; and (B) decrease backlogs and lead times for the production of parts for such aircraft. (2) To advance the qualification, certification, and integration of additive manufacturing into the Air Force supply chain. (3) To otherwise identify and reduce supply chain risk for the Air Force. (4) To define workforce development requirements and training for personnel who implement and support additive manufacturing for the Air Force at the warfighter, end-item designer and equipment operator, and acquisition officer levels. (b) Funding Of the amounts authorized to be appropriated for fiscal year 2019 by section 201 for research, development, test, and evaluation for the Air Force and available for Tech Transition Program (Program Element (0604858F)), up to $42,800,000 may be available as described in subsection (a). 238. Review of guidance on blast exposure during training (a) Initial review Not later than 180 days after the date of the enactment of this Act, the Secretary of Defense shall review the firing limits for heavy weapons during training exercises. (b) Elements The review required by subsection (a) shall take into account current data and evidence on the cognitive effects of blast exposure and shall include consideration of the following: (1) The impact of exposure over multiple successive days of training. (2) The impact of multiple types of heavy weapons being fired in close succession. (3) The feasibility of cumulative annual or lifetime exposure limits. (4) The minimum safe distance for observers and instructors. (c) Updated training guidance Not later than 180 days after the date of the completion of the review under subsection (a), each Secretary of a military department shall update any relevant training guidance to account for the conclusions of the review. (d) Updated review (1) In general Not less frequently than once every two years after the initial review conducted under subsection (a), the Secretary of Defense shall conduct an updated review under such subsection, including consideration of the