<PAGE>

                                                                    EXHIBIT 10.4

                          AMENDMENT NO. 7 AND CONSENT

                           Dated as of May 23, 2001

                                      to

                 FOURTH AMENDED AND RESTATED CREDIT AGREEMENT

                           Dated as of May 31, 2000

          This Amendment No. 7 and Consent (the "Amendment") dated as of May 23,
2001 is entered into among AVIATION SALES DISTRIBUTION SERVICES COMPANY, a
Delaware corporation ("Distribution"), AEROCELL STRUCTURES, INC., an Arkansas
corporation ("Aerocell"), AVS/M-2, INC. (formerly known as AVS/Kratz-Wilde
Machine Company), a Delaware corporation ("Kratz-Wilde"), WHITEHALL CORPORATION,
a Delaware corporation ("Whitehall"), TRIAD INTERNATIONAL MAINTENANCE
CORPORATION, a Delaware corporation ("TIMCO"), AVS/M-3, INC. (formerly Apex
Manufacturing, Inc.), an Arizona corporation ("Apex"), CARIBE AVIATION, INC., a
Florida corporation ("Caribe"), AIRCRAFT INTERIOR DESIGN, INC., a Florida
corporation ("Design"), AVIATION SALES LEASING COMPANY, a Delaware corporation
("Leasing"), and TIMCO ENGINE CENTER, INC., a Delaware corporation ("TIMCO
Engine") (Distribution, Aerocell, Kratz-Wilde, Whitehall, TIMCO, Apex, Caribe,
Design, Leasing, and TIMCO Engine being collectively referred to as the
"Borrowers"), and AVIATION SALES COMPANY, a Delaware corporation ("Parent"),
AERO HUSHKIT CORPORATION, a Delaware corporation ("Hushkit"), AVIATION SALES
PROPERTY MANAGEMENT CORP., a Delaware corporation ("Property Management"),
AVIATION SALES SPS I, INC., a Delaware corporation ("SPS I"), AVS/M-1, INC.
(formerly Aviation Sales Manufacturing Company), a Delaware corporation
("Manufacturing"), AVSRE, L.P., a Delaware limited partnership ("AVSRE"),
AVIATION SALES FINANCE COMPANY, a Delaware corporation ("Finance"),
HYDROSCIENCE, INC., a Texas corporation ("Hydroscience"), AVIATION SALES
MAINTENANCE, REPAIR & OVERHAUL, INC., a Delaware corporation ("MR&O") and TIMCO
ENGINEERED SYSTEMS, INC., a Delaware corporation ("Engineered Systems") (Parent,
Hushkit, Property Management, SPS I, Manufacturing, AVSRE, Finance,
Hydroscience, MR&O and Engineered Systems being collectively referred to as the
"Guarantors"), and the "Lenders" (as defined in the Credit Agreement identified
below) a party hereto. Capitalized terms used herein without definition are
used herein as defined in the Credit Agreement.

                            PRELIMINARY STATEMENT:

          WHEREAS, Borrowers, Parent, Citicorp USA, Inc., as Agent, and certain
financial institutions, as Lenders and Issuing Banks, are parties to that
certain Fourth Amended and Restated Credit Agreement dated as of May 31, 2000,
as heretofore amended (the "Credit Agreement");
<PAGE>

          WHEREAS, the Parent and Caribe have informed the Lenders of a delay in
the anticipated closing of the "Caribe Sale" (as described in that certain
Amendment No. 6 and Consent dated as of May 21, 2001, executed and delivered in
connection with the Credit Agreement) beyond May 23, 2001;

          WHEREAS, certain provisions of the aforesaid Amendment No. 6 and
Consent were to have become effective only upon the consummation of the Caribe
Sale, the Borrowers have requested that certain of such provisions become
effective notwithstanding the delay in the Caribe Sale closing subject to the
terms set forth in this Amendment; and

          WHEREAS, the parties hereto have agreed to amend the Credit Agreement
on the terms and conditions set forth herein;

          NOW, THEREFORE, the parties hereto hereby agree as follows:

          SECTION 1.  Amendments to the Credit Agreement.
                      ----------------------------------

     1.1  Effective as of May 23, 2001, subject to the satisfaction of the
conditions precedent set forth in Section 3 hereof, the Credit Agreement is
                                  ---------
hereby amended as follows:

          1.1.1 Section 1.01 is amended to add the following definitions to
                ------------
Section 1.01:
------------

     "Amendment No. 6" means that certain Amendment No. 6 and Consent dated as
      ---------------
of May 21, 2001 executed and delivered in connection with this Agreement.

     "Caribe Sale" means the sale by Caribe to Hamilton Sundstrand Service
      -----------
Corporation (the "Buyer") of substantially all of its Property pursuant to, and
as more particularly described in, the terms of that certain Asset Purchase
Agreement by and among Parent, Caribe and the Buyer (the "Asset Purchase
Agreement"), a copy of which Asset Purchase Agreement has been delivered to the
Agent and Lenders.

     "Disputed Receivable" means that certain Receivable identified on Schedule
      -------------------                                              --------
1 attached to Amendment No. 6.
-

          1.1.2  Section 1.01 is amended to add the following provision at the
                 ------------
end of the definition of "Borrowing Base" therein:

     Notwithstanding its not being an Eligible Receivable solely due to its not
meeting the criteria set forth in clause (iv) or clause (viii) of the definition
of "Eligible Receivable", the Disputed Receivable shall be included in the
Borrowing Base for purposes of calculating Revolving Credit Availability in an
original amount of $2,301,961; provided that (i) so long as the Disputed
                               -------- ----
Receivable is subject to dispute, the amount of Revolving Credit Availability
attributable to the Disputed Receivable shall be reduced by $230,196.10  as of
Friday of each calendar week during the period commencing on May 25, 2001 and
ending on July 27, 2001 and (ii) in the event the Caribe Sale is not consummated
by June 1, 2001, the Disputed Receivable shall not be included in the Borrowing
Base as aforesaid after June 1, 2001. In the event the

                                       2
<PAGE>

Disputed Receivable is otherwise not an Eligible Receivable, it shall not be
included in determination of the Borrowing Base.

     1.2  Effective as of the date on which the Caribe Sale is consummated,
subject to the satisfaction of the conditions precedent set forth in Section 3
                                                                     ---------
hereof, the Credit Agreement is hereby amended as follows:

          1.2.1  Section 1.01 is amended to (a) delete the definitions of
                 ------------
"Interest Reserve" and "Revolving Credit Commitments" (as part of the
definition of "Revolving Credit Commitment") therein and substitute the
following therefor:

     "Interest Reserve" means $100,000.
      ----------------

     "Revolving Credit Commitments" means the aggregate principal amount of the
      ----------------------------
Revolving Credit Commitments of all the Lenders, the maximum amount of which
shall be $60,000,000 (after giving effect to the Caribe Sale), as reduced from
time to time pursuant to Section 4.01.
                         ------------

          1.2.2  The provisions of Article XI are deleted in their entirety and
                                   ----------
the following is substituted therefor:

                                   ARTICLE XI
                              FINANCIAL COVENANTS

            The Parent covenants and agrees that so long as any Revolving Credit
Commitments are outstanding and thereafter until payment in full of all of the
Obligations (other than indemnities not yet due):

     11.01  Minimum EBITDA.  The Parent shall maintain a positive EBITDA,
            --------------
determined as of the last day of each Fiscal Quarter for the Fiscal Quarter then
ending, during the period commencing with June 30, 2001 and ending on June 30,
2002.

     11.02  Capital Expenditures.  The Parent and its Subsidiaries shall not
            --------------------
make Capital Expenditures in the aggregate during any period set forth below in
excess of the amount set forth below opposite such period; (in each instance,
the "Maximum Amount"):

<TABLE>
<CAPTION>
Determination Date         Applicable Period                                       Maximum Amount
------------------         -----------------                                       --------------
<S>                        <C>                                                     <C>
March 31, 2001             Fiscal Quarter then ending                              $1,799,000
June 30, 2001              Two Fiscal Quarter period then ending                   $2,991,000
September 30, 2001         Three Fiscal Quarter period then ending                 $4,183,000
December 31, 2001          Four Fiscal Quarter period then ending                  $5,375,000
March 31, 2002             Four Fiscal Quarter period then ending                  $5,375,000
June 30, 2002              Four Fiscal Quarter period then ending                  $5,375,000
</TABLE>

                                       3
<PAGE>

     provided, however, to the extent the Parent and its Subsidiaries have not
     --------  -------
made Capital Expenditures in the amount permitted above for any given period set
forth above, Capital Expenditures in an amount equal to 100% of the Maximum
Amount of such Capital Expenditures permitted but not made in such period may be
made in the immediately next succeeding period in addition to any amounts
permitted above for such succeeding period; provided that to the extent amounts
                                            -------- ----
carried forward from one period to the next succeeding period are not expended
in such period, such surplus may not be carried forward to any other succeeding
period.

     11.03  Parent and Subsidiaries.  For purposes of the covenants set forth in
            -----------------------
this Article XI, references to Parent and its Subsidiaries shall be deemed to
     ----------
mean Parent and its Subsidiaries on a consolidated basis.

            1.2.3  Section 12.01 is amended to insert at the end thereof the
                   -------------
following provision as clause (q) thereof:
                       ----------

     (q)  Liquidity.  As of the day immediately preceding the day on which any
          ---------
     payment of the Parent's obligations under the Senior Subordinated Notes is
     to be made (whether then due or not due), after giving effect to the
     Obligations outstanding as of the close of business of the Agent on such
     preceding day, (A) the Revolving Credit Availability is not greater than
     $10,000,000 and (B) the accounts payable of the Borrowers (exclusive of (1)
     accounts payable for the businesses sold to KAV Inventory, LLC and
     Kellstrom Industries, Inc. carried on the books of Distribution as of the
     date of consummation of such sales and (2) accounts payable by the
     Borrowers for professional services) is not less than $17,000,000 in the
     aggregate.

            SECTION 2.  Consent and Direction. Effective upon the satisfaction
                        ---------------------
of the conditions precedent set forth in Section 3 hereof, the Lenders hereby:
                                         ---------

            2.1  consent to the following:

            (a)  the Caribe Sale ; provided that the cash proceeds thereof
                                   -------- ----
received upon consummation of the Caribe Sale are used for the purposes set
forth on Exhibit A attached hereto and made a part hereof and any cash proceeds
         ---------
thereof received after consummation of the Caribe Sale under Section 4.2(b) of
the Asset Purchase Agreement retained by Caribe as set forth on Exhibit A shall
                                                                ---------
be deemed applied as part of the $10,000,000 permitted to be retained by the
Borrowers under the "fourth" application described in Section 4.01(b)(ix)(A)
                                                      ----------------------
unless $10,000,000 of Net Cash Proceeds of Sale from Designated Asset Sales has
theretofore been so applied, in which case such Net Cash Proceeds received after
consummation of the Caribe Sale shall be applied as required by Section
                                                                -------
4.01(b)(ix);
------------

            (b)  the incurrence by Parent of the Accommodation Obligation in
favor of the Buyer under Section 15.14 of the Asset Purchase Agreement;

            (c)  the terms of that certain Amendment and Consent Agreement No. 9
for Lease Agreement and Certain Other Operative Agreements dated as of May 21,
2001 and that certain

                                       4
<PAGE>

Amendment and Consent Agreement No. 10 for Lease Agreement and Certain Other
Operative Agreements dated as of May 24, 2001, pursuant to which the TROL
Documents are amended and the matters referenced in this Section 2.1 and Section
                                                         -----------     -------
2.2 below are consented ( collectively, the "TROL Amendment"), a copy of which
---
has been delivered to the Agent; and

          (d)  the change of the name of Caribe to AVS/CAI, Inc. substantially
concurrently with the closing of the Caribe Sale;

          2.2  agree, concurrently with the amendments set forth in Section 1.2
                                                                    -----------
becoming effective, that the $13,000,000 reserve applied against the Revolving
Credit Commitments pursuant to condition (13) of that certain Consent and Waiver
dated December 20, 2000 shall be eliminated; and

          2.3  authorize and direct the Agent to execute and deliver a release
letter in the form attached hereto as Exhibit B and made a part hereof and the
                                      ---------
release documents referenced therein evidencing the releases referenced in such
release letter with respect to the Caribe Sale.

          SECTION 3.  Conditions Precedent.  This Amendment shall become
                      --------------------
effective, if, and only if:

          3.1  the Agent shall have received on or before May 24, 2001:

     (a)  a facsimile or original executed copy of this Amendment executed by
     the Parent, each Borrower, the Guarantors and the Super-Majority Lenders;

     (b)  an opinion of counsel to the Borrowers and Guarantors with respect to
     non-contravention of the TROL Documents and agreements under which the
     Senior Subordinated Notes have been issued, this Amendment and the
     instruments and documents executed by the Borrowers and Guarantors in
     connection herewith, and the  Caribe Sale;

     (c)  corporate resolutions of the Parent, Borrowers and Guarantors
     authorizing the execution and delivery of this Amendment and all
     instruments and documents required to be executed and delivered in
     connection herewith;

     (d)  the written consent of the obligee parties to the TROL Documents to
     the terms of this Amendment; and

     (e)  an executed copy of the TROL Amendment.

               3.2 with respect to the amendments set forth in Section 1.2 of
                                                               -----------
     this Amendment and the agreement set forth in Section 2.2 of this
                                                   -----------
     Amendment, the Agent shall have received on the date the Caribe Sale is
     consummated, which date shall not be later than June 1, 2001:

     (a)  confirmation that the Asset Purchase Agreement relating to the Caribe
     Sale shall not have been modified in any substantive manner, as determined
     by the Agent, from the

                                       5
<PAGE>

     May 18, 2001 draft provided to the Agent and Lenders, without the written
     concurrence of the Agent;

     (b)  the written direction of the Parent and Caribe to the trustee under
     the TROL Documents with respect to execution and delivery of transfer
     documents effecting the sale of the Caribe TROL Property;

     (c)  confirmation that the Caribe Sale has been consummated and that the
     cash proceeds of the Caribe Sale received upon consummation have been used
     as set forth on Exhibit A;
                     ---------

     (d)  a Borrowing Base Certificate as of the date on which the Caribe Sale
     is consummated, after giving effect to this Amendment and the Caribe Sale.

          3.3  after giving effect to this Amendment, no "Event of Default"
shall have occurred and be continuing under the terms of the Credit Agreement,
TROL Documents, Indenture under which the Senior Subordinated Notes have been
issued, or BofA Note, in each instance, as amended or supplemented through the
date of this Amendment, and no "Change of Control" (as defined in such
Indenture) shall have occurred.

          SECTION 4.  Representations and Warranties; Acknowledgment.  The
                      ----------------------------------------------
Borrowers hereby represent and warrant as follows:

          4.1  This Amendment and the Credit Agreement as previously executed
and delivered and as amended hereby constitute legal, valid and binding
obligations of the Borrowers and are enforceable against the Borrowers in
accordance with their terms.

          4.2  After giving effect to this Amendment, no Event of Default or
Potential Event of Default exists or would result from any of the transactions
contemplated by this Amendment. No event of default or default has occurred and
is continuing under the terms of (a) any of the TROL Documents, (b) under any of
the agreements and documents executed with respect to the Senior Subordinated
Notes or under which the Senior Subordinated Notes have been issued, or (c)
under any of the agreements and documents executed with respect to the BofA
Note.

          4.3  Upon the effectiveness of this Amendment, Parent and each of the
Borrowers hereby reaffirm all covenants, representations and warranties made by
it, respectively, in the Credit Agreement to the extent the same are not amended
hereby and agree that all such covenants, representations and warranties shall
be deemed to have been remade as of the date this Amendment becomes effective
(unless a representation and warranty is stated to be given on and as of a
specific date, in which case such representation and warranty shall be true,
correct and complete as of such date).

          SECTION 5.  Reference to and Effect on the Credit Agreement;
Reaffirmation.

          5.1  Upon the effectiveness of this Amendment, each reference in the
Credit Agreement to "this Agreement", "hereunder", "hereof", "herein" or words
of like import shall mean and be a reference to the Credit Agreement, as amended
hereby, each reference to the Credit Agreement in any other document, instrument
or agreement executed and/or delivered in

                                       6
<PAGE>

connection with the Credit Agreement shall mean and be a reference to the Credit
Agreement as amended hereby.

          5.2  Except as specifically amended or agreed above, the Credit
Agreement, the Notes and all other Loan Documents shall remain in full force and
effect and are hereby ratified and confirmed.

          5.3  The execution, delivery and effectiveness of this Amendment shall
not operate as a waiver of any right, power or remedy of any Lender or Issuing
Bank or the Agent under the Credit Agreement, the Notes or any of the other Loan
Documents, nor constitute a waiver of any provision contained therein, except as
specifically set forth herein.

          5.4  Each of the Borrowers and Guarantors hereby (i) reaffirms all of
its obligations and liabilities under the respective security agreements, pledge
agreements and other Loan Documents, including, without limitation, the
Collateral Documents Amendment, pursuant to which any Lien against property and
interests in property of such Person has been granted, and the Release Agreement
dated as of February 14, 2001,  which have been heretofore executed by such
Person in favor of the Agent for the benefit of the Holders (including, without
limitation, the holder of the Supplemental Term Loan Note) and (ii) acknowledges
and agrees that such security agreements, pledge agreements and other Loan
Documents remain in full force and effect, before and after giving effect to the
Amendment, for the benefit of the Agent and such other Holders, that the
security granted thereunder shall continue as security for the Obligations and
the Indebtedness evidenced by the Supplemental Term Loan Note, and that the
"Borrower Claims" described in such Release Agreement shall mean and extend to
the matters described therein whether existing, held or alleged heretofore or as
of the date of this Amendment, and which could, might or may be claimed to exist
through the date of this Amendment.

          5.5  Each of Parent and the other Guarantors agrees that it continues
to be liable, as a guarantor under the Loan Documents heretofore executed and
delivered thereby of the payment and performance of the Obligations and the
Indebtedness evidenced by the Supplemental Term Loan Note, whether incurred
prior to or after the effective date of the Amendment

          SECTION 6.  Execution in Counterparts.  This Amendment may be executed
                      -------------------------
in any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed and delivered shall be deemed to be
an original and all of which taken together shall constitute but one and the
same instrument. Delivery of an executed counterpart of this Amendment by
telecopier shall be effective as delivery of a manually executed counterpart of
this Amendment.

          SECTION 7.  Governing Law.  This Amendment shall be governed by and
                      -------------
construed in accordance with the laws of the State of New York.

          SECTION 8.  Headings.  Section headings in this Amendment are included
                      --------
herein for convenience of reference only and shall not constitute a part of this
Amendment for any other purpose.

                 [Remainder of Page Intentionally Left Blank]

                                       7
<PAGE>

          IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be executed by their respective officers thereunto duly authorized as of the
date first above written.

CITICORP USA, INC.              HELLER FINANCIAL, INC.

/s/ Gregory W. Frewzel          By /s/ Albert J. Forzano
--------------------------        --------------------------
 Name: Gregory W. Frewzel        Name: Albert J. Forzano
 Title: Vice President           Title: Vice President


FIRST UNION COMMERCIAL          SALOMON BROTHERS HOLDING
 CORPORATION                    COMPANY, INC.

By /s/ Ron R. Ferguson          By /s/ John Humphrey
  ---------------------------     --------------------------
 Name: Ron R. Ferguson           Name: John Humphrey
 Title: Senior Vice President    Title: Managing Director


NATIONAL CITY COMMERCIAL        ARK CLO 2000-I, LIMITED
FINANCE, INC.                   By: Patriarch Partners, LLC, as
                                    Attorney-in-Fact
                                By: LD Investments LLC, as Manager

By /s/ Kathryn C. Ellero        By  /s/
  --------------------------      ---------------------------
 Name: /s/ Kathryn C. Ellero     Name:
 Title: Vice President           Title:


THE INTERNATIONAL BANK OF       BANK OF AMERICA, N.A.
MIAMI, N.A.


By /s/ Caridad C. Errazquin     By /s/ Jeff Strickland
  --------------------------      ---------------------------
 Caridad C. Errazquin            Name: Jeff Strickland
 Vice President                  Title: Vice President
 Trade Finance Division

                                                                Signature Page 1
<PAGE>

FIRSTAR BANK, N.A.               CITIZENS BUSINESS CREDIT
                                  COMPANY


By_________________________      By_________________________
 Name:                            Name:
 Assistant Vice President         Vice President



AMSOUTH BANK                     PNC BANK NATIONAL ASSOCIATION


By /s/ Patrick R. Brocker        By /s/ Ryan Peak
  -------------------------        -------------------------
 Name: Patrick R. Brocker         Name: Ryan Peak
 Title: Attorney-in-Fact          Title: Vice President

                                                               Signature Page 2
<PAGE>

AVIATION SALES DISTRIBUTION      AEROCELL STRUCTURES, INC.
 SERVICES COMPANY


By /s/ Michael C. Brant          By /s/ Michael C. Brant
  ---------------------------      ----------------------------
 Name: /s/ Michael C. Brant        Name /s/ Michael C. Brant
 Title: Vice President             Title: Vice President


AVS/M-2, INC.                    WHITEHALL CORPORATION


By /s/ Michael C. Brant          By /s/ Michael C. Brant
  ---------------------------      ----------------------------
 Name: Michael C. Brant            Name Michael C. Brant
 Title: Vice President             Title: Vice President


TRIAD INTERNATIONAL MAINTENANCE  AVS/M-3, INC.
 CORPORATION


By /s/ Michael C. Brant          By /s/ Michael C. Brant
  ---------------------------      ----------------------------
 Name: Michael C. Brant            Name Michael C. Brant
 Title: Vice President             Title: Vice President


AIRCRAFT INTERIOR DESIGN, INC.   CARIBE AVIATION, INC.


By /s/ Michael C. Brant          By /s/ Michael C. Brant
  ---------------------------      ----------------------------
 Name: Michael C. Brant            Name Michael C. Brant
 Title: Vice President             Title: Vice President


AVIATION SALES LEASING COMPANY   TIMCO ENGINE CENTER, INC.


By /s/ Michael C. Brant          By /s/ Michael C. Brant
  ---------------------------      ----------------------------
 Name: Michael C. Brant            Name Michael C. Brant
 Title: Vice President             Title: Vice President

                                                               Signature Page 3

<PAGE>

AERO HUSHKIT CORPORATION            AVIATION SALES PROPERTY
                                    MANAGEMENT CORP.


By /s/ Michael C. Brant             By /s/ Michael C. Brant
  ---------------------------         ----------------------------
 Name: Michael C. Brant               Name  Michael C. Brant
 Title: Vice President                Title: Vice President


AVIATION SALES COMPANY              AVIATION SALES SPS I, INC.


By /s/ Michael C. Brant             By: /s/ Michael C. Brant
  ---------------------------          ----------------------------
 Name:  Michael C. Brant               Name  Michael C. Brant
 Title: Vice President                 Title: Vice President


AVS/M-1, INC.                       AVSRE, L.P.
                                    By Aviation Sales Property
                                    Management Corp. as General
                                    Partner

By: /s/ Michael C. Brant
   --------------------------
   Name: Michael C. Brant
   Title: Vice President            By: /s/ Michael C. Brant
                                       ------------------------
                                       Name: Michael C. Brant
                                       Title: Vice President


AVIATION SALES FINANCE COMPANY      HYDROSCIENCE, INC.


By /s/ Michael C. Brant             By: /s/ Michael C. Brant
  ---------------------------          ----------------------------
 Name: Michael C. Brant                Name: Michael C. Brant
 Title: Vice President                 Title: Vice President

AVIATION SALES MAINTENANCE,
REPAIR & OVERHAUL, INC.             TIMCO ENGINEERED SYSTEMS, INC.


                                    By: /s/ Michael C. Brant
                                       ------------------------
By: /s/ Michael C. Brant               Name: Michael C. Brant
   --------------------------          Title: Vice President
   Name: Michael C. Brant
   Title: Vice President

                                                               Signature Page 4