But do you need a DA when you put the aircraft on a US experimental registration? Asking for a friend....
I think you already know the answer to that one
folk here might be more interested in the verbiage from the PWS.
3.2.1.1 FAA Standard Airworthiness Certificates
For aircraft with FAA Standard Airworthiness Certificates, the Contractor shall maintain the aircraft IAW 14 CFR § 43. The Contractor shall secure FAA approval for each change to the configuration that is not defined in the aircraft’s Airworthiness Certificate before the change is used in support of this contract. For each such modification, the Contractor shall secure and provide the valid FAA-approved data within 90 days of task order award and as generated or requested (Exhibit A, CDRL A001). For Type Certificated aircraft, if this data references FAA regulations as the standard, the Contractor shall provide approved data as defined in the FAA Order 8300.16A for any major alteration or major repair. Major alterations to aircraft with Standard Airworthiness Certificates shall have been certified as airworthy and properly documented using FAA Form 337 signed in blocks six (6) (Conformity) and seven (7) (Return to Service) by persons authorized under 14 CFR § 43, and citing FAA Approval Data. The FAA may only certify modifications relating to powered systems for captive carriage if the operation of that system in not considered commercial purposes, per 49 United States Code (USC) § 40125.
3.2.1.2 FAA Special Airworthiness Certificates
For aircraft with FAA Special Airworthiness Certificates, the Contractor shall provide the Program Letter (PL) submitted to the FAA for application of the airworthiness certificate used in support of this contract or latest PL associated with the current airworthiness certificate. Under this certificate, the aircraft must be maintained in accordance with the operating limitations issued as part of that certificate. For each subsequent aircraft modification deviating from the FAA issued certificate, the contractor shall secure and provide an updated FAA airworthiness certification, and associated operating limitations (Exhibit A, CDRL A001), before the modification is used in support of this contract. Where the modification is a major change (as defined by 14 CFR § 43), the Contractor shall provide the PL and secure the FAA's determination regarding the need for new or amended certificates. All major alterations incorporated before contract award and during contract execution shall have sufficient data to determine that the equipment or provisions for the equipment meet the applicable civil, Original Equipment Manufacturer (OEM), (MIL-STD), or some other recognized engineering substantiation data, for the type of aircraft concerned. Unless directed otherwise by the Government, the Contractor shall remove any major alteration incorporated before contract award that was not certified as airworthy by an appropriately rated FAA certified mechanic, aircraft manufacturer or repair station.
3.2.1.3 For aircraft with FAA Special Airworthiness Certificates, in addition to the FAA approved Aircraft Inspection/Maintenance Program, the contractor shall prepare Instructions for Continued Airworthiness (ICA) consistent with 14 CFR § 25 Subpart H – Electrical Wiring Interconnection Systems (EWIS) and provide IAW Exhibit A, CDRL A001. This includes any modifications done to the aircraft from the baseline that involves electrical wiring not currently covered in the AIP or the existing maintenance plan.
3.2.2 NAVAIR Airworthiness Supporting Data
3.2.2.1 The Contractor shall provide a single point-of-contact to manage the airworthiness certifications and to coordinate Contractor and Government certification efforts during the Stand-up phase of each aircraft type or during any significant aircraft modification requiring a new or updated USN IFC.
3.2.2.2 All aircraft under this contract require a USN issued IFC (NAVAIRINST 13034.1F). All aircraft must be able to perform IAW Table 3.1 and a complete substantiation data set shall be submitted IAW Exhibit A, CDRL A001. If additional substantiation data is required during the Government’s review the contractor shall promptly deliver the data. In the absence of FAA, OEM, or Military approved data, the contractor shall follow the recommended repair and alteration processes and procedures described in: AC 43-210A, Standardized Procedures for Obtaining Approval of Data Used in the Performance of Major Repairs and Major Alterations, the Major Repair and Alteration Data Approval Job Aid, or MIL-HDBK-516, the Department of Defense Handbook Airworthiness Certification Criteria. For initial airworthiness assessment in support of a USN IFC, all airworthiness data shall be provided to the Government after contract award in accordance with Exhibit A, CDRL A001. For subsequent aircraft modifications substantiation data shall be provided at least thirty (30) days prior to the required mission.