Low-density polysulfide-based sealants are at the leading edge of engineering technology for sealing processes applicable to military and commercial aircraft. This paper focuses on a major aircraft manufacturer's quality assurance (QA) system dedicated to testing and evaluating sealants for placement on applicable Qualified Products Lists (QPLs); This QA system enabled this aircraft manufacturer to qualify two Class C designations -- Classes C-2 and C-48 -- of low-density sealants. The generic procedure for qualification of low-density sealants, especially Class C materials, is explained from the aircraft manufacturer's point of view. The Engineering decisionmaking process for selecting and documenting property test requirements for qualification of aircraft sealants is discussed. Despite the time-intensive nature of the generic sealant qualification process, the author concludes that sealant qualification is a worthwhile and necessary effort, which demands comprehensive testing and frequent technical coordination within airframe manufacturer's Engineering and Materiel organizations and with suppliers of aircraft sealing products.