EXHIBIT 4.11

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                                 TRANSDIGM INC.,

                           THE GUARANTORS named herein

                                       and

                 STATE STREET BANK AND TRUST COMPANY, as Trustee

                                 ---------------

                             SUPPLEMENTAL INDENTURE


                            Dated as of June 26, 2001

                                       To
                     Indenture Dated as of December 3, 1998
                                  By and Among
                                 TRANSDIGM INC.,
                        the Guarantors named therein and
                                   the Trustee
                                 ---------------

                  Pursuant to which were issued $200,000,000 of
                   10-3/8% Senior Subordinated Notes due 2008
                                of TransDigm Inc.

                                 ---------------

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                             SUPPLEMENTAL INDENTURE

      SUPPLEMENTAL INDENTURE (this "SUPPLEMENTAL INDENTURE"), dated as of June
26, 2001 among Champion Aerospace Inc., a Delaware corporation, Christie
Electric Corp., a California corporation (collectively, the "GUARANTEEING
SUBSIDIARIES" and, each, a "GUARANTEEING SUBSIDIARY"), each a subsidiary of
TransDigm Inc., a Delaware corporation (the "COMPANY"), the Company, TransDigm
Holding Company, a Delaware corporation ("HOLDINGS"), Adams Rite Aerospace,
Inc., a California corporation ("ADAMS RITE"), ZMP, Inc., a California
corporation ("ZMP"), and Marathon Power Technologies Company, a Delaware
corporation ("MARATHON" and, together with Adams Rite, ZMP, Holdings and the
Guaranteeing Subsidiaries, the "GUARANTORS") 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 Company, Holdings and Marathon have heretofore executed and
delivered to the Trustee an indenture (the "Indenture"), dated as of December 3,
1998 providing for the issuance of an aggregate principal amount of up to $200.0
million of 10 3/8% Senior Subordinated Notes due 2008 (the "NOTES") and the
guarantees thereof by Holdings and Marathon;

      WHEREAS, the Indenture provides that under certain circumstances newly
acquired Subsidiaries of the Company shall execute and deliver to the Trustee a
supplemental indenture pursuant to which such Subsidiaries shall unconditionally
guarantee all of the Company's Obligations under the Notes and the Indenture on
the terms and conditions set forth therein (the "GUARANTEE");

      WHEREAS, the Company, Holdings, Marathon, Adams Rite and ZMP have
heretofore executed and delivered to the Trustee a supplemental indenture, dated
as of April 23, 1999 providing for Adams Rite and ZMP to become Guarantors under
the Indenture; and

      WHEREAS, pursuant to Section 9.01 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
Guaranteeing Subsidiary 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. Each Guaranteeing Subsidiary 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 the Company 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, if lawful, and all other
                  obligations of the Company 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 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 the Company, 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 Company, any right to require a proceeding first against
      the Company, protest, notice and all demands whatsoever.

            (d) This Guarantee shall not be discharged except by complete
      performance of the obligations contained in the Notes and the Indenture or
      pursuant to Section 6 hereof.

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

            (f) Each Guaranteeing Subsidiary 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.


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            (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 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
      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, the obligations of each Guaranteeing Subsidiary shall be
      limited to the maximum amount as will result in the obligations of such
      Guarantor under its Guarantee not constituting a fraudulent transfer or
      conveyance.

      3. SUBORDINATION. The obligations of each Guaranteeing Subsidiary under
its guarantee pursuant to this Supplemental Indenture shall be junior and
subordinated to the Senior Debt of each such Guaranteeing Subsidiary on the same
basis as the Notes are junior and subordinated to the Senior Debt of the
Company. For the purposes of the foregoing sentence, the Trustee and the Holders
shall have the right to receive and/or retain payments by each Guaranteeing
Subsidiary only at such time as they may receive and/or retain payments in
respect of the notes pursuant to the indenture, including Article 10 thereof.

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

      5. GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN TERMS. Each
Guaranteeing Subsidiary will be subject to Section 11.05 of the Indenture.

      6. 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 to the capital stock of any Guarantor, then
      such Guarantor (in the event of a sale or other disposition, by way of
      merger, consolidation or otherwise, of all of the capital stock of such
      Guarantor) or the corporation


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      acquiring the property (in the event of a sale or other disposition of all
      or substantially all of the assets of such Guarantor) will be released and
      relieved of any obligations under its 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 Company 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 Company in accordance with
      the 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 Guarantee.

            (b) Any Guarantor not released from its obligations under its
      Guarantee shall remain liable for the full amount of principal of and
      interest on the and for the other obligations of any guarantor under the
      indenture as provided in Article 10 of the indenture.

      7. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder or agent of either Guaranteeing
Subsidiary, as such, shall have any liability for any obligations of the Company
or any Guaranteeing Subsidiary under the Notes, any 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 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.

      8. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK SHALL
GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE 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.

      9. 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.

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

      11. 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 the Guaranteeing Subsidiaries and the Company.





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      IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

                                     TRANSDIGM, INC.

Dated: June 26, 2001

                                     By:      /s/ GREGORY RUFUS
                                        -------------------------------------
                                        Name: Gregory Rufus
                                        Title: Vice President, Chief Financial
                                                 Officer and Assistant Secretary


                                     TRANSDIGM HOLDING COMPANY


                                     By:      /s/ GREGORY RUFUS
                                        ----------------------------------------
                                        Name: Gregory Rufus
                                        Title: Vice President, Chief Financial
                                                 Officer and Assistant Secretary


                                     MARATHON POWER TECHNOLOGIES COMPANY



                                     By:      /s/ GREGORY RUFUS
                                        ----------------------------------------
                                        Name:  Gregory Rufus
                                        Title: Chief Financial Officer and
                                                 Assistant Secretary



                                     ADAMS RITE AEROSPACE, INC.


                                     By:      /s/ GREGORY RUFUS
                                        ----------------------------------------
                                        Name: Gregory Rufus
                                        Title: Treasurer, Chief Financial
                                                 Officer and Assistant Secretary



                                      ZMP, INC.


                                      By:      /s/ GREGORY RUFUS
                                         ---------------------------------------
                                         Name: Gregory Rufus
                                         Address
                                         Title: Treasurer, Chief Financial
                                                 Officer and Assistant Secretary


                                      CHAMPION AEROSPACE INC.


                                      By:      /s/ GREGORY RUFUS
                                         ---------------------------------------
                                         Name: Gregory Rufus
                                         Title: Vice President and Secretary



                                      CHRISTIE ELECTRIC CORP.


                                      By:      /s/ GREGORY RUFUS
                                         ---------------------------------------
                                         Name:  Gregory Rufus
                                         Title:



                                      STATE STREET BANK AND TRUST
                                      COMPANY, as Trustee


                                      By:      /s/ MICHAEL M. HOPKINS
                                         ---------------------------------------
                                         Name:  Michael M. Hopkins
                                         Title:  Vice President