This section describes the pass-fail criteria for the production-line testing requirements. We apply these criteria on an engine family basis. See§ 1051.320 for the requirements that apply to individual vehicles or engines that fail a production-line test.
(a) Calculate your test results. Round them to the number of decimal places in the emission standard expressed to one more decimal place.
(1) Initial and final test results. Calculate and round the test results for each vehicle or engine. If you do several tests on a vehicle or engine, calculate the initial results for each test, then add all the test results together and divide by the number of tests. Round this final calculated value for the final test results on that vehicle or engine.
(2) Final deteriorated test results. Apply the deterioration factor for the engine family to the final test results (see § 1051.240(c)).
(3) Round deteriorated test results. Round the results to the number of decimal places in the emission standard expressed to one more decimal place.
(b) Construct the following CumSum Equation for each engine family for HC, NOX (HC + NOX), and CO emissions:
Ci = Max [0 or Ci−1 + Xi−(STD + 0.25 × σ)]
Where:
Ci = The current CumSum statistic.
Ci−1 = The previous CumSum statistic. For the first test, the CumSum statistic is 0 (i.e., C1 = 0).
Xi = The current emission test result for an individual vehicle or engine.
STD = Emission standard (or family emission limit, if applicable).
(c) Use final deteriorated test results to calculate the variables in the equation in paragraph (b) of this section (see § 1051.315(a)).
(d) After each new test, recalculate the CumSum statistic.
(e) If you test more than the required number of vehicles or engines, include the results from these additional tests in the CumSum Equation.
(f) After each test, compare the current CumSum statistic, Ci, to the recalculated Action Limit, H, defined as H = 5.0 × σ.
(g) If the CumSum statistic exceeds the Action Limit in two consecutive tests, the engine family fails the production-line testing requirements of this subpart. Tell us within ten working days if this happens. You may request to amend the application for certification to raise the FEL of the engine family as described in § 1051.225(f).
(h) If you amend the application for certification for an engine family under § 1051.225, do not change any previous calculations of sample size or CumSum statistics for the model year.
[67 FR 68347, Nov. 8, 2002, as amended at 70 FR 40499, July 13, 2005; 73 FR 59252, Oct. 8, 2008]