EVALUATION OF LOW VOC ADHESIVE BONDING PRIMERS FOR MILITARY AND COMMERCIAL HELICOPTER APPLICATIONS

Because of new environmental rules going into effect in the near future, new, low VOC bonding primers must be qualified for helicopter structural bonding applications. McDonnell Douglas Helicopter Systems (MDHS) developed four criteria for evaluating new materials. The criteria were developed to initially use lower cost test methods to generate data. These criteria were: environmental considerations, manufacturing and processing, corrosion resistance and bonding considerations. Screening program manufacturing shop trials eliminated two candidates from consideration. One candidate was eliminated for not meeting the current VOC limit. Three nonchromated primers were discontinued because of poor corrosion resistance compared to the current material, Dexter Hysol EA9210H. Four more candidates were eliminated during mechanical property testing. Currently only one candidate, Cytec 6747-1, merits possible further consideration. Qualification will begin when a candidate successfully completes the screening program. The selected primer must be ready for production by January 1, 1996.