[Federal Register Volume 63, Number 93 (Thursday, May 14, 1998)]
[Notices]
[Pages 26798-26806]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-12850]


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ENVIRONMENTAL PROTECTION AGENCY

[FRL-6013-8]


Retrofit/Rebuild Requirements for 1993 and Earlier Model Year 
Urban Buses; Certification of Equipment

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of EPA certification of equipment provided by Detroit 
Diesel Corporation.

-----------------------------------------------------------------------

SUMMARY: Today's Federal Register notice announces EPA's decision to 
certify equipment to the 0.10 g/bhp-hr standard for the Urban Bus 
Retrofit/Rebuild Program. The equipment is provided by the Detroit 
Diesel Corporation (DDC).
    DDC submitted to EPA a notification of intent to certify equipment, 
in materials signed July 16, 1997, pursuant to the program regulations 
at 40 CFR Part 85, Subpart O. On November 6, 1997, EPA published a 
notice in the Federal Register that the DDC notification had been 
received and made the notification available for public review and 
comment for a period of 45 days (62 FR 60077). EPA has completed its 
review and the Director of the Engine Programs and Compliance Division 
has determined that it meets all requirements for certification. 
Therefore, EPA certified this equipment in a letter to DDC dated April 
6, 1998.
    The equipment consists of the base engine components used on the 
25% reduction retrofit/rebuild kit certified by DDC, components from 
the 25% retrofit catalyst kit certified by Engine Control Systems, Ltd. 
(ECS) and a TurboPac supercharger system supplied by Turbodyne Systems, 
Inc. that supplies additional air for combustion during engine 
acceleration.
    The kit is applicable to 6V92TA urban bus engine models made by 
Detroit Diesel Corporation (DDC) from model years 1979 to 1989 and 
equipped with mechanical unit injectors (MUI), and may be used 
immediately by transit operators in compliance with program 
requirements. The kit would be available in three horsepower levels 
(253, 277, and 294).
    EPA has determined that this DDC kit complies with the 0.10 gram 
per brake horsepower-hour (g/bhp-hr) particulate matter (PM) standard 
for the applicable engines. EPA has not determined that DDC's 
notification complies with the life cycle cost requirements of the 
program regulations because no life cycle costs were supplied with the 
application.
    Today's Federal Register notice does not trigger any additional 
program requirements for transit operators. The 0.10 g/bhp-hr PM level 
has already been triggered for all engines covered by this 
notification.
    The notification of intent to certify, as well as other materials 
specifically relevant to it, are contained in Category XX-A of Public 
Docket A-93-42, entitled ``Certification of Urban Bus Retrofit/Rebuild 
Equipment.'' This docket is located at the address listed below.
    Additional details concerning this certification, the DDC's kit, 
and responsibilities of transit operators, are provided below.

DATES: EPA certified this equipment in a letter to DDC dated April 6, 
1998. Today's Federal Register notice announces this certification. The 
0.10 g/bhp-hr standard was triggered on March 14, 1997 (62 FR 12166) 
for all engines covered by this certification.

ADDRESSES: The DDC notification, as well as other material specifically 
relevant to it, are contained at the U.S. Environmental Protection 
Agency's Public Air Docket A-93-42 (Category XX-A), Room M-1500, 401 
``M'' Street SW, Washington, DC 20460.
    The DDC notification of intent to certify, as well as other 
materials specifically relevant to it, are contained in the public 
docket indicated above. 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 EPA for copying docket materials.

FOR FURTHER INFORMATION CONTACT: Anthony Erb, Engine Programs and 
Compliance Division (6403J), U.S. Environmental Protection Agency, 401 
``M'' St. SW, Washington, D.C. 20460. Telephone: (202) 564-9259.

SUPPLEMENTARY INFORMATION:

I. Description of the Certified Kit

    The certified kit described in today's Federal Register notice is 
provided by DDC. It is certified to the 0.10 g/bhp-hr standard but does 
not comply with the applicable life cycle cost requirements of the 
program. No cost data was provided in the notification.
    The certification described in today's notice applies to 1979 
through 1989 model year DDC 6V92TA engines that are equipped with 
mechanical unit injectors (MUI) and certified to federal emissions 
standards. It does not apply to engines certified to California 
emissions standards. The impact of this decision on transit operators 
is discussed in more detail in the ``Transit Operator Requirements'' 
section below.

[[Page 26799]]

    The kit, described further below, consists of base engine 
components used on the 25% reduction kit certified by DDC earlier, a 
catalytic exhaust muffler supplied by Engine Control Systems, Ltd. 
(ECS), and a TurboPac supercharger system supplied by Turbodyne 
Systems, Inc. that supplies additional combustion air during 
acceleration. The kit is available in three horsepower (hp) ratings 
(253, 277, and 294 hp).
    For retrofit with the DDC kit, an engine is rebuilt in accordance 
with standard DDC rebuild procedures, using specified engine 
components. This component set essentially includes the equipment 
certified by EPA to provide a 25% particulate reduction on October 2, 
1995, at 60 FR 51472. These components are provided in two separate 
sets of parts. The first set of components is comprised of newly 
manufactured parts, including a gasket kit, air inlet hose, cylinder 
kits (piston assemblies and cylinder liners) a by-pass valve and a 
truck type throttle delay. The second set of components includes 
Reliabilt <SUP>TM</SUP> remanufactured parts, including the fuel 
injectors, camshafts, blower assembly, turbocharger, and head 
assemblies. Kit usage is based on engine rotation (righthand (RH) or 
lefthand (LH)), engine orientation, right bank cam gear mounting (bolt 
or nut), and engine power output based on injector size. The only 
difference from the previously certified equipment according to DDC is 
the inclusion of a truck-style throttle delay, adjustment of the 
throttle delay and injector timing settings to improve driveability. 
Additionally, the cylinder kit components have been modified to improve 
durability.
    The converter is the same size and shape as the catalytic converter 
muffler certified by ECS for the Urban Bus Program as described in the 
Federal Register on January 6, 1997 (61 FR 746), is a direct 
replacement for the original equipment muffler, and is designed to fit 
the specific bus/engine combination. The use of diesel fuel that has 
been mixed with crankcase oil is prohibited by DDC.
    The third constituent of the kit consists of an electrically 
powered supercharger system which is supplied by Turbodyne Systems, 
Inc. This component set, referred to as the TurboPac <SUP>TM</SUP> 
supplies additional intake air during engine acceleration from low 
engine speeds. DDC states that in addition to decreasing PM emissions 
and visible smoke during engine acceleration, the supercharger also 
improves engine response and vehicle driveability by reducing the fuel 
modulation during acceleration. The basic system consists of a 
supercharger blower, a diverter valve, a boost pressure sensor, an 
electrical control box and power cables, and a throttle switch for 
detecting the start of the engine acceleration mode, and will be 
supplied in two kits. One includes those components common to all 
installations and a second kit to accommodate the installation 
requirements of the various engine and vehicle configurations.
    To complete an engine rebuild two (2) base engine component kits, 
one (1) converter muffler kit, and two (2) supercharger kits are 
required. The specific kits used will depend on the engine/vehicle 
combination.
    DDC states there are no differences in the service intervals or 
maintenance practices for the base engine associated with the 
installation of the upgrade kit. The converter/muffler requires no 
regularly scheduled maintenance, only an occasional cleaning if the 
maximum back pressure of the exhaust system is exceeded. The 
supercharger does not require scheduled maintenance; however, a visual 
inspection for air leaks is recommended whenever the engine is 
serviced.
    Standard procedures as described in the service manual for 92 
Series engines are to be used when rebuilding the base engines using 
the candidate equipment. No unique rebuild procedures are required.
    Use of the candidate kit is restricted to 6V92TA Detroit Diesel 
Corporation engines manufactured from January 1979 through December 
1989, equipped with mechanical unit fuel injectors (MUI), and 
originally certified to meet Federal emission standards. The required 
fuel is low sulphur (0.05% max by weight) diesel fuel, either number 1 
or number 2. Complete rebuild kits will be sold by DDC through normal 
distribution channels.
    All of the testing presented by DDC for this certification was 
conducted using original equipment (OE) parts, except for the converter 
muffler and the TurboPac components. EPA has no assurance that engines 
rebuilt using parts that are not (OE) would comply with the 0.10 g/bhp-
hr standard. Therefore, use of engine parts that are not the specified 
OE parts are not covered by the certification described in today's 
Federal Register notice.
    Pursuant to 40 CFR 85.1409, DDC will provide a 100,000-mile defect 
warranty and a 150,000-mile emissions performance warranty for the kit, 
and all of its components.
    EPA's certification of the Engelhard Corporation's ETX 
<SUP>TM</SUP> kit (62 FR 12166; March 14, 1997) triggered the 0.10 g/
bhp-hr standard for 1979-1989 6V92TA MUI engines. That kit provided the 
three power ratings: 253, 277, and 294 hp that are included in this 
certification. Consequently, the certification of the DDC kit described 
in today's Federal Register notice, does not trigger the 0.10 g/bhp-hr 
standard for engines included in the certification.

II. Background and Basis for Certification

    In a notification of intent to certify equipment, composed of an 
initial document signed July 16, 1997 and subsequent documents, DDC 
applied for certification of the kit under the Environmental Protection 
Agency's (EPA) Urban Bus Retrofit/Rebuild Program. Engines applicable 
to the certified kit are 6V92TA urban bus engine models made by Detroit 
Diesel Corporation (DDC) from model years 1979 to 1989 that are 
equipped with mechanical unit injectors (MUI) and certified to, or 
rebuilt to, comply with federal emissions standards. The certifier's 
principal place of business is: Detroit Diesel Corporation, 13400 Outer 
Drive, West, Detroit, Michigan 48329-4001.
    Using engine dynamometer (transient) testing in accordance with the 
Federal Test Procedure for heavy-duty diesel engines, DDC demonstrated 
compliance with the 0.10 g/bhp-hr particulate matter (PM) emissions 
standard. Engine dynamometer data, shown below in Table A, is the basis 
for the certification approval of the kit when used on applicable 
engines. The emissions test data is part of DDC's notification of 
intent to certify, which is available in the public docket located at 
the above-mentioned address. All testing was conducted using #2 low-
sulfur diesel fuel.

                   Table A.--Exhaust Emissions Summary                  
------------------------------------------------------------------------
                                                    g/bhp-hr            
                                       ---------------------------------
     Gaseous and particulate test                                6V92TA 
                                          1989 HDDE standards   MUI with
                                                                 DDC kit
------------------------------------------------------------------------
HC....................................  1.3...................       0.1
CO....................................  15.5..................       0.4
NO<INF>X...................................  10.7..................       9.8
PM....................................  0.60..................     0.091
BSFC \1\..............................  ......................     0.464
Smoke Test:                             Standards.............  ........
  ACCEL...............................  20%...................      3.3%
  LUG.................................  15%...................      2.5%
  PEAK................................  50%...................      4.2%
------------------------------------------------------------------------
\1\ Brake Specific Fuel Consumption (BSFC) is measured in units of lb/  
  bhp-hr.                                                               


[[Page 26800]]

    The exhaust emissions data presented by DDC is from testing a 
Detroit Diesel Corporation (DDC) engine model 6V92TA, in accordance 
with procedures set forth at 40 CFR Part 86, Subparts N and I. The 
engine model was tested after being equipped with the DDC kit. The 6V92 
engine was tested in one horsepower (hp) rating: 277hp.
    The data of Table A demonstrates that the test engine, when rebuilt 
with the DDC kit, PM emissions are less than 0.10 g/bhp-hr and, 
emissions of hydrocarbon (HC), carbon monoxide (CO), NO<INF>X</INF> and 
smoke opacity are within applicable federal standards.
    This action applies a PM emissions level of 0.10 g/bhp-hr to all 
1979 through 1989 DDC 6V92TA MUI urban bus engines, when properly 
equipped with the DDC kit and when using either diesel fuel #1 or #2. 
Table B lists the applicable engine models and certification levels 
associated with the certification announced in today's Federal 
Register.

                Table B.--Certification Level of DDC Kit                
------------------------------------------------------------------------
                                                       Certification PM 
         Engine  models              Engine codes            level      
------------------------------------------------------------------------
1979-1989 DDC 6V92TA MUI........  All certified to    0.10 g/bhp-hr.    
                                   meet federal                         
                                   emissions                            
                                   standards.                           
------------------------------------------------------------------------

    All engines for which the DDC kit is intended to apply are expected 
to meet the 0.10 g/bhp-hr PM standard because the kit instructs the 
rebuilder to replace all emissions-related parts during the rebuild 
with DDC specified parts included in the kit, install the converter 
muffler and install the TurboPac system. The engine-out emissions level 
(upstream of the catalyst) is expected to be predictable because all 
emission-related parts are replaced using the DDC specified emissions-
related parts and settings of the kit. As demonstrated by the test 
engine, the combination of the specified parts, the specified settings 
of the kit, the converter muffler and the TurboPac system, result in a 
PM level less than 0.10 g/bhp-hr.
    A life cycle cost analysis is necessary only for certification of 
equipment that is meant to trigger a program emissions standard. 
Certification of Engelhard Corporation's ETX<SUP>TM</SUP> kit triggered 
the 0.10 g/bhp-hr standard for 6V92TA MUI engines, and made available 
kits rated at 253, 277, and 294 hp. The DDC certification does not 
include a cost analysis and one is not necessary for this 
certification. DDC states that engines equipped with the kit will have 
no additional maintenance or service requirements.

III. Summary and Analysis of Comments and Concerns

    Comments were received from five parties in response to the Federal 
Register notice of November 6, 1997 (62 FR 60077). The commenters are 
Johnson Matthey Incorporated (JMI), Engelhard Corporation (Engelhard), 
the Washington Metropolitan Area Transit Authority (WMATA), the 
Maryland Department of Transportation Mass Transit Administration 
(MTA), and the Milwaukee County Transit System (MCTS). JMI and 
Engelhard provided extensive comment. JMI is a manufacturer of 
equipment certified to meet the 0.10 g/bhp-hr standard for the 1979-
1989 6V92TA MUI engines (see 62 FR 60079; November 6, 1997). Engelhard 
is the manufacturer of equipment certified under the urban bus program 
that triggered the 0.10 g/bhp-hr standard for the 1979-1989 6V92TA MUI 
engines (see 62 FR 12166; March 14, 1997). WMATA, the MTA, and the MCTS 
are large transit bus operators in major metropolitan areas, which are 
subject to requirements of the urban bus program. The transits provided 
generally favorable comments on their experience with the equipment.
    Comments or issues fell into the following general categories: (A) 
applicability of the kit; (B) description of the kit; (C) testing 
demonstration and documentation; (D) life cycle cost analysis; (E) 
warranty; (F) durability, and (G) in-use experience. All 
correspondence, comments, and other documentation are located in the 
public docket at the address above.

(A) Applicability

    In the November 6, 1997, Federal Register notice, EPA stated that 
the information provided in DDC's notification applied to 6V92TA DDC 
engines manufactured from January 1979 to December 1989 equipped with 
mechanical unit injectors (MUI) and originally certified to meet 
Federal emission standards.
    In comments dated December 19, 1997, Engelhard stated that DDC has 
failed to provide information demonstrating that this retrofit system 
can be applied safely to all vehicles. Engelhard commented that the 
electrical charging systems of urban buses can vary by make and design 
and asked how can we be sure that this system can be installed in all 
urban buses without an assessment of the charging system and 
information on the stress that the system that the DDC system will 
place on the charging system. Additionally, Engelhard commented that 
the Turbodyne system uses a high speed motor that draws over 300 amps 
for 8 seconds while the bus is accelerating. This will dramatically 
increase the load on the bus' electrical system and will cause 
premature wear of the alternator, battery and electrical systems 
according to Engelhard. The motor that Turbodyne uses to drive the 
compressor can also fail. Engelhard asked if there are any durability 
data or effective life data for this motor, and noted that because 
urban buses stop and start continuously the Turbodyne system will be 
operating during a large portion of the bus operating time.
    According to Engelhard this system is not designed to operate 
continuously and the urban bus application will require it to operate 
much more frequently than it is designed to operate. DDC needs to 
provide information, demonstrating that it is reasonable to expect the 
Turbodyne system will remain operational for 150,000 miles. Engelhard 
commented that it had thoroughly tested the Turbodyne system and found 
air leaks and malfunctioning of the controller system occurred 
frequently. In its comments of December 19, 1997 JMI states that the 
Turbodyne system appears to have two states: on and off. Considering 
the performance cycle of a typical urban bus, this system would be 
turned on every time a bus would pull away from the curb. Since the 
system has a high amperage draw on the bus' electrical system long term 
use could prematurely wear out the battery or starter solemoid. What 
are the long term impacts on the life to the electrical system? Was a 
standard bus battery/starter system used in the test cell? How high is 
the amperage and could this require modifications to the bus' 
electrical system? Could rewiring be required and are there concerns of 
shorts, or fire hazards?
    In response to these comments, DDC states that The TurboPac unit is 
intended to compensate for the inherent lag in the engine turbocharger 
during rapid accelerations from low speed/light load conditions. During 
these periods the TurboPac operates at high speed with a current draw 
of approximately 300 amps. At all other times when the engine is 
operational, the TurboPac runs at low speed in the ``standby'' 
condition with a current draw of about 10 amps. Accelerations 
sufficient to trigger high speed TurboPac operation are expected to 
occur quite frequently in urban bus applications. However, the duration 
of the high speed TurboPac operation is very short. The system limits 
high speed operation to a maximum of eight

[[Page 26801]]

seconds. In most cases the system returns to standby operation in a 
shorter period of time after a preset air box pressure has been 
achieved. DDC logged data on a pilot bus installation at MATS in 
Milwaukee to determine the real-world duty cycle and current draw of 
the TurboPac 2500. The bus was run on a city route through downtown 
Milwaukee in November 1997. The data logger recorded data for 
approximately eight hours in one second intervals. The data analyzed 
encompass a 3 hour time period from just before noon to approximately 
3:00 p.m. This portion was chosen due to the relatively low idle time 
in this sample and the inability of the software to accommodate 
additional data. In the evaluation, when off it was assumed to draw 10 
amps and when it was on it was assumed to draw 300 amps. The data based 
on this evaluation indicates that the TurboPac will be active in the 
high speed mode approximately 10% of the time. The time average draw is 
about 35 amps.
    DDC states that in order to operate on a dedicated electrical 
circuit, unit power is taken directly from the battery, so there are no 
modification necessary to the bus electrical system. A 500 amp fuse is 
installed on the circuit to the controller to protect the system in 
case of a short. DDC began field trials of the retrofit system in July 
1997. To date, eight complete retrofit units have been installed in 
buses and are in regular revenue operation at four major U.S. transit 
services. DDC stated that there have been no problems with the 
electrical systems or batteries on these buses. These units have almost 
40,000 miles of customer service with the high mileage unit having 
accrued over 13,000 miles. In addition, TurboPac systems were installed 
on two buses operating in transit service. One of these units 
experienced an early failure of a hand assembled prototype controller. 
The other bus has operated over 18,000 miles with no failures to the 
TurboPac system.
    DDC states that the in-use evaluation program has not revealed any 
problems with leaks. Consequently, no improvements have been found 
necessary to reduce leaks. Since leaks have not been a problem, DDC has 
not quantified the size of leak that would be sufficient to impair 
performance. With regard to the Engelhard comment concerning system 
leaks, DDC commented that the TurboPac system which Engelhard evaluated 
in early 1996 was a prototype design. In this design, the TurboPac and 
the engine turbocharger compressor were configured in parallel and a 
diverter valve was placed downstream where the two flow paths merged. 
During TurboPac operation, the valve was positioned to permit flow from 
the TurboPac to enter the engine and to block off flow from the 
turbocharger. When the TurboPac was not operational, the valve assumed 
the opposite position. In some early units, the diverter valve did not 
seal adequately and there was backflow through the turbocharger during 
TurboPac operation which resulted in reduced system performance. The 
current system has been completely redesigned to alleviate this 
problem. The TurboPac and engine turbocharger are now in a series 
arrangement. A check valve is placed downstream of the TurboPac and 
allows the engine to draw its intake air either from the TurboPac or 
directly from the engine air cleaner. The check valve has been shown to 
seal adequately and prevent backflow during TurboPac operation. DDC 
noted that the check valve operates in a relatively low pressure zone 
compared to the earlier diverter valve which was exposed to the full 
pressure supplied by the turbocharger.
    Additional batteries or larger capacity alternators have not been 
installed in any of the pilot units and there have been no problems 
with the electrical system. DDC states that because the electrical 
connections for the TurboPac system are independent of the bus 
electrical system, it is not necessary to rewire electrical systems on 
buses. No fires or electrical shorts are expected and none have been 
reported during the pilot installations. DDC does not expect any 
negative impacts on the long term viability and integrity of bus 
electrical systems. During emission testing electrical power for the 
TurboPac was batter supplied.
    DDC has stated that the Delco-Remy 50dn alternator rated at 270 or 
300 amps is the standard in the transit industry and is the only 
alternator that DDC offered with the 6V-92 transit engines. DDC cannot 
state that no other alternator is or could be used on affected transit 
buses, but does state that the use of another type alternator would be 
extremely rare. Delco-Remy provided a statement that the 50dn 
alternator is an approved candidate for use with the DDC kit. It 
further states that the 50dn charging system is designed to operate at 
full capacity and that electrical demand beyond the alternators 
capacity will not adversely affect the alternators performance, 
reliability or durability.
    Based on the above discussion and the responses provided by DDC 
concerning the comments, EPA finds no clear evidence that the DDC 
system is inadequately designed to operate on the urban bus engines to 
which it applies. Further, the in use evaluation program has 
demonstrated the ability to operate without adversely effecting the bus 
electrical systems. Therefore, EPA can find no reason based on the 
above comments not to grant certification of this kit. EPA further 
notes that DDC is required to provide a 100,000 mile defect warranty 
and 150,000 mile emissions performance warranty for the DDC kit and all 
of its components.
    JMI commented that a Turbodyne representative stated publicly at 
APTA's Urban Bus Retrofit/Rebuild Program Panel session in Nashville, 
TN in August 1997, that Transit buses with routes that would require 
the TurboPac to operate more than 30% of the time would not be good 
candidates for using this system to reduce PM levels below 0.1 g/bhp-
hr. JMI noted that this was not referenced in the notice of intent to 
certify and asked if this statement is still accurate? What data is 
available to substantiate DDC/Turbodyne's claim and is industry be 
informed of this comment? In response, Turbodyne provided information 
in letters dated February 23 and February 27, 1998 that during the 
August 1997 APTA Bus Maintenance Workshop in Nashville, a transit 
operator commented that the TurboPac on his routes ``would be on all 
the time.'' The Turbodyne representative replied that he would not 
recommend the TurboPac for applications that exceeded 30% high-speed 
duty cycle. The ceiling of a 30% duty cycle was based on the assumption 
that the bus alternator would not have sufficient excess capacity for 
this type of duty cycle. Excess alternator capacity is a direct 
function of the accessory load and alternator rating. In citing an 
example, a 270-amp system with a total electrical load including the 
accessories of lighting and air conditioning would be 160 amps. The 
excess alternator capacity in this situation would be 110 amps. 
Assuming a 10% duty cycle, this system would have more than sufficient 
excess alternator capacity to meet the average current draw from the 
TurboPac of 35 amps.
    However, if a hypothetical duty cycle of 40% were to exist, the 
TurboPac would require a time-average draw of 140 amps and in this 
scenario the alternator would need to be upgraded before the TurboPac 
would be appropriate. Turbodyne stated, however, that duty cycles that 
exceed 30% are not expected. In practice, Turbodyne stated it would be 
very hard to envision a scenario that would demand 30% high speed 
operation for more than a few minutes. However,

[[Page 26802]]

DDC/Turbodyne will analyze and make recommendations for any situation 
in which the operator believes the vehicle electrical system capacity 
may be in question.

(B) Description of the DDC Kit

    In its comments Engelhard asked how DDC will ensure that future 
rebuilds using this kit will use a new catalyst and not an existing 
catalyst. Will all parts be purchased from DDC? What is the price? Will 
the catalyst be different from the standard ECS 25% catalyst? Will the 
catalyst be labeled as part of the DDC kit? Can DDC ensure catalysts 
are not swapped between buses? In response, DDC states that a converter 
muffler will be part of each rebuild kit. Complete kits will be sold by 
DDC through normal distribution channels. It will not be possible to 
purchase a complete rebuild kit without a converter/muffler assembly 
included. Swapping of catalysts between buses should not be an issue 
since a new catalyst is provided with each kit. The converter muffler 
which will be included in the DDC rebuild kits are supplied by Engine 
Control Systems, LTD (ECS) and are identical to the ECS converter/
mufflers certified to provide a 25% reduction in PM emissions on DDC 
engines on January 6, 1997 as referenced earlier. The catalyst will be 
labeled with an ECS serial and model number. Pricing information on the 
catalyst was not provided as this kit is not being certified within the 
cost ceiling requirements.
    In its comments, JMI asked how many superchargers are actually 
installed on the engine? What are the physical space requirements for 
the supercharger(s)? Will there be adequate space for the 
supercharger(s) on all engines and why are two base engine component 
kits required?
    DDC indicates that one TurboPac Supercharger unit is required for 
each installation. However, the equipment will be supplied in two kits, 
one containing components required for all installations and a second 
which includes those components needed to accommodate the installation 
requirements of the various engine and vehicle configurations. With 
regard to the space issue, DDC indicates that it has performed pilot 
installations on eight different buses which represent five different 
configurations and all have had adequate space to install all kit 
components. According to DDC, these configurations represent over 60% 
of the MUI buses in operation. The remaining designs have been reviewed 
by DDC and found to be similar.
    JMI and Engelhard commented that the DDC instructions for 
installation tell the installer to, ``provide support to the TurboPac 
as required.'' JMI asked what support is required and if the TurboPac 
is not supported as required does this negate the warranty? Engelhard 
asked if this means that additional support of the unit is necessary to 
prevent damage to it or to keep it from contacting other engine 
components. Engelhard also expressed the concern that the directions 
for installation of the Turbodyne TurboPac are insufficient to ensure 
proper installation and operation of the system. Engelhard further 
noted that the instructions require the assembler to ``mount the 
controller in the engine compartment. The location of the controller 
must be in a position which will allow connection of the motor leads 
directly to the TurboPac. The location should provide easy connection 
to the engines starter and in a location which will receive adequate 
air circulation.'' Engelhard asked what is adequate air circulation? 
Engelhard asked if heat would damage the controller and whether the 
unit needs to be shielded?
    In regard to the support concerns, DDC states that the motor and 
compressor weigh 16.5 pounds and will need to be properly supported. 
There are mounting holes on the unit to which the bracket can be 
attached. In the pilot installations, either the transit property or 
the DDC distributor has fabricated a simple bracket to support the 
unit. DDC will provide installation instructions in the assembly and 
installation manual provided with each kit to assist maintenance 
personnel in selecting appropriate support. DDC states that if the 
equipment is not properly installed, damage to the TurboPac due to 
faulty support is not warrantable. DDC states that support failure will 
not damage the engine because the location of the motor and compressor 
is sufficiently away from the engine and does not require contact of 
any kind with the engine components. DDC states that extreme heat would 
damage the controller. Therefore, the controller will be located away 
from exhaust system components, preferably in a area where air can 
circulate around it. It is not recommended that the electronic 
controller be shielded. DDC will provide guidance on locating the 
controller in the installation instructions that are provided with each 
kit. EPA finds that based on the pilot installation experience cited by 
DDC and its review of remaining designs, the guidance provided by DDC 
in its installation instructions should be adequate to properly support 
and locate the kit components. EPA further notes that failure of kit 
components which are installed according to DDC instructions will be 
covered under the warranty provisions.
    Engelhard commented that DDC did not provide a component list for 
the retrofit engine and stated that the list is necessary for 
comparison of the parts used in a standard rebuild to the DDC retrofit 
kit. Engelhard asked if the truck check valve was installed on the test 
engine and whether it will be included in the DDC retrofit kit? In 
response DDC provided information that the build list for the test 
engine corresponds to ``new part kit'' number 23522349 and ``reliabilt 
kit'' number R3518035 included in Parts List Number 3 of the 
notification; TurboPac kits as defined in Parts List Number 5 and 
converter muffler part number 6000-005D as shown in Parts List Number 6 
also in the notification. The check valve is integral to the throttle 
delay assembly and was included in the ``new part kit'' on the test 
engine.
    JMI commented that the DDC application states that ``the throttle 
delay was set for optimum vehicle driveability.'' JMI questioned how 
you adjust for optimum vehicle driveability in the engine test cell? 
Was the throttle delay changed to account for the faster response of 
the engine with the TurboPac? If not, what is the rationale behind this 
decision? In response, DDC stated that the throttle delay is a dashpot 
device which delays the movement of the injector rack to the full fuel 
position. The setting dimension controls the rack position at which 
delays are incurred. A higher numerical setting dimension results in 
the rack being further from the full fuel position and results in more 
delay and poorer driveability. The minimum numeric setting dimension 
positions the rack closest to the full fuel position before any delay 
is incurred. This results in the minimum delay and the best 
driveability. During development testing for the retrofit system, DDC 
determined that the 0.10g/bhp-hr PM level and acceptable engine smoke 
opacity could be achieved with the minimum throttle delay setting of 
0.490 inches. The orifice through which the oil is purged during engine 
acceleration is the same for both truck and bus throttle delays. The 
truck throttle delay has a smaller fill hole which slows the fill rate 
of the oil in the throttle delay body. Bus throttle delays have a 
larger fill hole to provide a more rapid fill. The use of the retrofit 
system has shown that the more rapid fill of the bus throttle delay is 
no longer required to achieve 0.10 g/bhp-hr PM and

[[Page 26803]]

acceptable smoke control. Therefore, a truck type throttle delay was 
specified in order to provide improved driveability.
    JMI commented that in the notification DDC states that; ``Pursuant 
to 40 CFR Section 85.1406(e), * * * does not alter or render 
inoperative any feature of the on-board diagnostic system incorporated 
by the engine manufacturer.'' JMI asked what type of diagnostic systems 
are incorporated on MUI engines? In response, DDC states that MUI 
engines are not equipped with a computer which can store problem codes 
that can be used later by a service technician to diagnose an engine 
problem. The reference statement was provided by DDC as part of the 
standard format for notifications of intent to certify under the urban 
bus retrofit/rebuild program.

(c) Testing

    JMI commented that the notification started that the rebuilt engine 
for the test program was originally a 1984 engine but it doesn't state 
that the engine was rebuilt to a 1984 configuration prior to testing. 
What was the configuration of the baseline engine and is it consistent 
with the claims made by DDC? Engelhard commented that DDC has not 
included a baseline test for comparison with the proposed retrofit kit 
and that this data is necessary to verify that the equipment being 
installed on the engine does not affect engine performance or fuel 
economy.
    EPA notes that DDC did not perform baseline testing for this 
notification. Under the urban bus retrofit/rebuild program baseline 
testing is required when certification is requested within specified 
life cycle cost limitations. In such cases, baseline testing is needed 
to demonstrate equipment impact on fuel economy and associated life 
cycle costs. EPA does not require baseline testing when demonstrating 
compliance with the 0.10 g/bhp-hr PM standard when certification with 
life cycle cost requirements is not requested and if all applicable 
engines are to be converted to the test engine configuration during 
retrofit/rebuild. In view of the fact that this certification is not 
being made within life cycle cost limits, and all converted engines 
will be retrofit to the test engine configuration, baseline testing is 
not required for this certification.
    Prior to performance of the emissions test, the test engine was 
rebuilt using the DDC kit. DDC stated that the test engine was in a 
post-rebuild configuration which is not related to a particular model 
year. However, DDC noted that the test engine was mechanically similar 
to a 1989 configuration.
    JMI commented that DDC stated in the notification that the 277 hp 
rating was chosen because, ``it represents the engine injector 
combination on which the candidate equipment will be used.'' JMI 
commented that this statement is understandable if DDC is certifying 
only 277 hp engine kits. However, the DDC application also claims 0.10 
g/bhp-hr PM levels for 253 hp and 294 hp engine kits. JMI asked what 
FTP test date is available to demonstrate that this technology is 
effective on 253 hp and 294 hp engine. JMI stated that the EPA should 
require DDC to demonstrate that they can attain 0.10 g/bhp-hr level for 
these two horsepower ratings before including them in DDC's 
application.
    Additionally, Engelhard commented that DDC has not tested the worst 
case engine for its system. The Turbodyne system is designed to force 
additional air into the intake before the standard turbocharger can 
spool up. According to Engelhard, it is the amount of air supplied 
during aceleration that allows better combustion which reduces the 
particulate emissions during acceleration. The amount of air supplied 
is critical for obtaining PM reduction. The emissions data supplied by 
DDC is for a 277 hp engine. Engelhard states that to meet the 0.10 g/
bhp-hr level, the Turbodyne system will have to supply more air for a 
294 hp engine. However, DDC has provided no justification or data 
demonstrating that the device is large enough to accommodate the air 
flow requirements of the 294 hp engine. This requirement is supported 
by the fact that DDC uses a different turbo with a higher A/R ratio for 
the 294 hp engine than the 277 hp engine.
    DDC stated that it selected the 277 hp engine rating for 
certification testing because this is the rating most commonly used in 
transit bus operations. DDC agrees that the 294 hp engine will require 
more airflow than an engine rated at 277 hp when both engines are 
operating at their respective full rated power. DDC also points out 
that the TurboPac is not intended to deliver the full airflow 
requirements of the engine. The purpose of the TurboPac is to provide 
additional air during engine accelerations to compensate for the lag of 
the engine turbocharger, and its air supply performance is the same for 
all engines regardless of power rating. DDC states that an engine at 
the 294 hp rating is capable of injecting more fuel than an engine at 
the 277 hp rating, but the difference in fueling is small. The 294 hp 
rating has a peak torque of 875 lb-ft at 1200 rpm while the 277 hp 
rating has a peak torque of 880lb-ft at 1000 rpm. At 1200 rpm, full 
load, under steady state conditions, the 294 hp rating delivers 71.0 
lb/hr of fuel vs. 68.5 lb/hr for the 277 hp engine. DDC notes that this 
is only a 3.6% difference. DDC has not measured fueling differences for 
the two ratings during rapid accelerations, but because the throttle 
delay limits fueling to some fraction of the full rack fueling, the 
fueling difference during acceleration would be somewhat less than the 
steady state difference. Since the fueling difference is small, DDC 
believes the TurboPac will provide sufficient supplementary air to 
provide adequate particulate control with the 294 hp engine.
    EPA's urban bus certification requirements for heavy-duty urban bus 
diesel engines, 40 CFR 85.1406 (a)(2)(i) states ``The test engine used 
must represent the `worst case' with respect to particulate emissions 
of all those engine configurations for which the retrofit/rebuild 
equipment is being certified. The worst case engine configuration shall 
be the engine configuration having the highest engine-out particulate 
matter emission levels, when properly maintained and used, prior to 
installation of the retrofit/rebuild equipment.'' Based on available 
information, it is not clear whether an engine rated at 253 hp, 277 hp, 
or 294 hp would have significantly different exhaust emissions or, 
which would represent the worst case for this certification decision.
    EPA believes that a comparison with the criteria for selecting test 
engines under EPA's new engine certification program is relevant. EPA's 
new engine certification requirements for heavy-duty diesel engines, 40 
CFR Sec. 86.090-24 (b)(3)(ii) for test engine selection state ``* * * 
Within each combination, the engine that features the highest fuel feed 
per stroke, primarily at the speed of maximum rated torque and 
secondarily at rated speed, will usually be selected'' for a test 
engine. In a facsimile dated March 7, 1998, DDC provided information on 
the fuel feed rate for each hp at maximum rated torque. That 
information shows that the fuel feed per stroke for the 277 hp engine 
clearly exceeds the 253 hp at maximum rated torque (88.8 mm/stroke vs. 
77.4 mm/stroke). With regard to the 294 hp engine, DDC has provided 
information that the fuel feed per stroke for the 277 hp engine is 
virtually identical to the fuel feed per stroke of the 294 hp engine at 
maximum rated torque (88.8 vs. 88.9 mm/stroke). While a strict 
comparison of this data indicates that the 277 hp engine does not meet 
the ``highest fuel

[[Page 26804]]

feed per stroke'' criteria as stated, it is within one-tenth of one 
percent of the 294 hp rating with regard to this measurement. DDC's 
March 27, 1998 submission has been placed in the docket at the above 
address.
    In conjunction with the discussion above and the following reasons, 
EPA believes that the 6V92TA engine equipped with the DDC kit rated at 
277hp, is acceptable for compliance at the 253, 277 and 294 hp ratings. 
First, the 6V92TA MUI test engine is clearly the engine model for which 
DDC is claiming applicability of the DDC kit. Further, the hp rating of 
the certification is the most popular power rating. It is therefore the 
most representative power rating. Second, it is consistent with the use 
of a 277hp test engine by JMI for certification applicable to various 
hp ratings applicable to 6V92TA model engines (see 62 FR 60079; 
November 6, 1997). In EPA's approval of this JMI certification kit, EPA 
allowed the certification test engine at the 277 hp rating to represent 
additional hp ratings which were certified. No additional information 
was presented by JMI or Engelhard in their respective comments relative 
to different emission levels from the various ratings. Lacking such 
information EPA can find no reason to change from the decision made in 
the JMI certification to allow the 277 hp test engine to represent the 
additional ratings. Additionally, it is not clear that an engine of the 
DDC rated 253 hp or 294 hp would have significantly different exhaust 
emissions from the certified test engine. Because of the above noted 
reasons, and consistent with EPA's decision in that JMI certification, 
EPA finds that the 277 hp rating is acceptable to represent the 253 hp 
and the 294 hp ratings in this certification. EPA retains the authority 
to conduct in-use testing of any certified equipment for compliance 
with the 150,000 mile performance warranty on all certified equipment.
    JMI commented that the test data states that the muffler was 
installed 6 feet from the turbocharger exit. JMI asked if this is the 
way it will be installed in the buses. JMI noted that the converter 
muffler is a direct bolt on replacement for the original muffler. With 
the extreme variation in diameter from muffler to muffler, how many 
different size catalyst elements are used? If more than one, which one 
was used during the FTP test? If only one, the EPA should require DDC 
to provide assurances that the catalyst was sized to achieve 0.1 g/bhp-
hr PM for the complete range of 6V92TA MUI engines form 1979 to 1989.
    DDC stated that the converter muffler was tested at a location of 
six feet from the turbocharger outlet. The installation on a particular 
urban bus will vary based on the original muffler location. DDC tested 
at this distance as most urban bus mufflers are installed within this 
distance from the turbocharger and chose this location to represent a 
worst case in terms of exhaust temperature. EPA accepts the placement 
of the converter at six feet from the turbocharger in this instance and 
notes that EPA has accepted this distance in previous certification 
approvals.
    DDC stated that parts list number six in the notification provides 
a listing of the different converter/muffler configurations that will 
be used. The particular converter/muffler configuration used to 
generate the emission test results in the notification was a 12 inch by 
23 inch oval cross section design, 22 inches in length. This unit has 
the minimum catalyst volume of the different converter/muffler 
configurations that will be used according to DDC and corresponds to 
part number 6000-005D of that list.
    Engelhard asked how the backpressure was set for emissions testing. 
DDC testing was performed at Southwest Research Institute in San 
Antonio, Texas. With a standard muffler installed in the test cell 
exhaust system, the damper was closed (with the test engine at rated 
speed) to adjust the backpressure to 80% of the specified maximum, or 2 
inches of mercury. The standard muffler was then removed, and the 
catalyst was installed in its place. Certification testing was 
conducted without changing the position of the throttling valve. The 
resulting backpressure was 2.7 inches of mercury with the catalyst 
installed. Engelhard asked where did the original muffler come from and 
is it a bus muffler? The muffler was provided by the testing facility 
and was selected to represent an urban bus muffler.

(D) Life Cycle Cost Analysis

    Engelhard commented that DDC has not provided a life cycle cost 
calculation for this retrofit equipment. Engelhard noted that this is 
extremely important due to the complexity of the installation required 
for the Turbodyne system, the potentially expensive maintenance of the 
system, the detrimental effect of the huge electrical demand of the 
Turbodyne system on the buses charging system, and the increased fuel 
consumption of the Turbodyne system. Engelhard commented that this 
information is needed so bus companies can make a valid assessment of 
this technology's cost effectiveness. DDC's application also did not 
include prices or installation costs for any of the retrofit kits. JMI 
also commented on the cost of the DDC/Turbodyne kit. It asked about the 
labor costs to install the DDC/Turbodyne system because the addition of 
a supercharger is over and above what is done during a standard 
rebuild. Are there any periodic maintenance requirements that would 
increase the cost of the system? What is the impact of the DDC/
Turbodyne technology on fuel consumption? Should a fuel penalty be 
assessed?
    As stated earlier, DDC has not provided life cycle cost information 
in conjunction with this notification. Such a cost analysis is 
necessary for certification of equipment that is meant to trigger a 
program emissions standard. Certification of Engelhard Corporation's 
ETX<SUP>TM</SUP> kit triggered the 0.10 g/bhp-hr standard for 6V92TA 
MUI engines, and made available kits rated at 253, 277, and 294 hp. The 
DDC certification does not include a cost analysis, and one is not 
necessary for this certification. DDC states that engines equipped with 
the kit will have no additional maintenance or service requirements and 
the system will not have a detrimental impact on the electrical system 
as discussed earlier. Based on the field installations to date, DDC 
estimates that the installation of the TurboPac unit will average an 
additional eight hours of labor beyond the labor associated with a 
standard rebuild. However, this figure could vary depending on the 
specific installation requirements. No claims have been made by DDC 
with regard to the impact of this system on fuel economy and the impact 
of this system on fuel economy is undetermined. No specific information 
on fuel economy impact was provided in the comments. EPA notes that it 
is not appropriate to assess a fuel economy penalty in a certification 
that does not contain life cycle cost information. With regard to fuel 
consumption, the brake specific fuel consumption (BSFC) measured during 
emission testing of the DDC kit was 0.464 lb/bhp-hr. In testing 
conducted for the three notifications for 0.1 g/bhp-hr PM certification 
for 6V92TA MUI engine models that EPA has received to date, the BSFC 
measured during emission testing after the installation of the 
retrofit/rebuild kits has been between 0.438 and 0.471 lb/bhp-hr.
    JMI asked if there are any components or ancillary parts that are 
required in order to install the DDC/Turbodyne system that are not 
included on any of the parts lists included with DDC's application? If 
so, what are the additional costs associated with these

[[Page 26805]]

parts? In response, DDC states that the parts list in the application 
does not include the electrical wire (16 AWG and 00 cable), and some 
nuts and bolts. DDC states that it believes these are standard items 
commonly available in bus repair facilities. Total cost for all of 
these parts is estimated by DDC to be between $20 and $40, depending on 
the length of the 00 cable. No additional batteries or other changes 
are required to the battery charging system. No rewiring of the bus 
electrical system is needed according to DDC.

(E) Warranty

    Engelhard commented that DDC does not provide any coverage for 
damage resulting to other engine components, such as the charging 
system, due to the installation of its retrofit kit. In response, DDC 
notes that field evaluations have not resulted in any failures to bus 
charging or electrical systems. Neither DDC nor Delco-Remy anticipate 
that use of the TurboPac system will increase failure rates of the 
vehicle charging and electrical systems. Standard warranty coverages, 
if not expired, will remain in effect for any failures which may occur 
in these systems. DDC will not provide additional warranty coverage for 
these systems. Based on the review of comments and the in-use pilots, 
EPA is not award of any damage to other components as a result of the 
installation of this equipment and does not see reason not to approve 
this certification. If significant in-use problems were to develop, EPA 
can take action and, ultimately, has authority to decertify equipment.

(F) Durability

    JMI commented that DDC stated in its notification; ``The cylinder 
kit components were modified to improve durability.'' JMI expressed 
concerns that changes to any parts of the cylinder kits could result in 
increased soot formation in the oil or increased oil consumption. JMI 
further questioned what the modifications were, how will they be made, 
who will make them, how DDC will control uniformity and quality, 
whether the change was made for all 92 series engines or just the 
engines with the kit and whether the parts will be made available on a 
nationwide basis. Engelhard commented that though durability data is 
not a requirement of the Urban Bus regulation, the EPA has required 
verification of durability and data supporting the claim that the 
system will last 150,000 miles.
    In response DDC stated that the primary change in the cylinder kit 
is the elimination of a ``J-relief'' groove. The J-relief was a 
machining process to the lower side of the bottom compression ring 
groove which was designed to relieve any pressure build-up between the 
upper and lower compression rights. The change to the piston eliminates 
the machining operation. DDC states that this change has no affect on 
the combustion process, and will have no affect on generation of soot 
during the combustion process. According to DDC the change was made 
strictly to improve the durability of the lower compression ring. The 
changes have been incorporated in the cylinder kits used to service all 
DDC series 92 engines, whether used to service truck, bus, or nonroad 
engines. The new piston domes are also used on production engines. 
Therefore, the parts are subject to the same quality control as any 
other DDC production or service part. The new kits are available 
worldwide through DDC's distributor network.
    EPA is concerned, in general, with equipment durability, and 
believes that certifiers will want to evaluate the durability of their 
equipment in order to minimize their liability resulting from the 
emissions defect and performance warranties. However, program 
regulations do not require a durability demonstration. EPA believes 
that DDC's explanation does not indicate a durability concern with the 
equipment certified in today's notice, and therefore, does not provide 
sufficient basis to deny certification on these grounds. EPA has the 
authority to conduct in-use testing of certified equipment to determine 
compliance with the requirements of the program. In addition, equipment 
certifiers must provide a 100,000 mile defect warranty and a 150,000 
miles emissions performance warranty on all certified equipment

(G) In-Use Experience

    The Washington Metropolitan Area Transit Authority (WMATA), the 
Maryland Department of Transportation Mass Transit Administration 
(MTA), and the Milwaukee County Transit System (MCTS) provided 
favorable comments on the DDC system. WMATA noted that one DDC kit was 
installed on September 17, 1997 and that WMATA has not encountered any 
installation or servicing problems with the engine and there have been 
no failures. The MTA commented that it has installed the DDC kit and it 
has performed ``flawlessly.'' The MCTS commented that it has installed 
five DDC kits. The first kit was installed in September 1997. To date, 
MCTS has not experienced ``any'' electrical component problems on the 
buses. By electrical problems, MCTS stated it meant any alternator, 
regulator, battery, or wiring problems. MCTS commented that it 
experienced ``one'' TurboPac electrical turbo motor failure early in 
the test process. MCTS commented that the DDC kit is reliable but that 
it was too early in the process to determine if there are any fuel or 
power increases.

IV. Certification

    The Agency has reviewed the notification of intent to certify and 
other information provided by DDC, along with comments received from 
interested parties, and finds that the DDC kit described above:
    (1) Complies with the particulate matter exhaust emissions standard 
of 0.10 g/bhp-hr, 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).
    Therefore, today's Federal Register notice announces certification 
of the above-described DDC kit for use in the urban bus retrofit/
rebuild program as discussed below in section V.

V. Transit Operator Responsibilities

    Today's Federal Register notice announces certification of the 
above-described DDC kit, when properly applied, as meeting the 0.10 g/
bhp-hr particulate matter standard of the Urban Bus Retrofit/Rebuild 
Program.
    In a Federal Register notice dated March 14, 1997 (62 FR 12166), 
EPA announced certification of a retrofit/rebuild kit produced by the 
Engelhard Corporation (the ETX<SUP>TM </SUP>kit). That certification 
means that urban bus operators using compliance program 1 must use 
equipment certified to the 0.10 g/bhp-hr standard when rebuilding or 
replacing applicable 1979 through 1989 model year DDC 6V92TA MUI model 
engines after September 14, 1997. The certified DDC equipment described 
in today's notice may be used by operators in compliance with the 0.10 
g/bhp-hr standard. Operators using compliance program 2 having 
applicable engines may use the certified DDC kit and claim the 
certification PM level from Table B above, when calculating their Fleet 
Level Attained (FLA). Under program 2, an operator must use sufficient 
certified equipment so that its actual fleet emission level complies 
with the target level for its fleet.

[[Page 26806]]

    As mentioned above, certification of the Engelhard 
ETX<SUP>TM </SUP>kit triggered the 0.10 g/bhp-hr standard for 
applicable 1979-1989 6V92TA MUI engines. That kit provides three power 
ratings: 253, 277, and 294 horsepower. DDC will offer the DDC kit in 
these three power ratings as well: 253, 277, and 294hp.
    Engines of urban buses certified to meet California emissions 
standards are not applicable to the DDC kit discussed in today's 
Federal Register notice. Additionally, the 0.10 g/bhp-hr PM standard is 
not triggered for engines certified to meet California emission 
standards. Operators of such urban buses, who choose to comply with 
program 1, are not required to use equipment certified to the 0.10 g/
bhp-hr PM standard until the standard has been triggered for such 
engines. Operators of urban buses having engines certified to meet 
California emission standards, and who choose to comply with program 2, 
may not use the DDC kit described in today's notice to meet program 
requirements.
    As stated in the program regulations (40 CFR 85.1401 through 
85.1415), operators must, beginning January 1, 1995, maintain records 
for each engine in their fleet to demonstrate that they are in 
compliance with the requirements of the Urban Bus Retrofit/Rebuild 
Program. These records include purchase records, receipts, and part 
numbers for the parts and components used in the rebuilding or urban 
bus engines.

    Dated: May 5, 1998.
Richard D. Wilson,
Acting Assistant Administrator for Air and Radiation.
[FR Doc. 98-12850 Filed 5-13-98; 8:45 am]
BILLING CODE 6560-50-M