateral Agent, that certain
          Collateral Assignment of Patents of even date herewith
          executed and delivered by AAI/ACL Technologies, Inc. in
          favor of the Collateral Agent, and that certain Collateral
          Assignment of Copyrights of even date herewith executed and
          delivered by AAI/ACL Technologies, Inc. in favor of the
          Collateral Agent.

          "Subsidiary":  of a Person means (i) any corporation or
          other entity of which securities or other ownership
          interests having ordinary voting power to elect a majority
          of the board of directors or other persons performing
          similar functions are at the time, directly or indirectly,
          owned by such Person, or (ii) the





























     



     

          management of which is otherwise controlled, directly or
          indirectly, through one or more intermediaries, by such Person.

          "Symtron":  shall mean Symtron Systems, Inc., a New Jersey
          corporation."
        
          Section 2.     Section 5. (e) Restriction on Liens.
                         -----------------------------------
     Subsections (6), (7) and (8) be and hereby are added to Section 5. (e)
     of the Guaranty Agreement, as amended, as follows:
      
               "(6)  Liens in favor of the Collateral Agent
               created pursuant to the Security Documents
               securing the obligations under the Credit
               Agreement and the Revolving Credit Notes and under
               the Note Purchase Agreement and the Notes.

               (7)  Liens in favor of or for the benefit of the
               Issuing Bank in or upon cash, cash equivalents or
               other liquid assets pledged to the Issuing Bank in
               connection with, or in or upon bills of lading or
               other shipping or transportation documents,
               warehouse receipts or similar rights arising in
               connection with, the L/C Agreements or the
               issuance and payment of drawings under Letters of
               Credit.

               (8)  Liens in favor of or for the benefit of the
               Agent or any Lender in or upon cash, cash
               equivalents, marketable securities or other liquid
               assets and other rights relating to or in
               connection with overnight investments or other
               investments made or managed by Agent or any Lender
               for or on behalf of the Borrower, any of its
               Subsidiaries or Symtron."

          Section 3.     Section 7. Definitions.  Section 7 of the Guaranty
                         ----------------------
     Agreement is amended in its entirety as follows:

          ""Subsidiaries" of Guarantor means AAI Corporation, a
          Maryland corporation; Detroit Stoker Company, a Michigan
          corporation; Neo Products Co., an Illinois corporation;
          U.I.C.-Del. Corporation, a Delaware corporation; and Symtron
          Systems, Inc., a New Jersey corporation."





























     



     

          Section 4.     No Other Amendment. Except as specifically amended
                         ------------------
     herein, the Guaranty Agreement shall remain in full force and effect
     in accordance with its terms.

          Section 5.     Governing Law. This Amendment No. 2 shall be
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     governed by and construed in accordance with the laws of the State of
     New York.

          Section 6.     Counterparts.  This Amendment No. 2 may be
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     executed in any number of counterparts and by different parties hereto
     in separate counterparts, each of which when so executed shall be
     deemed to be an original and all of which taken together shall
     constitute one and the same agreement.

          IN WITNESS WHEREOF, the parties hereto have caused this Amendment
     No. 2 to be executed by their respective officers thereunto duly
     authorized as of the date above first written.

                              UNITED INDUSTRIAL CORPORATION            




                              By:                           
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                              Name: Howard Bloch            
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                              Title: Vice President         
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                              PRINCIPAL MUTUAL LIFE INSURANCE COMPANY


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                              THE TRAVELERS INSURANCE COMPANY




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