Performance Specification Guide SD-15
EXAMPLE 10 - CONSTRUCTION REQUIREMENTS
Performance specifications should not contain requirements on how the end item is to be constructed or assembled. Detailed specifications for end items often do contain lengthy and specific instruction on how an item is to be made, which does not allow for using alternative approaches that may be more cost effective or provide superior performance. Including detailed construction requirements can become a major problem if the specification is not kept current and the requirements do not reflect the latest industry practices. In the following example from detail specification MIL-L-81542A, Life Raft, Inflatable, One-Man, Type LR-1, the specific instructions on how to cement and stitch seams were removed and replaced with performance outcomes throughout the performance specification MIL-PRF-81542B, Life
Raft, Inflatable, Single-Place. Some of the paragraphs from MIL-PRF-81542B related to seam performance are given below. Both the detail military and revised performance specification can be viewed in their entirety on the ASSIST database at https://assist.daps.dla/quicksearch/.
MIL-L-81542A, Life Raft, Inflatable, One- Man, Type LR-1 |
MIL-PRF-81542B, Life Raft, Inflatable, Single-Place |
3.4.3 Cementing of the seams, seam tapes, patches, and attachments. The construction of the seams and the cementing of the seam tapes, patches, and attachments shall use the technique and precautions in 3.4.2 so that, prior to the inspection of the assembled life raft, the adhesive shall have developed its optimum bonding properties and the adherence of all such seams, seam tapes, patches, and attachments shall comply with the requirements of this specification. All the seams, seam tapes, patches, and attachments shall be secured by the adhesive specified in the applicable drawings. The tube radial joining seams shall be covered, on the inner and outer sides, with the seam tape as specified in 67A318H2. The tube longitudinal seam shall be covered on the inner side, with the seam tape and, on the outer side, by the attachment of the floor as specified in 67A318H2. All the seam tapes shall be applied to the seams without tension, and wrinkles, and shall be applied in accordance with the applicable drawing requirements. The floor, patches, and attachments shall also be cemented to the life raft without tension or wrinkles. The internal diametral opening in the |
3.19 Function/operation. The life raft shall inflate at the required pull force to its design shape in not greater than 60 seconds when tested as specified in 4.11. During the inflation, the life raft shall be observed for impediment or blockage of the flow of gas, loss of gas to the ambient air, or restriction by any component or accessory. There shall be no evidence of structural or material failure in any respect. All the sealed areas, seams, seam tapes, and attachments shall remain intact and shall show no indication of separation. The floor shall not be distorted and there shall not be a difference in the rise between the sides of the raft. The erected canopy shall withstand 35- knot winds and 52-knot gusts in open water. The life raft shall demonstrate seaworthiness and stability in an open sea condition of 17 to 27 knot winds and waves of 6 to 10 feet. The raft shall be easily boarded by a subject wearing standard aviation life support equipment including a flight suit, survival vest, inflated life preserver, and flight boots. See table I for anthropometric data. 3.20.1.1 Low temperature. The life raft shall inflate into a boardable shape within 5 minutes |
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