Document:

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                                                                   EXHIBIT 10.52
                                                                   -------------

                      SECURED NON-RECOURSE PROMISSORY NOTE
                      ------------------------------------

March 2, 1999                                                      $822,441

     FOR VALUE RECEIVED, Edward M.  Kopko, an individual whose place of business
is 110 Summit Avenue, Montvale, NJ 07645 ("Payor"), hereby promises to pay to
Butler International, Inc., a Maryland corporation ("Payee" or the "Company"),
or its assigns, the principal amount of eight hundred twenty-two thousand, four
hundred forty-one dollars exactly ($822,441).  Certain capitalized terms used in
this Secured Non-Recourse Promissory Note (the "Note") are defined in Section 3
below.

     This Note is being made by Payor in order to enable Payor to meet his tax
obligation, including statutory withholding taxes, on Payor's purchase of
125,000 shares of common stock, par value $.001 per share, of the Company (the
"Common Stock") from the Company pursuant to a stock option granted by the Payor
to the Company on July 16, 1996.

     1.  Payment of Note.

     (a) Maturity Date.  Except as otherwise provided herein, the entire unpaid
principal balance of this Note (together with interest accrued thereon) shall
become due and payable on the seventh anniversary of the date of this Note (the
"Maturity Date");

     (b) Interest.  No interest shall accrue on this Note; and

     (c) Non-Recourse Obligations.  Notwithstanding anything to the contrary
stated herein, Payee agrees that for payment of this Note it will look solely
tot he Pledged Collateral or such other collateral, if any, it may now or
hereafter be given to secure the payment of this Note, and no other assets of
Payor shall be subject to levy, execution or other enforcement procedure for the
satisfaction of the remedies of Payee, or for any payment required to be made
under this Note.

     (d) Forgiveness Upon Change in Control or Other Circumstances.  The Payor's
obligations under this Note to pay the Company the principal amount due
hereunder shall be forgiven and deemed to have been discharged in its entirety
in the event one of the following occurs prior to the Maturity Date, and
provided the Payor continues to hold office as a director of the Company through
such time:

          (1)  if Payor runs for re-election as director but is not re-elected;
          (2)  the disability of the Payor;
          (3)  the death of the Payor; or
          (4)  a "Change in Control" of the Company.

     For purposes of this Note, a "Change in Control" shall have the definition
set forth in that certain Amended and Restated Employment Agreement, dated as of
July 11, 1994 and effective as of January 1, 1991 among Payor and the Company.

     2.  Events of Default.

     (a) Definition.  For purposes of this Note, an Event of Default shall be
deemed to have occurred if:

          (i) Payor fails to pay when due any amount (whether interest,
     principal or other amount) then due or payable on this Note for a period of
     thirty (30) days after the holder of this Note notifies Payor of such
     failure;

          (ii) Payor fails to perform or observe any other provision contained
     in this Note or the Stock Pledge Agreement and such failure continues
     unremedied for a period of thirty (30) days after the holder of this Note
     notifies Payor of such breach; or

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          (iii)  Payor makes an assignment for the benefit of creditors or
     admits in writing his inability to pay his debts generally as they become
     due; or an order, judgment or decree is entered adjudicating Payor bankrupt
     or insolvent; or any order for relief with respect to Payor is entered
     under the Bankruptcy Code; or Payor petitions or applies to any tribunal
     for the appointment of a custodian, trustee, receiver or liquidator, or
     commences any proceeding relating to himself under any bankruptcy,
     reorganization, arrangement, insolvency, readjustment of debt, dissolution
     or liquidation law of any jurisdiction; or any such petition or application
     is filed, or any such proceeding is commenced, against Payor and either (a)
     Payor in writing indicates his approval thereof, consents thereto or
     acquiesces therein or (b) such petition, application or proceeding is not
     dismissed within ninety (90) days.

     (b)  Consequences of Default.

          (i) If any Event of Default (other than the type described in
     paragraph 2(a)(iii) hereof) has occurred, the holder of this Note may
     demand (by written notice delivered to Payor) immediate payment of all or
     any portion of the outstanding principal amount of this Note, which amount
     shall become due and payable upon such demand.  If an Event of Default of
     the type described in paragraph 3(a)(iii) has occurred, than all of the
     outstanding principal amount of this Note shall automatically be
     immediately due and payable without any action on the part of the holder of
     this Note.

          (ii) Each holder of this Note shall also have any other rights which
     such holder may have been afforded under this Note or the Stock Pledge
     Agreement at any time and any other rights which such holder may have
     pursuant to applicable law.

     3.  Certain Defined Terms.  As used in this Note, the following terms shall
have the following meanings:

          "Bankruptcy Code" means the Bankruptcy Code of 1978, as amended.

          "Pledged Collateral" means the Common Stock pledged by Payor under the
     Stock Pledge Agreement as security for Payor's performance of this
     obligation under this Note.

"Stock Pledge Agreement" means the Stock Pledge Agreement dated the date hereof
between Payor and the Company.

     4.  Amendment and Waiver.  Except as otherwise expressly provided herein,
the provisions of this Note may note be amended and Payor may not take any
action prohibited herein, or omit to perform any act required to be performed by
him herein, unless Payor has obtained the prior written consent of the holder of
this Note.

     5.  Cancellation.  After all obligations for the payment of money arising
under this Note have been paid in full, this Note will be surrendered to Payor
for cancellation.

     6.  Notices; Place of Payment.  Any notice hereunder shall be in writing
and shall be delivered by recognized courier, facsimile or certified mail,
return receipt requested, and shall be conclusively deemed to have been received
by a party hereto and to be effective on the day on which delivered or
facsimiled to such party at its address set forth below (or at such other
address as such party shall specify in writing):

          If to Payor:  Edward M.  Kopko
                         110 Summit Avenue
                         Montvale, New Jersey 07645

          If to Payee:  Butler International, Inc.
                         110 Summit Avenue

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                         Montvale, New Jersey 07645
                         Attn: Chief Financial Officer

     All payments to be made under this Note are to be delivered to the holder
at such address or to the attention of such person as the holder may designate
by prior written notice to Payor.  At the request of the holder of this Note,
all payments shall be made by wire transfer of immediately available funds to an
account which the holder may designate from time to time.

     7.  Waiver of Presentment, Demand, Dishonor.

     (a) Payor hereby waives presentment for payment, protest, demand, notice of
protest, notice of nonpayment and diligence with respect to this Note, and
waives and renounces all rights to the benefits of any statute of limitations or
any moratorium, appraisement, exemption, or homestead now provided or that
hereafter may be provided or allowed under the Bankruptcy Code, both as to
himself and as to all of his property, whether real or personal, against the
enforcement and collection of the obligations evidenced by this Note and any and
all extensions, renewals and modifications hereof.

     (b) No failure on the part of any holder of this Note to exercise any right
or remedy hereunder with respect to Payor, whether before or after the happening
of an Event of Default, shall constitute waiver of any such Event of Default or
of any other event of Default by such holder or on behalf of any other holder.
No failure to accelerate the debt of Payor evidenced hereby by reason of an
Event of Default or indulgence granted from time to time shall be construed to
be a waiver of the right to insist upon prompt payment thereafter, or shall be
deemed to be a novation of this Note or a reinstatement of such debt evidenced
hereby or a waiver of such right of acceleration or any other right, or be
construed so as to preclude the exercise of any right any holder of this Note
may have, whether by the laws of the state governing this Note, by agreement or
otherwise, and Payor hereby expressly waives the benefit of any statute or rule
of law or equity that would produce a result contrary to or in conflict with the
foregoing.

     8.  Governing Law.  the validity, construction and interpretation of this
Note shall be governed by and construed in accordance with the internal laws of
the State of New Jersey.

     9.  Transfer; Assignment.  This Note may not be negotiated, assigned or
transferred by Payor at any time, except with Payee's prior written consent.
This Note may not be negotiated, assigned or transferred by Payee except in
connection with the sale of all or substantially all of Payee's assets.

     10. Entire Agreement.  This Secured Non-Recourse Promissory Note and the
Stock Pledge Agreement contain the entire agreement of the parties and
supersedes all other agreements, understandings and representations, oral or
otherwise, between the parties with respect to the matters contained herein.
This Agreement shall be binding upon and shall inure to the benefit of the
parties hereto and their respective successors, assigns, heirs, administrators,
fiduciaries, next of kin and executors.  Section headings used herein are for
convenience only and shall not affect the meaning or construction of any of the
provisions hereof.  This Agreement may be executed in any number of counterparts
with the same effect as if the signatures thereto and hereto were upon the same
instrument.

     IN WITNESS WHEREOF, Payor has executed and delivered this Secured Non-
Recourse Promissory Note on the date first written above.

                                          /s/ Edward M. Kopko
                                          -------------------------------
                                          Edward M.  Kopko

                                       3<PAGE>

                                THIRD AMENDMENT
                                ---------------

     THIS THIRD AMENDMENT dated as of December 15, 1999 (this "Amendment")
amends the Credit Agreement dated as of September 29, 1998 (as previously
amended, the "Credit Agreement") among United Rentals (North America), Inc. (the
"Company"), United Rentals, Inc. ("Parent"), United Rentals of Canada, Inc.,
various financial institutions, Bank of America Canada, as Canadian Agent, and
Bank of America, N.A. (formerly known as Bank of America National Trust and
Savings Association), as U.S. Agent.  Terms defined in the Credit Agreement are,
unless otherwise defined herein or the context otherwise requires, used herein
as defined therein.

     WHEREAS, the parties hereto desire to increase the availability of Letters
of Credit under the Credit Agreement;

     NOW, THEREFORE, the parties hereto agree as follows:

     SECTION 1  Amendments.  Effective on (and subject to the occurrence of) the
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Amendment Effective Date (as defined below), Section 2.1.4 of the Credit
Agreement shall be amended by deleting the reference to "U.S. $25,000,000"
therein and substituting "U.S. $50,000,000" therefor.

     SECTION 2  Representations and Warranties.  Parent and the Company
                ------------------------------
represent and warrant to the Agents and the Banks that (a) each of the
representations and warranties made by Parent and the Company in Section 9
(excluding Section 9.8) of the Credit Agreement, as amended hereby (as so
amended, the "Amended Agreement"), is true and correct as of the date hereof,
with the same effect as if made on such date, and (b) no Event of Default or
Unmatured Event of Default has occurred or is continuing.

     SECTION 3  Effectiveness.  The amendment set forth in Section 1 above shall
                -------------                              ---------
become effective on the date (the "Amendment Effective Date") when the U.S.
Agent shall have received counterparts hereof executed by the Company, Parent,
the Required Banks and the U.S. Agent.

     SECTION 4  Miscellaneous.
                -------------

     4.1  Continuing Effectiveness, etc. As herein amended, the Credit Agreement
          ------------------------------
shall remain in full force and effect and is hereby ratified and confirmed in
all respects.  After the Amendment Effective Date, all references in the Credit
Agreement and the other Loan Documents to the "Credit Agreement" or similar
terms shall refer to the Amended Agreement.

     4.2  Counterparts.  This Amendment may be executed in any number of
          ------------
counterparts and by the different parties on separate counterparts, and each
such counterpart shall be deemed to be an original but all such counterparts
shall together constitute one and the same agreement.
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     4.3  Expenses.  The Company agrees to pay all reasonable expenses of the
          --------
U.S. Agent, including reasonable fees and charges of counsel for the U.S. Agent,
in connection with the preparation, execution and delivery of this Amendment.

     4.4  Governing Law.  This Amendment shall be construed in accordance with
          -------------
and governed by the substantive laws of the State of Illinois applicable to
contracts made and to be performed entirely within such State.

     4.5  Successors and Assigns.  This Amendment shall be binding upon Parent,
          ----------------------
the Company, the Banks and the Agents and their respective successors and
assigns, and shall inure to the benefit of Parent, the Company, the Banks and
the Agents and the respective successors and assigns of the Banks and the
Agents.

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   Delivered at Chicago, Illinois, as of the day and year first above written.

                             UNITED RENTALS, INC.

                             By___________________________________________
                               Chief Financial Officer

                             UNITED RENTALS (NORTH AMERICA),
                             INC.

                             By___________________________________________
                               Chief Financial Officer

                             BANK OF AMERICA N.A., as U.S. Agent

                             By___________________________________________
                             Title________________________________________

                             BANK OF AMERICA N.A., as a U.S. Bank, as Issuing
                             Bank and as Swing Line Bank

                             By___________________________________________
                             Title________________________________________

                             BANK OF AUSTRIA CREDITANSTALT

                             By___________________________________________
                             Title________________________________________

                                      S-1
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                             THE BANK OF NEW YORK, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             CREDIT LYONNAIS NEW YORK BRANCH, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             DEUTSCHE BANK AG, New York Branch and/or Cayman
                             Islands Branch, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             By___________________________________________
                             Title________________________________________

                             ALLFIRST BANK, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             SUMMIT BANK, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                                      S-2
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                             NATIONAL CITY BANK, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             BANKBOSTON, N.A., as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             COMERICA BANK, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             FLEET BANK, N.A., as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             HARRIS TRUST AND SAVINGS BANK, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             THE BANK OF NOVA SCOTIA, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                                      S-3
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                             UNION BANK OF CALIFORNIA, N.A., as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             CIBC INC., as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             LASALLE BANK NATIONAL
                             ASSOCIATION, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             CITICORP DEL-LEASE, INC., as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             ERSTE BANK DER OESTERREICHISCHEN SPARKASSEN AG-NEW
                             YORK, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                                      S-4
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                             CITY NATIONAL BANK, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             FUJI BANK, LIMITED, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             BANKERS TRUST COMPANY, as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                             WELLS FARGO BANK, N.A., as a U.S. Bank

                             By___________________________________________
                             Title________________________________________

                                      S-5

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