Alterations, Modifications and Additions The Owner shall, or shall cause a Permitted Lessee to, make (or cause to be made) alterations and modifications in and additions to the Aircraft, Airframe and each Engine as may be required to be made from time to time to meet the applicable standards of the FAA or other Aviation Authority having jurisdiction over the operation of the Aircraft, to the extent made mandatory in respect of the Aircraft (a “Mandatory Modification”); except for (i) immaterial and non-recurring violations with respect to which corrective measures are being taken promptly by Owner or a Permitted Lessee and (ii) any law, rule, regulation or order the validity or application of which is being contested in good faith by the Owner or any Permitted Lessee in any reasonable manner which does not materially adversely affect the Indenture Trustee’s interest in the Aircraft, does not impair the Indenture Trustee’s security interest or International Interest in the Aircraft and does not involve any material risk of sale, forfeiture or loss of the Aircraft or the interest of the Indenture Trustee therein or any material risk of material civil penalty or any material risk of criminal liability being imposed on the Indenture Trustee or the holder of any Equipment Note. In addition, the Owner, at its own expense, may, or may permit a Permitted Lessee at its own cost and expense to, from time to time make or cause to be made such alterations and modifications in and additions to the Airframe or any Engine (each an “Optional Modification”) as the Owner or such Permitted Lessee may deem desirable in the proper conduct of its business including, without limitation, removal of Parts which the Owner deems are obsolete or no longer suitable or appropriate for use in the Aircraft, Airframe or such Engine; provided, however, that no such Optional Modification shall (i) materially diminish the fair market value, utility, or useful life of the Aircraft or any Engine below its fair market value, utility or useful life immediately prior to such Optional Modification (assuming the Aircraft or such Engine was in the condition required by this Trust Indenture immediately prior to such Optional Modification) or (ii) cause the Aircraft to cease to have the applicable standard certificate of airworthiness except that such certificate of airworthiness temporarily may be replaced by an experimental certificate during the process of implementing and testing such Optional Modification and securing related FAA re-certification of the Aircraft. For the avoidance of doubt, Owner may make alterations in the passenger configuration of the Aircraft and such alterations shall not constitute an Optional Modification. All Parts incorporated or installed in or attached to any Airframe or any Engine as the result of any alteration, modification or addition effected by the Owner shall be free and clear of any Liens except Permitted Liens and become subject to the Lien of this Trust Indenture; provided that the Owner or any Permitted Lessee may, at any time so long as the Airframe or any Engine is subject to the Lien of this Trust Indenture, remove any such Part (such Part being referred to herein as a “Removable Part”) from such Airframe or an Engine if (i) such Part is in addition to, and not in replacement of or in substitution for, any Part originally incorporated or installed in or attached to such Airframe or any Engine at the time of delivery thereof hereunder or any Part in replacement of, or in substitution for, any such original Part, (ii) such Part is not required to be incorporated or installed in or attached or added to such Airframe or any Engine pursuant to the terms of Section 4.02(d) or the first sentence of this Section 4.04(d) and (iii) such Part can be removed from such Airframe or any Engine without materially diminishing the fair market value, utility or remaining useful life which such Airframe or any Engine would have had at the time of removal had such removal not been effected by the Owner, assuming the Aircraft was otherwise maintained in the condition required by this Trust Indenture and such Removable Part had not been incorporated or installed in or attached to the Aircraft, Airframe or such Engine. Upon the removal by the Owner of any such Part as above provided in this Section 4.04(d), title thereto shall, without further act, be free and clear of all rights of the Indenture Trustee and such Part shall no longer be deemed a Part hereunder. Removable Parts may be leased from or financed by third parties other than the Indenture Trustee. Notwithstanding any other provision of this Indenture, Owner may, at any time, install or permit to be installed in the Aircraft Passenger Convenience Equipment owned by Owner or any Permitted Lessee or by third parties and leased or otherwise furnished to Owner in the ordinary course of business (including pursuant to a conditional sale contract, a licence or otherwise), and Owner may remove (and not replace) or permit to be removed (and not replaced) the same, and Indenture Trustee shall not acquire a Lien thereon by virtue of such installation or otherwise, and the rights of the owners therein shall not constitute a default under this Trust Indenture, it being acknowledged and agreed, however, that in no event shall the installation of any such Passenger Convenience Equipment impair or otherwise affect the rights and remedies of the Indenture Trustee hereunder and under applicable law.
