[Code of Federal Regulations]
[Title 40, Volume 29]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR610.33]

[Page 1004-1005]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 610_FUEL ECONOMY RETROFIT DEVICES--Table of Contents
 
                   Subpart C_Test Requirement Criteria
 
Sec. 610.33  Durability tests.

    The Administrator may determine that a device under evaluation will 
require durability testing in addition to the basic evaluation testing 
for device effectiveness. This requirement may be necessary for several 
reasons:
    (a) A retrofit device manufacturer may claim that some mileage 
accumulation may be needed before the full effectiveness of the device 
can be obtained. If such claims are made, durability testing as 
described in subpart E may be performed. To determine whether the 
effectiveness change during the mileage accumulation is a function of 
the device or of the mileage accumulation alone, in some durability 
tests it may be necessary to run the mileage accumulation on vehicles 
with and without the device. Due to the high cost of durability testing 
and in particular of such duplicate testing, it will be used only where 
it is judged by the Administrator to be necessary.
    (b) A device may have a limited life expectancy or be such that it 
requires replacement or adjustment at a prescribed mileage interval. 
Confirmatory durability tests may be run to assess whether such mileage 
intervals are proper and effective.
    (c) A device may be suspected of having an adverse effect on the 
durability of the engine to which it is applied. After identification of 
a potential failure mode, durability tests may be conducted to 
investigate any changes in engine characteristics associated with that 
failure mode. Examples are valve problems, deterioration in spark plug 
life, increase in carburetor or combustion chamber deposits, or 
increased engine wear. If it is not possible to directly measure the 
change in the suspect characteristic, then a durability run may be made 
as described in subpart E, in which fuel economy and exhaust emissions 
are periodically checked during the accumulation of up to 15,000 miles.
    (d) A critical item which can influence fuel economy is vehicle 
maintenance. Any durability test program used in evaluation of the 
effectiveness

[[Page 1005]]

of a fuel economy device will be designed to differentiate maintenance 
effects from the effect of the device. Any maintenance associated with 
the device operation will be rigidly controlled. If the maintenance 
appears to be a significant factor in the effectiveness of a device, 
then it may be necessary to run a control test on vehicles without the 
device installed where the same maintenance is performed to quantify any 
incremental effect of that maintenance.