The FAA retrofit feasibility program is a success story. The cooperation of the aircraft industry in general, and the FAA's contractors in particular have made the success of the program possible. We can now state that all JT3D- and JT8D-powered aircraft can meet reduced noise levels, such as FAR 36 levels, by means of technologically feasible and economically reasonable nacelle retrofit solutions. These solutions will not aggravate the energy crisis by virtue of a negligible increase in fuel consumption for the nominal flight conditions.
A Notice of Proposed Rulemaking (NPRM) is about to be disseminated which could lead to the requirement that all JT3D/JT8D-powered aircraft be retrofitted by 1978 with quiet nacelles so that FAR 36 requirements can be satisfied.