<PAGE>

                            SUPPLEMENTAL INDENTURE                 EXHIBIT 4.1.3


         SUPPLEMENTAL INDENTURE (this "SUPPLEMENTAL INDENTURE"), dated as of
August 5, 1999 among CWP Acquisition, Inc., a Delaware corporation d/b/a/ Custom
Woodwork & Plastics, Inc. ("GUARANTOR"), a subsidiary of DeCrane Aircraft
Holdings, Inc. (or its permitted successor), a Delaware corporation (the
"ISSUER"), the other Guarantors (as defined in the Indenture referred to herein)
and State Street Bank and Trust Company, as trustee under the Indenture referred
to below (the "TRUSTEE").

                              W I T N E S S E T H

         WHEREAS, the Issuer has heretofore executed and delivered to the
Trustee an indenture (the "INDENTURE"), dated as of October 5, 1998 providing
for the issuance of an aggregate principal amount of up to $100.0 million of 12%
Senior Subordinated Notes due 2008 (the "NOTES");

         WHEREAS, the Indenture provides that under certain circumstances each
Guarantor shall execute and deliver to the Trustee a supplemental indenture,
pursuant to which the Guarantor shall unconditionally guarantee all of the
Issuer's Obligations under the Notes and the Indenture on the terms and
conditions set forth herein (the "NOTE GUARANTEE"); and

         WHEREAS, pursuant to Section 9.06 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

         NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, each
Guarantor and the Trustee mutually covenant and agree for the equal and ratable
benefit of the Holders of the Notes as follows:

         1. CAPITALIZED TERMS. Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

         2. AGREEMENT TO GUARANTEE. The Guarantor hereby agrees as follows:

         (a) Along with all Guarantors named in the Indenture, to jointly and
severally Guarantee to each Holder of a Note authenticated and delivered by the
Trustee and to the Trustee and its successors and assigns, irrespective of the
validity and enforceability of the Indenture, the Notes or the obligations of
Issuer hereunder or thereunder, that:

                  (i) the principal of and interest on the Notes will be
         promptly paid in full when due, whether at maturity, by acceleration,
         redemption or otherwise, and interest on the overdue principal of and
         interest on the Notes, if any, is lawful, and all other obligations of
         the Issuer to the Holders or the Trustee hereunder or thereunder will
         be promptly paid in full or performed, all in accordance with the terms
         hereof and thereof; and

                  (ii) in case of any extension of time of payment or renewal of
         any Notes or any of such other obligations, that same will be promptly
         paid in full when due or performed in accordance with the terms of the
         extension or renewal, whether at stated maturity, by acceleration or
         otherwise. Failing payment when due of any amount so guaranteed or any
         performance so guaranteed for whatever reason, the Guarantors shall be
         jointly and severally obligated to pay the same immediately.

         (b) The obligations hereunder shall be unconditional, irrespective of
the validity, regularity or enforceability of the Notes or the Indenture, the
absence of any action to enforce the


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same, any waiver or consent by any Holder of the Notes with respect to any
provisions hereof or thereof, the recovery of any judgment against Issuer,
any action to enforce the same or any other circumstance which might
otherwise constitute a legal or equitable discharge or defense of a guarantor.

         (c) The following is hereby waived: diligence, presentment, demand of
payment, filing of claims with a court in the event of insolvency or bankruptcy
of the Issuer, any right to require a proceeding first against the Issuer,
protest, notice and all demands whatsoever.

         (d) This Note Guarantee shall not be discharged except by complete
performance of the obligations contained in the Notes and the Indenture.

         (e) If any Holder or the Trustee is required by any court or otherwise
to return to the Issuer, the Guarantors, or any Custodian, trustee, liquidator
or other similar official acting in relation to either the Issuer or the
Guarantors, any amount paid by either to the Trustee or such Holder, this Note
Guarantee, to the extent theretofore discharged, shall be reinstated in full
force and effect.

         (f) The Guarantor shall not be entitled to any right of subrogation in
relation to the Holders in respect of any obligations guaranteed hereby until
payment in full of all obligations guaranteed hereby.

         (g) As between the Guarantors, on the one hand, and the Holders and the
Trustee, on the other hand, (x) the maturity of the obligations guaranteed
hereby may be accelerated as provided in Article 6 of the Indenture for the
purposes of this Note Guarantee, notwithstanding any stay, injunction or other
prohibition preventing such acceleration in respect of the obligations
guaranteed hereby, and (y) in the event of any declaration of acceleration of
such obligations as provided in Article 6 of the Indenture, such obligations
(whether or not due and payable) shall forthwith become due and payable by the
Guarantors for the purpose of this Note Guarantee.

         (h) The Guarantors shall have the right to seek contribution from any
non-paying Guarantor so long as the exercise of such right does not impair the
rights of the Holders under the Guarantee.

         (i) Pursuant to Section 11.03 of the Indenture, after giving effect to
any maximum amount and any other contingent and fixed liabilities that are
relevant under any applicable Bankruptcy or fraudulent conveyance laws, and
after giving effect to any collections from, rights to receive contribution from
or payments made by or on behalf of any other Guarantor in respect of the
obligations of such other Guarantor under Article 11 of the Indenture shall
result in the obligations of such Guarantor under its Note Guarantee not
constituting a fraudulent transfer or conveyance.

         3. EXECUTION AND DELIVERY. Each Guarantor agrees that the Note
Guarantees shall remain in full force and effect notwithstanding any failure to
endorse on each Note a notation of such Note Guarantee.

         4. GUARANTOR MAY CONSOLIDATE ETC. ON CERTAIN TERMS.

         (a) No Guarantor may consolidate with or merge with or into (whether or
not such Guarantor is the surviving Person), another corporation, Person or
entity whether or not affiliated with such Guarantor unless:

                  (i) subject to Section 5(a) hereof, the Person formed by or
         surviving any such consolidation or merger (if other than such
         Guarantor) assumes all the obligations of such Guarantor pursuant to a
         supplemental indenture in form and substance reasonably satisfactory to
         the Trustee, under the Notes, the Indenture and the Registration Rights
         Agreement;


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                  (ii) immediately after giving effect to such transaction, no
         Default or Event of Default exists; and

                  (iii) Issuer would, at the time of such transaction and after
         giving pro forma effect thereto and if such transaction had occurred at
         the beginning of the applicable four-quarter period, be permitted to
         incur at least $1.00 of additional Indebtedness pursuant to the Fixed
         Charger Coverage Ratio test set forth in Section 4.09 of the Indenture
         by virtue of Issuer's pro forma Cash Flow Coverage Ratio, immediately
         after giving effect to such transaction, to incur at least $1.00 of
         additional Indebtedness pursuant to the Cash Flow Coverage Ratio test
         set forth in Section 4.07 of the Indenture;

PROVIDED THAT, the requirements of clause (iii) of this Section 4(a) will not
apply in the case of a consolidation with or merger with or into the Issuer or
another Guarantor.

         (b) In case of any such consolidation, merger, sale or conveyance and
upon the assumption by the successor Person, by supplemental indenture executed
and delivered to the Trustee in the form of Exhibit E to the Indenture or
otherwise satisfactory in form to the Trustee, of the Note Guarantee and the due
and punctual performance of all of the covenants and conditions of the Indenture
to be performed by the Guarantor, such successor Person shall succeed to and be
substituted for the Guarantor with the same effect as if it had been named
herein as a Guarantor. All the Note Guarantees so issued shall in all respects
have the same legal rank and benefit under the Indenture as the Note Guarantees
theretofore and thereafter issued in accordance with the terms of the Indenture
as though all of such Note Guarantees had been issued at the date of the
execution hereof.

         (c) Except as set forth in Articles 4 and 5 of the Indenture, and
notwithstanding clauses (a) and (b) above, nothing contained in the Indenture or
in any of the Notes shall prevent any consolidation or merger of a Guarantor
with or into the Issuer or another Guarantor, or shall prevent any sale or
conveyance of the property of a Guarantor as an entirety or substantially as an
entirety to the Issuer or another Guarantor.

         5. RELEASES.

         (a) In the event of a sale or other disposition of all of the assets of
any Guarantor, by way of merger, consolidation or otherwise, or a sale or other
disposition of all of the capital stock of any Guarantor, such Guarantor (in the
event of a sale or other disposition, by way of such a merger, consolidation or
otherwise, of all of the capital stock of such Guarantor) or the corporation
acquiring the property (in the event of a sale or other disposition of all of
the assets of such Guarantor) will be released and relieved of any obligations
under its Note Guarantee; PROVIDED that the Net Proceeds of such sale or other
disposition are applied in accordance with the applicable provisions of the
Indenture, including without limitation Section 4.10 of the Indenture. Upon
delivery by the Issuer to the Trustee of an Officers' Certificate and an Opinion
of Counsel to the effect that such sale or other disposition was made by the
Issuer in accordance with the applicable provisions of the Indenture, including,
without limitation, Section 4.10 of the Indenture, the Trustee shall execute any
documents reasonably required in order to evidence the release of any Guarantor
from its obligations under its Note Guarantee.

         (b) Any Guarantor not released from its obligations under its Note
Guarantee shall remain liable for the full amount of principal of and interest
on the Notes and for the other obligations of any Guarantor under the Indenture
as provided in Article 11 of the Indenture.

         6. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder or agent of the Guarantor, as such,
shall have any liability for any obligations of the Issuer or any Guarantor
under the Notes, any Note Guarantees, the Indenture or this Supplemental
Indenture or for any claim based on, in respect of, or by reason of, such
obligations or their creation. Each Holder of the Notes by accepting a Note
waives and


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releases all such liability. The waiver and release are part of the
consideration for issuance of the Notes. Such waiver may not be effective to
waive liabilities under the federal securities laws and it is the view of the
Commission that such a waiver is against public policy.

         7. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK
SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE BUT WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

         8. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

         9. EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not affect the construction hereof.

         10. THE TRUSTEE. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture or for or in respect of the recitals contained herein, all of which
recitals are made solely by each Guarantor and the Issuer.

                                      SIGNATURES

       Dated as of August 5, 1999     DECRANE AIRCRAFT HOLDINGS, INC.



                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      AEROSPACE DISPLAY SYSTEMS, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:


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<PAGE>

                                      AUDIO INTERNATIONAL, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      AVTECH CORPORATION





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      CORY COMPONENTS, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      DETTMERS INDUSTRIES, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:


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<PAGE>


                                      ELSINORE AEROSPACE
                                      SERVICES, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      ELSINORE ENGINEERING, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      HOLLINGSEAD INTERNATIONAL, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      TRI-STAR ELECTRONICS
                                      INTERNATIONAL, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:


                                       6
<PAGE>

                                      PATS, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      PATRICK AIRCRAFT TANK SYSTEMS, INC.

                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      PATS SUPPORT, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:



                                      PATS AIRCRAFT AND ENGINEERING CORPORATION

                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:





                                      FLIGHT REFUELING, INC.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:


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                                      CWP ACQUISITION, INC., d/b/a
                                      Custom Woodwork & Plastics, Inc.





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:



                                      STATE STREET BANK AND TRUST COMPANY





                                      BY:
                                          ------------------------------------
                                          Name:
                                          Title:


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