40 CFR 86.432-78 - Deterioration factor.
(a) Deterioration factors shall be developed for each test vehicle from the emission test results. A separate factor shall be developed for each pollutant. The applicable data to be used in calculating these factors are:
(3) The results from tests conducted before and after unscheduled maintenance, if approval of the maintenance by the Administrator was conditioned on the data being used in the deterioration factor calculation.
(b) Emission results which are less than 0.10 g/km shall be considered to be 0.10 g/km for purposes of this section.
(c) Test results for each pollutant shall be plotted as a function of the service accumulated at the start of the emission test, rounded to the nearest kilometre. These results shall be correlated to a straight line, fit by the method of least squares.
(d) An exhaust emission deterioration factor will be calculated by dividing the predicted emissions at the useful life distance by the predicted emissions at the total test distance. Predicted emissions are obtained from the correlation developed in paragraph (c) of this section.
(e) Deterioration factors computed to be less than 1.000 shall be 1.000.
(2) The outlier procedure will be specified by the Administrator.
(3) For any pollutant, durability-data test points that are identified as outliers shall not be included in the determination of deterioration factors if the manufacturer has elected this option.
(6) Where the manufacturer chooses to apply the outlier procedure to a data set containing data which were averaged under § 86.427-78(e), the outlier procedure shall be completed before averaging the data.