[Federal Register Volume 62, Number 3 (Monday, January 6, 1997)]
[Notices]
[Pages 746-750]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-41]



[[Page 746]]

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ENVIRONMENTAL PROTECTION AGENCY

[FRL-5672-8]


Retrofit/Rebuild Requirements for 1993 and Earlier Model Year 
Urban Buses; Approval of a Notification of Intent to Certify Equipment

AGENCY: Environmental Protection Agency.

ACTION: Notice of Agency Certification of Equipment for the Urban Bus 
Retrofit/Rebuild Program.

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SUMMARY: The Agency received a notification of intent to certify 
equipment signed December 13, 1995, from Engine Control Systems Ltd. 
(ECS) with principal place of business at 165 Pony Dr., Newmarket, 
Ontario, Canada L3Y7V1 for certification of urban bus retrofit/rebuild 
equipment pursuant to 40 CFR 85.1401-85.1415. The equipment is 
applicable to petroleum-fueled Detroit Diesel Corporation (DDC) two-
cycle engines originally installed in an urban bus from model year 1979 
to model year 1993, exclusive of the DDC 6L71TA 1990 model year 
engines, all alcohol fueled engines, and models which were manufactured 
with particulate trap devices (see Table A). On August 8, 1996 EPA 
published a notice in the Federal Register that the notification had 
been received and made the notification available for public review and 
comment for a period of 45 days (60 F1 41408). EPA has completed its 
review of this notification, and the comments received, and the 
Director of the Engine Programs and Compliance Division has determined 
that it meets all the requirements for certification. Accordingly, EPA 
approves the certification of this equipment.
    The certified equipment provides 25 percent or greater reduction in 
exhaust emissions of particulate matter (PM) for the engines for which 
it is certified.
    The ECS notification, as well as other materials specifically 
relevant to it, are contained in Public Docket A-93-42, category XIV-A, 
entitled ``Certification of Urban Bus Retrofit/Rebuild Equipment''. 
This docket is located in room M-1500, Waterside Mall (Ground Floor), 
U.S. Environmental Protection Agency, 401 M Street SW, Washington, DC 
20460.
    Docket items may be inspected from 8:00 a.m. until 5:30 p.m., 
Monday through Friday. As provided in 40 CFR Part 2, a reasonable fee 
may be charged by the Agency for copying docket materials.

DATES: The effective date of certification is established in a letter 
to ECS dated December 9, 1996 for the equipment described in the ECS 
notification. This certified equipment may be used immediately by urban 
bus operators. Operators who have chosen to comply with program 1 or 
program 2 can utilize this equipment or other equipment that is 
certified for any engine that is listed in Table A that undergoes 
rebuild.

FOR FURTHER INFORMATION CONTACT: Anthony Erb, Engine Compliance 
Programs Group, Engine Program & Compliance Division (6403J), U.S. 
Environmental Protection Agency, 401 M St. SW, Washington, D.C. 20460. 
Telephone: (202) 233-9259.

SUPPLEMENTARY INFORMATION:

I. Background

    By a notification of intent to certify signed December 13, 1995, 
ECS applied for certification of equipment applicable to petroleum-
fueled Detroit Diesel Corporation (DDC) two-cycle engines originally 
installed in an urban bus from model year 1979 to model year 1993, 
exclusive of the DDC 6L71TA 1990 model year engines and models which 
were manufactured with particulate trap devices or alcohol fueled (see 
Table A). The notification of intent to certify states that the 
equipment being certified is an oxidation converter muffler (OCM). The 
OCM contains an oxidation catalyst developed specifically for diesel 
applications, packaged as a direct replacement for the muffler. The 
application demonstrates that the candidate equipment provides a 25 
percent or greater reduction in emissions of particulate matter (PM) 
for petroleum fueled diesel engines relative to an original engine 
configuration with no after treatment installed. Certification is 
applicable to engines that are rebuilt to original specifications, or 
in-use engines that are not rebuilt at the time the OCM is installed 
provided the engine meets engine oil consumption limits specified by 
ECS. ECS is also certifying a 25 percent reduction in PM for engines 
that are retrofit/rebuilt with certified rebuild kits that do not 
include after treatment devices if the OCM is installed at the same 
time the retrofit/rebuild occurs. Currently, this applies to the DDC 
retrofit/rebuild kit which was certified on October 2, 1995 (60 FR 
51472) for the 6V92TA MUI model and to the kit certified on July 19, 
1996 (61 FR 37738) for the 6V92TA DDEC II model.
    Certification of the OCM does not trigger any new program 
requirements for applicable engines, because the requirement to use 
equipment certified to achieve at least a 25% reduction has already 
been triggered for these engines.
    Using engine dynamometer testing in accordance with the Federal 
Test Procedure for heavy-duty diesel engines on a 1991 DDC 6V92TA DDEC 
II engine, ECS documented a 26% reduction in PM emission after 
retrofit. The test results for this engine with the certified retrofit 
equipment installed meet applicable Federal emission standards for 
hydrocarbon (HC), carbon monoxide (CO), oxides of nitrogen (NOx), and 
smoke emissions. In chassis testing performed over the Central Business 
District (CBD) sequence on a 1987 DDC 6V71N engine, ECS demonstrated a 
42% PM emission reduction after retrofit. Using chassis testing 
performed over the New York Composite (NYC) sequence on this same 
engine, ECS demonstrated a 37% reduction in PM emission.
    Table A provides the PM emission certification levels for the ECS 
equipment for the specified models and model years.

                                         Table A.--Certification Levels                                         
----------------------------------------------------------------------------------------------------------------
                                                                             PM Level                           
                                                                            \2\with OCM                         
             Engine models                   Model year         PM Level      and DDC          Code/Family      
                                                                \1\ with     Certified                          
                                                                  OCM       Rebuild kit                         
----------------------------------------------------------------------------------------------------------------
6V92TA MUI............................  1979-87.............         0.38          0.22  All.                   
                                        1988-1989...........         0.23          0.17  All.                   
6V92TA DDEC I.........................  1986-87.............         0.23           N/A  All.                   
6V92TA DDEC II........................  1988-90.............         0.23          0.17  All.                   
                                        1991................         0.23           N/A                         
                                        1992-93.............         0.19           N/A  All.                   

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6V71N.................................  1973-89.............         0.38           N/A  All.                   
6V71T.................................  1985-86.............         0.38           N/A  All.                   
6L71TA................................  1988-89.............         0.23           N/A  All.                   
6L71TA DDEC...........................  1990-91.............         0.23           N/A  All.                   
----------------------------------------------------------------------------------------------------------------
\1\ The original PM certification levels for the 1991 6V92TA DDEC II, and 6L71TA DDEC engine models are based on
  Family Emission Limits (FELs)under EPA's averaging, banking and trading program (AB&T). These limits are      
  higher than the 1991 PM standard of 0.25 g/bhp-hr. The PM level listed in this table for the engines that are 
  equipped with the OCM provide at least a 25% reduction from the FEL. The 1992 to 1993 6V92TA DDEC II engine   
  models were also certified using FELs under the AB&T program and likewise the PM levels for the engines       
  equipped with the OCM represent at least a 25% reduction from the FEL.                                        
\2\ For 6V92TA MUI and 6V92TA DDEC II models that are rebuilt using a certified DDC emissions retrofit kit, ECS 
  is certifying the PM engine emissions to reduced levels as provided in Table A. provided the OCM is installed 
  at the same time the rebuild with the certified DDC upgrade kit takes place. The DDC upgrade kit certification
  notifications were published in the Federal Register on October 2, 1995 (60 FR51472) and July 19,1996 (61     
  FR37738) respectively.                                                                                        

    Under Program 1, all rebuilds or replacements of applicable engines 
must use equipment certified to reduce PM levels by at least 25 
percent. This requirement will continue for the applicable engines 
until such time as it is superseded by equipment that is certified to 
trigger the 0.10 g/bhp-hr emission standard for less than a life cycle 
cost of $7,940 (in 1992 dollars).
    ECS has established PM certification levels as specified in Table A 
for this equipment. Operators who choose to comply with Program 2 and 
install this equipment, will use the specified PM emission levels in 
their calculation of fleet level attained.

II. Summary and Analysis of Comments

    EPA received comments from two parties on this notification. The 
Detroit Diesel Corporation (DDC) had a number of comments in the 
following areas: test engine selection, extrapolation of test results, 
reductions in non-volatile particulate matter, certification of 
equipment for use on different stages of engine rebuild, certified 
emission levels, incomplete parts listing and representivity of test 
data. The Engelhard Corporation commented on the following areas: worst 
case demonstration, incomplete parts listing, representivity of test 
data to cover all engines and types, and the ability of the OCM to 
reduce PM emissions.
    DDC stated that the test configuration of the 1991 DDC 6V92TA DDEC 
II engine was not clearly documented and that the original 
configuration of the test engine was a 1992 code 4T engine intended for 
use with a particulate trap. DDC questioned the relevance of testing 
performed on an engine with a unique calibration originally intended 
for use on trap equipped engines. DDC noted that test data it developed 
during new engine certification testing for the 1991 4C rating (a non-
trap configuration) had a total PM level of 0.218 g/bhp-hr with a 
soluble fraction (SOF) of 21.5%. DDC questioned how this engine could 
be considered ``worst case''. Given that oxidation catalysts primarily 
reduce the SOF portion of PM, DDC questioned whether the OCM could 
reduce PM emissions on the 1991 code 4C rating by 25% when the entire 
SOF fraction is only 21.5%.
    Based on the information presented by ECS, it is unclear whether 
the engine rating at the time of testing was in the 4T or the 4C 
configuration. It was not clear from ECS that the engine had been 
converted from it's original 4T rating. Also, background historical 
information for this engine could not be provided. Since there is 
nothing in the record which indicates that the engine was converted to 
the 4C configuration, the Agency assumes that it was tested in the 
original 4T configuration. Therefore, it is apparent that DDC's 
comments relative to SOF content of the 4C configuration relative to 
the test performed on the 4T configuration would not be relevant in the 
certification being discussed. However, it is noted that because an 
oxidation catalyst mainly reduces only the SOF portion of PM, it would 
not be possible to obtain a 25% reduction in PM for any engine for 
which the SOF portion of PM is less than 25%. EPA requests information 
from industry and the general public with regard to the percentage of 
SOF that particular in-use engines produce. This information would be 
considered for the certification being discussed in this notice and in 
regard to the previous certifications of oxidation catalysts under the 
urban bus retrofit/rebuild program.
    In regard to DDC's and Engelhard's contention that the 1991 6V92TA 
DDEC II engine would not represent the worst case according to the 
regulations, EPA agrees. However, the 1987 6V71N does qualify as a 
``worst case'' engine for testing purposes under the urban bus retrofit 
regulations, and test results from this engine provide the basis for 
the certification discussed herein.
    DDC questioned the relevancy of the chassis dynamometer test 
results obtained on the 6V71N engine using the Central Business 
District (CBD) and New York Composite (NYC) cycles and noted that EPA 
should not rely on the chassis test results in assessing whether the 
OCM technology meets requirements to reduce PM emission by 25%. In 
response, the regulations allow a certifier to use chassis based test 
procedures representative of typical urban bus operation to show 
compliance with the 25% or greater PM reduction requirement. The CBD 
simulates stop and go performance of urban buses in the city and the 
NYC was incorporated to represent some higher average speeds not seen 
in the CBD which an urban bus may on occasion encounter. After review, 
EPA found the proposed chassis testing plan to be acceptable and 
approved the use of chassis testing to demonstrate the 25% reduction in 
PM.
    EPA agrees with the comment from Engelhard and DDC that it is 
tenuous to base certification of OCMs, intended for engines using non-
particulate trap ratings, on testing where the 4T-trap based rating was 
utilized. However, ECS provided acceptable chassis test results 
performed on a non-trap engine that demonstrate reduction of PM by at 
least 25%.
    Engelhard also stated that the reduction of 26% demonstrated on the

[[Page 748]]

6V92TA DDEC II engine does not demonstrate a sufficient margin beyond 
the 25% level to account for in-use deterioration of the catalyst over 
the 150,000 mile performance warranty period. EPA finds that the 
results of this test are not conclusive because the engine 
configuration tested apparently does not represent an urban bus engine 
that could be used to demonstrate PM reduction under the retrofit/
rebuild program since it was apparently in a calibration for a 
particulate trap equipped engine. However, chassis testing data 
presented by ECS shows a decrease in PM of at least 37% providing ample 
margin beyond the required 25% reduction.
    In the notification, ECS sought to use the OCM kit on engines which 
were not in need of rebuild at the time of OCM installation based on a 
review of specified engine conditions. DDC commented that certification 
should be approved only with respect to engines that have been rebuilt 
to original specifications as the retrofit/rebuild requirements do not 
apply until the operator rebuilds an engine. DDC agreed that under 
Program 2 operators could conceivably install certified add-on 
equipment without rebuilding the base engine and use the certified 
emission level in their fleet averaging, but expressed concerns that 
the engine may have worn cylinders or fuel injection components in need 
of rebuild and, as a result, the engine out PM emissions may be high. 
DDC stated that engine wear conditions would create difficulty in 
achieving the certification level when applying the OCM to an engine 
which has not been rebuilt.
    DDC's claim that program requirements do not apply until an 
operator rebuilds an engine concerns compliance programs. Operators 
choosing to comply with Program 1 are not required to take any action 
until an affected engine is rebuilt or replaced. However, operators 
choosing to comply with Program 2 must ensure their fleet is equal to 
or less than their target fleet level at all times. Thus, program 
requirements apply continuously to Program 2 operators. In addition, if 
an operator desires to be able to change between programs, the 
regulations require that both programs be complied with prior to the 
switch.
    While it is true that Program 1 requirements become effective when 
the engine is rebuilt, EPA encourages the installation of certified 
equipment prior to the time it is required under the regulations in 
accordance with the manufacturer's instructions.
    In regard to DDCs' concern that engine wear needs to be evaluated 
prior to installing this equipment, ECS has modified its application to 
remove the language referring to ``specified engine calibrations'' 
which DDC stated was vague and unenforceable and will instead require 
that operators determine the oil consumption rate for an engine to 
determine engine wear and condition prior to installing the OCM. If the 
rate of oil consumption exceeds 1.5 quarts of consumption per 10 hours 
of operation, ECS will require that the engine be rebuilt prior to OCM 
installation. Furthermore, ECS is responsible for meeting the 
performance warranty for a period of 150,000 miles for each engine 
under this certification. EPA believes that operators will rebuild 
engines when necessary in order to keep their fleet in reasonable 
operating condition. The decision to rebuild will not be affected by 
the option to install a catalyst. Rather, operators will only choose to 
install the catalyst in order to reduce emissions, and not in place of 
a needed rebuild. It is noted that the chassis testing data presented 
demonstrates a 37% to 42% reduction in the case where the engine was 
rebuilt. Based on these levels of reduction, it is apparent there 
should be ample margin between the in-use emissions of an engine that 
the operator finds is not in need of a rebuild to reasonably project 
that the levels stated in Table A can be met.
    DDC questioned reported reductions in the non-volatile PM fraction 
with the OCM, noting that it is commonly accepted that oxidation 
catalysts are effective in oxidizing volatile particulate, but have 
little effect on the non-volatile component. In response, ECS explains 
that effective diesel oxidation catalysts will have some activity 
towards reduction of the non-volatile or insoluble portion of diesel 
particulate. This activity allows the catalyst to clean itself from 
carbon build-up and prevents catalyst fouling, particulate build-up and 
eventual plugging of the substrate. ECS also stated that it is 
important to recognize that, in the measurements taken, the volatile 
organic fraction and non-volatile organic fractions were made using the 
direct filter injection gas chromatography analysis DFI/GC technique 
developed by Southwest Research Institute. Using this procedure some 
small amount of high molecular weight solubles that did not volatize 
may exist in the unvolatized particulate sample which would account for 
the reduction seen. ECS stated that since diesel engine oxidation 
catalysts all operate on the same basic principle, the points being 
made relative to volatile vs. non-volatile components of urban bus PM 
emissions apply to the industry as a whole and should not be confined 
to the ECS certification review process. EPA concurs that this issue 
should be addressed on an industry-wide basis. Further, EPA does not 
have sufficient information to resolve this issue based on the comments 
submitted. Therefore, EPA requests that industry and the public provide 
any additional information on this matter so that resolution may be 
reached in the future.
    DDC and Engelhard commented that the rebuild on the 6V71N engine 
appeared to be incomplete. DDC noted that the rebuild performed did not 
include fuel injectors, piston rings, or cylinder liners all of which 
would be replaced during a normal rebuild and which, if not replaced, 
would cause inflated PM levels. DDC stated that if the Agency is to 
rely on the chassis test data for certification of the OCM, it should 
first make certain that it was properly rebuilt to the original engine 
configuration prior to the testing. In response, ECS has provided 
additional documentation that the piston rings, cylinder liners and 
injectors were replaced at the time of rebuild and that the engine was 
rebuilt to standard specifications. The failure to include this in the 
original notification materials was an oversight.
    With regard to certified emission levels, DDC commented that the 
proposed certification levels do not represent a full 25% reduction. 
For example, for the 1991 6V92TA DDEC engine codes 3C and 4C, the 
original certification testing yielded PM emission levels of 0.25 and 
0.22 g/bhp-hr, respectively, and the proposed certification level of 
0.23 g/bhp-hr given in Table A represents only a 8% reduction on 
average from the original certification test levels.
    In response, the pre-rebuild levels listed in section 85.1403 
(c)(1)(iii)(A) were determined by EPA based on certification results or 
engineering data and judgement. In Table A, of today's notice, ECS has 
listed the PM levels to which it is certifying for listed models and 
years. In a number of instances the certification levels shown 
represent a 25% reduction from the pre-rebuild levels that were listed 
in section 85.1403(c)(1)(iii)(A) or the regulations. In other 
instances, the number reflects a 25% reduction from the level that was 
certified by DDC during new engine certification.
    In the case of the 1991 6V92TA DDEC II 4C engine configuration, the 
new engine certification testing by DDC yielded a PM emission level of 
0.22 g/bhp-hr. However, DDC certified the engine to a family emission 
level (FEL)

[[Page 749]]

of 0.30 g/bhp-hr. The certification level of 0.23 g/bhp-hr PM provides 
for more than a 25% reduction from the original DDC certification level 
or FEL for this engine and from the pre-rebuild level of section 
85.1403(c). In previous urban bus retrofit/rebuild certifications, EPA 
has based certification on the FEL which the original manufacturer 
certified to meet in-use. In fact, the ECS certification levels for the 
models listed are identical to those for which oxidation catalyst kits 
have been certified to date. In declaring a FEL, the engine 
manufacturer states the emission level it will achieve in-use. That is 
to say, even though the certification test level is determined, the 
engine manufacturer declares a different emission level that it can 
meet in-use. Because the urban bus retrofit/rebuild program applies to 
in-use buses, and since the rebuild certifier is certifying that a 
rebuilt engine with the retrofit equipment will meet the rebuild 
certification level during the warranty period, it makes sense to apply 
the in-use certification level or FEL as a basis for the reduction. To 
require certifiers of urban bus retrofit/rebuild equipment to reduce 
emissions from an initial level that the original manufacturer did not 
use during the original certification would not be reasonable. As 
stated, EPA used the FEL as a basis for the 25% reduction in previous 
decisions. EPA does not believe it would be reasonable to change the 
basis for the 25% reduction as DDC has requested.
    DDC noted that in order to ensure optimum engine performance, 
emissions durability and fuel economy, DDC specifies maximum exhaust 
back pressure limits for all DDC engines. DDC noted that there was a 
small backpressure increase during testing and questioned whether the 
catalyst used in testing had been aged prior to the test. DDC also 
noted that the instructions to be given to operators did not include 
backpressure specifications or procedures for checking backpressure 
after the catalyst is installed. ECS has stated that careful attention 
will be paid to optimizing the exhaust backpressure to a level 
comparable to the original muffler. The catalyst used during testing 
was aged or degreened to provide representative in-use performance. ECS 
stated that it does not anticipate that checking the backpressure 
should be required under normal circumstances. However, the converter 
mufflers certified in this notice and produced by ECS include a port to 
allow in-use backpressure checks and ECS has developed a procedure for 
checking and cleaning the converter muffler that will be distributed to 
operators who purchase the kit.
    DDC commented that EPA should seek assurances that the certified 
hardware will be available for all engine bus combinations. ECS has 
indicated it has completed design work on the majority of converter 
mufflers required for this market. If any specific design should be 
encountered for which a converter muffler cannot be provided which will 
meet the performance criterion, it will be reported to EPA. This 
coupled with the fact that other companies have already certified 
equipment for the engines covered under this application should provide 
adequate coverage of the marketplace.
    Engelhard commented that because thermal insulation was required on 
the pre-catalyst exhaust on testing performed on the 6V92TA DDEC II 
engine, insulation should be required on all pre-catalyst components 
for ECS converter mufflers to be covered by certification. In response, 
ECS explained that no insulation was used during the chassis tests 
performed on the 6V71 engine for which PM reductions were demonstrated. 
Insulation of the exhaust system is not necessary for OCM installation 
on 6V71, 6V92 and 6L71 mechanical engine families as the exhaust 
temperatures are sufficient for proper unit function. For the engine 
dynamometer testing performed on the 6V92TA DDEC II engine, the entire 
exhaust system was insulated. ECS subsequently performed additional 
testing which indicates that the temperature loss between the 
turbocharger and converter muffler is insignificant and that insulation 
on the piping between the turbocharger outlet and the converter muffler 
is not needed. However, ECS has determined that the actual converter 
muffler must be insulated in order to maintain minimum catalyst 
temperature for the DDEC II engine. Accordingly, ECS has designed all 
converter mufflers for use on these engines to include either 
insulation located within the muffler shell or via an external wrap/
blanket over the muffler casing.
    Engelhard raised a concern based on the different exhaust 
temperature profiles and engine out emissions that exist relative to 
engines that are naturally aspirated, turbo charged or turbo-charged 
after-cooled engines. Engelhard questioned whether an engine that 
achieves a 25% reduction on a naturally aspirated engine could achieve 
the same on a turbo-charged engine. Engelhard stated that without a 
demonstration that 25% reduction in total PM could be obtained on all 
versions of the 6V71, engine certification should not be granted for 
all engines. Unfortunately, while Engelhard raised some interesting 
questions in this area, it did not provide any data or information on 
catalyst efficiency as it relates to different temperatures that could 
be used to substantiate its claim. At this point, EPA does not have 
information which would lead it to conclude that the ECS catalyst would 
not be able to provide the 25% reduction on the models it has 
identified. However, it is noted that in testing the 1991 6V92TA DDEC 
II engine, ECS provides information that the OCM reduces emissions by 
26% on an engine where the temperature reached a maximum of 320 degrees 
Centigrade. These results address the concern relative to the ability 
of the OCM to reduce PM emissions on engines that operate at the lower 
end of the temperature spectrum. In regard to the issue of differing 
emission rates, EPA needs information to conclusively deal with this on 
an industry-wide basis and EPA welcomes such information from the 
public and industry.
    DDC commented that certification of the ECS equipment should not 
cause DDC to have additional liability. DDC cited language in the 
preamble to the final rule published in the Federal Register on April 
21, 1993, page 21381. DDC's concern was centered around the following 
statement, ``* * * However, if an engine manufacturer supplies 
retrofit/rebuild equipment, it is responsible for the emissions 
performance of the equipment.'' DDC suggested that it was EPA's intent 
to make engine manufacturers accept additional liability for rebuild 
hardware which they sell and which is subsequently used in a rebuild 
which has been approved under the program. The statement simply means 
that if the engine manufacturer supplies retrofit equipment as part of 
a certified rebuild kit (such as the DDC certified upgrade kit) then 
the manufacturer is responsible for the warranties associated with the 
retrofit/rebuild regulations. If, on the other hand, the manufacturer 
sells equipment for rebuild through its normal sales process, and such 
sale is not part of a certified kit with which the manufacturer is 
affiliated, the manufacturer is not liable for equipment performance 
beyond its normal liability. That is to say, for equipment not sold by 
the manufacturer to be included in a certified kit under the retrofit/
rebuild program, the manufacturer is not responsible for the defect 
warranty or the performance warranty that is associated with the 
retrofit/rebuild program. The retrofit/rebuild equipment

[[Page 750]]

certifier, however, is responsible for these warranties.

III. Certification Approval

    The Agency has reviewed this notification, along with comments 
received from interested parties, and finds that the equipment 
described in this notification of intent to certify:
    (1) Reduces particulate matter exhaust emissions by at least 25 
percent, without causing the applicable engine families to exceed other 
exhaust emissions standards;
    (2) Will not cause an unreasonable risk to the public health, 
welfare, or safety;
    (3) Will not result in any additional range of parameter 
adjustability; and,
    (4) Meets other requirements necessary for certification under the 
Retrofit/Rebuild Requirements for 1993 and Earlier Model Year Urban 
Buses (40 CFR Sections 85.1401 through 85.1415). The Agency hereby 
certifies this equipment for use in the urban bus retrofit/rebuild 
program as discussed below in section IV.

IV. Operator Requirements and Responsibilities

    This equipment may be used immediately by urban bus operators who 
have chosen to comply with either Program 1 or Program 2, but must be 
properly applied. Currently, operators having certain engines who have 
chosen to comply with Program 1 must use equipment certified to reduce 
PM emissions by 25 percent or more when those engines are rebuilt or 
replaced. Today's Federal Register notice certifies the above-described 
ECS equipment as meeting that PM reduction requirement. Only equipment 
that has been certified to reduce PM by 25% or more may be used by 
operators with applicable engines who have chosen Program 1. Urban bus 
operators who choose to comply with Program 1 may use the certified ECS 
equipment (or other certified equipment) until such time as the 0.10 g/
bhp-hr standard is triggered for the applicable engines.
    Operators who choose to comply with Program 2 and use the ECS 
equipment will use the appropriate PM emission level from Table A when 
calculating their fleet level attained (FLA).
    As stated in the program regulations (40 CFR 85.1400 through 
85.1415), operators are required to maintain records for each engine in 
their fleet to demonstrate that they are in compliance with the program 
requirements beginning January 1, 1995. These records include purchase 
records, receipts, and part numbers for the parts and components used 
in the rebuilding of urban bus engines.
Richard D. Wilson,
Acting Assistant Administrator for Air and Radiation.
[FR Doc. 97-41 Filed 1-3-97; 8:45 am]
BILLING CODE 6560-50-P