§1048.315 How do I know when my engine family fails the production-line testing requirements?

This section describes the pass/fail criteria for the production-line testing requirements. We apply this criteria on an engine-family basis. See §1048.320 for the requirements that apply to individual 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 engine. If you do several tests on an engine, calculate the initial test results, then add them together and divide by the number of tests and round for the final test results on that engine.

(2) Final deteriorated test results. Apply the deterioration factor for the engine family to the final test results (see §1048.240(c)).

(b) Construct the following CumSum Equation for each engine family (for HC+NOX and for CO emissions): $$

Where:

Ci = The current CumSum statistic.

Ci-1 = The previous CumSum statistic. For the first test, CumSum statistic is 0 (i.e. C1 = 0).

Xi = The current emission test result for an individual engine.

STD = Emission standard.

(c) Use final deteriorated test results to calculate the variables in the equation in paragraph (b) of this section (see §1048.315(a)).

(d) After each new test, recalculate the CumSum statistic.

(e) If you test more than the required number of 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.

(h) If you amend the application for certification for an engine family (see §1048.225), do not change any previous calculations of sample size or CumSum statistics for the model year.