(a) This section applies only to Phase 1 engines. In-use testing provisions for Phase 2 engines are found in subpart M of this part. At the time of certification the engine manufacturer may propose which engine families should be included in an in-use test program. EPA will approve a manufacturer's test program if the selected engine families represent an adequate consideration of the elements listed in paragraphs (b) and (c) of this section.

(b) Number of engines to be tested. The number of engines to be tested by a manufacturer is determined by the following method:

(1) For an engine manufacturer with total projected annual production of more than 75,000 engines destined for the United States market for that model year, the minimum number of engines to be tested may be the lowest of the numbers determined in paragraph (b)(1)(i), (ii) or (iii) of this section:

(i) Divide the manufacturer's total projected annual production of small SI engines destined for the United States market for that model year by 50,000, and round to the nearest whole number;

(ii) Test five engines each from 25 percent of all engine families certified in that model year; and

(iii) Test three engines each from 50 percent of all engine families certified in that model year.

(2) An engine manufacturer with total projected annual production of 75,000 engines or less destined for the United States market for that model year may test a minimum of two engines.

(c) Criteria for selecting test engines. An engine manufacturer may select test engines from engine families utilizing the following criteria and in the order specified:

(1) Engine families using emission control technology which most likely will be used on Phase 2 engines;

(2) Engine families using aftertreatment;

(3) Engine families certified to different emission standards;

(4) Different engine designs (such as sidevalve head versus overhead valve engines);

(5) Engine families using emission control technology specifically installed to achieve compliance with emission standards of this part;

(6) The engine family with the highest projected annual sales; and

(7) Engine families which meet the above criteria, but have not been included in prior model year in-use testing programs as required by these provisions.

(d) Collection of in-use engines. An engine manufacturer may procure in-use engines which have been operated for between half and three-quarters of the engine's advertised (or projected) useful life. All testing may be completed within three years from the date the certificate is first issued for an engine family undergoing in-use testing.

(1) Test engines may be procured from sources not associated with the engine manufacturer or vehicle manufacturer, except that with prior approval of the Administrator, an engine manufacturer with annual sales of less than 50,000 engines may obtain in-use engines associated with itself or its vehicle manufacturer.

(2) A test engine should have a maintenance history representative of actual in-use conditions.

(i) A manufacturer may question the end user regarding the accumulated usage, maintenance, operating conditions, and storage of the test engines.

(ii) Documents used in the procurement process may be maintained as required in §90.121.

(3) Maintenance and testing of test engines.

(i) The manufacturer may perform minimal set-to-spec maintenance on a test engine. Maintenance may include only that which is listed in the owner's instructions for engines with the amount of service and age of the acquired test engine.

(ii) Documentation of all maintenance and adjustments may be maintained and retained as required by §90.121.

(4) One valid emission test may be conducted for each in-use engine.

(5) If a selected in-use engine fails to comply with any applicable certification emission standard, the manufacturer may determine the reason for noncompliance. The manufacturer may report all determinations for noncompliance in its annual in-use test result report as described below.

(e) In-use test program reporting. The manufacturer may submit to the Administrator by January 30 of each calendar year all emission testing results generated from in-use testing. The following information may be reported for each test engine:

(1) Engine family;

(2) Model;

(3) Engine serial number;

(4) Date of manufacture;

(5) Estimated hours of use;

(6) Results of all emission testing;

(7) Summary of all maintenance and/or adjustments performed;

(8) Summary of all modifications and/or repairs; and

(9) Determinations of compliance and/or noncompliance.

(f) The Administrator may approve and/or suggest modifications to a manufacturer's in-use testing program.

[60 FR 34598, July 3, 1995, as amended at 64 FR 15239, Mar. 30, 1999]