[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: 40CFR1051.240]

[Page 636-637]
 
                   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.  1051.240  How do I demonstrate that my engine family complies with 
exhaust emission standards?

    (a) For purposes of certification, your engine family is considered 
in compliance with the applicable numerical exhaust emission standards 
in subpart B of this part if all emission-data vehicles representing 
that family have test results showing deteriorated emission levels at or 
below these standards. (Note: if you participate in the ABT program in 
subpart H of this part, your FELs are considered to be the applicable 
emission standards with which you must comply.)
    (b) Your engine family is deemed not to comply if any emission-data 
vehicle representing that family has test results showing a deteriorated 
emission level above an applicable FEL or emission standard from subpart 
B of this part for any pollutant.
    (c) To compare emission levels from the emission-data vehicle with 
the applicable emission standards, apply deterioration factors to the 
measured emission levels. Section 1051.243 specifies how to test your 
vehicle to develop deterioration factors that represent the 
deterioration expected in emissions over your vehicle's full useful 
life.

[[Page 637]]

Your deterioration factors must take into account any available data 
from in-use testing with similar engines. Small-volume manufacturers may 
use assigned deterioration factors that we establish. Apply 
deterioration factors as follows:
    (1) For vehicles that use aftertreatment technology, such as 
catalytic converters, use a multiplicative deterioration factor for 
exhaust emissions. A multiplicative deterioration factor for a pollutant 
is the ratio of exhaust emissions at the end of the useful life and 
exhaust emissions at the low-hour test point. In these cases, adjust the 
official emission results for each tested vehicle or engine at the 
selected test point by multiplying the measured emissions by the 
deterioration factor. If the factor is less than one, use one. 
Multiplicative deterioration factors must be specified to three 
significant figures.
    (2) For vehicles that do not use aftertreatment technology, use an 
additive deterioration factor for exhaust emissions. An additive 
deterioration factor for a pollutant is the difference between exhaust 
emissions at the end of the useful life and exhaust emissions at the 
low-hour test point. In these cases, adjust the official emission 
results for each tested vehicle or engine at the selected test point by 
adding the factor to the measured emissions. If the factor is less than 
zero, use zero. Additive deterioration factors must be specified to one 
more decimal place than the applicable standard.
    (d) Collect emission data using measurements to one more decimal 
place than the applicable standard. Apply the deterioration factor to 
the official emission result, as described in paragraph (c) of this 
section, then round the adjusted figure to the same number of decimal 
places as the emission standard. Compare the rounded emission levels to 
the emission standard for each emission-data vehicle. In the case of 
HC+NOX standards, add the emission results and apply the 
deterioration factor to the sum of the pollutants before rounding. 
However, if your deterioration factors are based on emission 
measurements that do not cover the vehicle's full useful life, apply the 
deterioration factor to each pollutant and then add the results before 
rounding.

[70 FR 40496, July 13, 2005]