EXHIBIT 3.21

                               The Companies Act, 1943

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                              COMPANY LIMITED BY SHARES

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                              MEMORANDUM OF ASSOCIATION

                                          of

                                 PLESSEY DIAC LIMITED

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l.     The Name of the Company is "DIAC (AIRCRAFT) LIMITED".

2.     The Registered Office of the Company will be situated in England.

3.     The Objects for which the Company is established are:

       (A)    To carry on all or any of the businesses of Designers,
              Manufacturers, Fitters, and Repairers of and Dealers in
              Components, Parts, Engines, Machinery, and other accessors,
              supplies, and apparatus of every description used or required in
              connection with Prototype and experimental Aircraft, Aircraft of
              all types, Aeronautical Experts in all branches of the Aircraft
              Industry, Aeronautical, Electrical, Motor, Consulting, Mechanical
              and General Engineers, Engineering Contractors and Designers,
              Electricians, Tool Makers, Metal Workers, Machinists, Wood
              Workers, Wireworkers, Galvanisers, and Painters, Proprietors of
              Aerodromes, Hangars, Landing Places, Piers, Jetties, Repairing and
              Petrol Filling Stations, Garages, Boat Houses, Factories and
              Works, and to promote, assist, and encourage by investigation,
              experiment, and all other means whatsoever, aircraft construction
              in all its branches.

       (B)    To manufacture, buy, sell, let on hire, repair, alter, adapt, and
              deal in all kinds of engines, plant, machinery tools, implements,
              apparatus, accessories, storage articles, substances, materials,
              produce and things capable of being used in connection with the
              foregoing businesses or any of them or solely to be required by
              customers of or persons having dealings with the Company.

       (C)    To carry on any other business (whether manufacturing or
              otherwise) which may seem to the Company capable of being
              conveniently carried on in connection with

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              the above objects, or calculated directly or indirectly to
              enhance the value of or render more profitable any of the
              Company's property.

       (D)    To purchase or by any other means acquire any freehold, leasehold,
              or other property for any estate or interest whatever, and any
              rights, privileges or easements over or in respect of any
              property, and any buildings, offices, factories, mills, works,
              wharves, roads, railways, tramways, machinery, engines, rolling
              stock, vehicles, plant, live and dead stock, barges, vessels, or
              things, and any real or personal property or rights whatsoever
              which may be necessary for, or may be conveniently used with, or
              may enhance the value of any other property of the Company.

       (E)    To build, construct, maintain, alter, enlarge, pull down, and
              remove or replace any buildings, offices, factories, mills, works,
              wharves, roads, railways, tramways, machinery, engines, walls,
              fences, banks, dams, sluices, or watercourses and to clear sites
              for the same or to join with any person, firm, or company in doing
              any of the things aforesaid, and to work, manage, and control the
              same or join with others in so doing.

       (F)    To apply for, register, purchase, or by other means acquire and
              protect, prolong, and renew, whether in the United Kingdom, or
              elsewhere, any patents, patent rights, brevets d'invention,
              licences, trade marks, designs, protections, and concessions which
              may appear likely to be advantageous or useful to the Company, and
              to use and turn to account and to manufacture under or grant
              licences or privileges in respect of the same, and to expend money
              in experimenting upon and testing and in improving or seeking to
              improve any patents, inventions, or rights which the Company may
              acquire or propose to acquire.

       (G)    To acquire and undertake the whole or any part of the business,
              goodwill, and assets of any person, firm or company carrying on or
              proposing to carry on any of the businesses which this Company is
              authorised to carry on, and as part of the consideration for such
              acquisition to undertake all or any of the liabilities of such
              person, firm or company, or to acquire an interest in, amalgamate
              with, or enter into partnership or into any arrangement for
              sharing profits, or for cooperation, or for limiting competition
              or for mutual assistance with any such person, firm, or company,
              and to give or accept, by way of consideration for any of the acts
              or things aforesaid or property acquired, any Shares, Debentures,
              Debenture Stock, or securities that may be agreed upon, and to
              hold and retain, or sell mortgage, and deal with any shares,
              debentures, debenture stock, or securities so received.

       (H)    To improve, manage, cultivate, develop, exchange, let on lease or
              otherwise, mortgage, charge, sell, dispose of, turn to account,
              grant rights and privileges in

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              respect of, or otherwise deal with all or any part of the property
              and rights of the Company.

       (I)    To invest and deal with the moneys of the Company not immediately
              required in such shares or upon such securities and in such manner
              as may from time to time be determined.

       (J)    To lend and advance money or give credit to such persons, firms,
              or companies and on such terms as may seem expedient, and in
              particular to customers of and others having dealings with the
              Company, and to give guarantees or become security for any such
              persons, firms, or companies.

       (K)    To borrow or raise money in such manner as the Company shall think
              fit, and in particular by the issue of Debentures or Debenture
              Stock (perpetual or otherwise), and to secure the repayment of any
              money borrowed, raised, or owing, by mortgage, charge, or lien
              upon the whole or any part of the Company's property or assets
              (whether present or future), including its uncalled Capital and
              also by a similar mortgage, charge or lien to secure and guarantee
              the performance by the Company of any obligation or liability it
              may undertake.

       (L)    To draw, make, accept, endorse, discount, execute, and issue
              promissory notes, bills of exchange, bills of lading, warrants,
              debentures, and other negotiable or transferable instruments.

       (M)    To apply for, promote, and obtain any Act of Parliament,
              Provisional Order, or Licence of the Board of Trade or other
              authority for enabling the Company to carry any of its objects
              into effect, or for effecting any modification of the Company's
              constitution, or for any other purpose which may seem expedient,
              and to oppose any proceedings or applications which may seem
              calculated directly or indirectly to prejudice the Company's
              interests.

       (N)    To enter into any arrangements with any Governments or authorities
              supreme, municipal, local, or otherwise, or any companies, firms,
              or persons that may seem conducive to the attainment of the
              Company's objects or any of them, and to obtain from any such
              Government, authority, company, firm, or person any charters,
              contracts, decrees, rights, privileges, and concessions which the
              Company may think desirable, and to carry out, exercise, and
              comply with any such charters, contracts, decrees, rights,
              privileges, and concessions.

       (O)    To subscribe for, take, purchase, or otherwise acquire and hold
              shares or other interests in or securities of any other company
              having objects altogether or in part similar to those of this
              Company or carrying on any business capable of being carried on so
              as directly or indirectly to benefit this Company.

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       (P)    To act as agents or brokers and as trustees for any person, firm,
              or company, and to undertake and perform sub-contracts, and also
              to act in any of the businesses of the Company through or by means
              of agents, brokers, sub-contractors, or others.

       (Q)    To remunerate any person, firm, or company rendering services to
              this Company, either by cash payment or by the allotment to him or
              them of Shares or securities of the Company credited as paid up in
              full or in part or otherwise as may be thought expedient.

       (R)    To pay all or any expenses incurred in connection with the
              promotion, formation, and incorporation of the Company, or to
              contract with any person, firm, or company to pay the same, and to
              pay commissions to brokers and others for underwriting, placing,
              selling, or guaranteeing the subscription of any Shares,
              Debentures, Debenture Stock, or securities of this Company.

       (S)    To support and subscribe to any charitable or public object, and
              any institution, society, or club which may be for the benefit of
              the Company or its employees, or may be connected with any town or
              place where the Company carries on business, to give or award
              pensions, annuities, gratuities, and superannuation or other
              allowances or benefits or charitable aid to any persons who are or
              have been Directors of, or who are or have been employed by, or
              who are serving or have served the Company, and to the wives,
              widows, children, and other relatives and dependents of such
              persons; to make payments towards insurance; and to set up,
              establish, support, and maintain superannuation and other funds or
              schemes (whether contributory or non-contributory) for the benefit
              of any of such persons and of their wives, widows, children, and
              other relatives and dependents.

       (T)    To promote any other company for the purpose of acquiring the
              whole or any part of the business or property and undertaking any
              of the liabilities of this Company, or of undertaking any business
              or operations which may appear likely to assist or benefit this
              Company or to enhance the value of any property or business of
              this Company, and to place or guarantee the placing of,
              underwrite, subscribe to, or otherwise acquire all or any part of
              the shares or securities of any such company as aforesaid.

       (U)    To sell or otherwise dispose of the whole or any part of the
              business or property of the Company, either together or in
              portions, for such consideration as the Company may think fit, and
              in particular for shares, debentures, or securities of any company
              purchasing the same.

       (V)    To distribute among the Members of the Company in kind any
              property of the Company, and in particular any shares, debentures,
              or securities of other

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              companies belonging to this Company or of which this Company may
              have the power of disposing.

       (W)    To procure the Company to be registered or recognised in any
              Dominion or Dependency and in any Foreign Country or place.

       (X)    To do all such other things as may be deemed incidental or
              conducive to the attainment of the above objects or any of them.

It is hereby expressly declared that each Sub-Clause of this Clause shall be
construed independently of the other Sub-Clauses hereof, and that none of the
objects mentioned in any Sub-Clause shall be deemed to be merely subsidiary to
the objects mentioned in any other Sub-Clause.

4.     The Liability of the Members is Limited.

5.     The Share Capital of the Company is One Thousand Pounds, divided into
       One Thousand Shares of One Pound each.

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WE, the several persons whose Names, Addresses, and Descriptions are subscribed
are desirous of being formed into a Company in pursuance of this Memorandum of
Association; and we respectively agree to take the number of Shares in the
Capital of the Company set opposite our respective names.



                                                     
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NAMES, ADDRESSES AND DESCRIPTIONS OF SUBSCRIBERS        No. of Shares taken
                                                        by each Subscriber
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WILFRED THOMPSON NEWTON                                 One
105 Kingswood Road
Bromley, Kent,

Engineer
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KURT WHITBY                                             One
30 Fitzjames Avenue
Croydon, Surrey

Timber Merchant
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                                   TOTAL SHARES TAKEN   Two
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       Dated the 1st day of July, 1955.


       WITNESS to the above Signatures:

              DEREK D. WILLIAMSON

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