Interviews conducted with avionic design engineers, both at prime and subcontractor facilities, indicated that here is a real problem of determining what features of new esign might be a cause of corrosion problems affecting avionic equipment reliability and maintainability in the fleet. To date, designing avionic equipment to the present available Military Specifications and the testing of equipment based on laboratory conditions vice the "real world" environment have not been adequate to ensure the newly designed equipment will be capable of existing in the environment in which it must function. Translating specific fleet failure modes into preventive Military Specification requirements is a desirable approach, but such specifications can never cover all possible problems. Engineering
judgement will always be required to apply general principles to the specifics of new designs. The problem, of course, is to acquire the information upon which a sound engineering judgement may be based. The following is a summary of the related points from the interviews conducted with avionic design engineers located at subcontractors:
a. Most new avionic equipment is designed by subcontractors working to the requirements imposed by the new weapons system prime (normally airframe) contractor. The prime contractor does not tell the subcontractor how to design the equipment. This relationship assumes the procurement specifications are totally adequate or that the subcontractor has the experience and understanding of the naval environment to make the proper design decisions wherever the specifications are not definitive.
b. It is a rare case that the original design engineers are made aware of how their design ultimately worked in the fleet environment. It may be five years or more after completion of developmental design before significant fleet corrosion experience will begin to accrue. In the meantime, these engineers are working on other equipment or for other employers. They receive no personal knowledge of environmentally exposed design weaknesses as a basis for not repeating such designs.
c. The fleet identified problems are corrected primarily by the prime contractor or the CFA (Cognizant Field Activity). Seldom does feedback on a fleet instigated failure investigation reach the subcontractor, via the prime, so that the subcontractor's corporate design practices guide can be updated.
Placing an indictment alone on the inadequacy of the Military Specifications and laboratory testing requirements will not lead to the solution for precluding corrosion degradation of newly designed equipment. Basically, design improvement of almost any kind of complex item involves an iterative process wherein design weaknesses are identified and corrective
(preventive) features are incorporated in subsequent models and retrofitted, as appropriate. This same iterative process is required to identify and correct weaknesses in the Military Specifications and laboratory testing requirements, but it must be recognized that the complexity of the naval environment is such that the interacting factors cannot all be detailed in specifications nor duplicated in accelerated laboratory testing.
An approach to improving reliability and maintainability of new design and in-service equipment, including Military Specifications and laboratory testing requirements, is a more definitive use of fleet level feedback. This data source appears to be a missing link in the present design information system supporting the engineer presently attempting to produce equipment with little or no data on reliability and maintainability problems associated with corrosion. The following are related to the fleet description of the general environment, and are considered prime sources of information and feedback on fleet corrosion problems that must be utilized by avionic equipment design engineers if new designs are to reflect past reliability and maintainability solutions to C/F/M induced failures:
a. Design/test specification interpretations
b. Quantitative design feedback sources
c. Qualitative design feedback sources