[Code of Federal Regulations]
[Title 40, Volume 31]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1051.243]

[Page 637-638]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1051_CONTROL OF EMISSIONS FROM RECREATIONAL ENGINES
AND VEHICLES--Table of Contents
 
                  Subpart C_Certifying Engine Families
 
Sec.  1051.243  How do I determine deterioration factors from exhaust
durability testing?

    Establish deterioration factors to determine whether your engines 
will meet emission standards for each pollutant throughout the useful 
life, as described in subpart B of this part and Sec.  1051.240. This 
section describes how to determine deterioration factors, either with 
pre-existing test data or with new emission measurements.
    (a) You may ask us to approve deterioration factors for an engine 
family based on emission measurements from similar vehicles or engines 
if you have already given us these data for certifying other vehicles in 
the same or earlier model years. Use good engineering judgment to decide 
whether the two vehicles or engines are similar. We will approve your 
request if you show us that the emission measurements from other 
vehicles or engines reasonably represent in-use deterioration for the 
engine family for which you have not yet determined deterioration 
factors.
    (b) If you are unable to determine deterioration factors for an 
engine family under paragraph (a) of this section, select vehicles, 
engines, subsystems, or components for testing. Determine deterioration 
factors based on service accumulation and related testing to represent 
the deterioration expected from in-use vehicles over the full useful 
life, as follows:
    (1) You must measure emissions from the emission-data vehicle at a 
low-hour test point and the end of the useful life. You may also test at 
evenly spaced intermediate points.
    (2) Operate the vehicle or engine over a representative duty cycle 
for a period at least as long as the useful life (in hours or 
kilometers). You may operate the vehicle or engine continuously.
    (3) You may perform maintenance on emission-data vehicles as 
described in Sec.  1051.125 and 40 CFR part 1065, subpart E.
    (4) If you measure emissions at only two points to calculate your 
deterioration factor, base your calculations on a linear relationship 
connecting these

[[Page 638]]

two data points for each pollutant. If you measure emissions at three or 
more points, use a linear least-squares fit of your test data for each 
pollutant to calculate your deterioration factor.
    (5) Use good engineering judgment for all aspects of the effort to 
establish deterioration factors under this paragraph (b).
    (6) You may to use other testing methods to determine deterioration 
factors, consistent with good engineering judgment.
    (c) Include the following information in your application for 
certification:
    (1) If you use test data from a different engine family, explain why 
this is appropriate and include all the emission measurements on which 
you base the deterioration factor.
    (2) If you do testing to determine deterioration factors, describe 
the form and extent of service accumulation, including a rationale for 
selecting the service-accumulation period and the method you use to 
accumulate hours.

[70 FR 40496, July 13, 2005]