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Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Rules and Regulations
1066.265 Acceleration and deceleration verification.

d
1 Calculate the force setting, F, using the following equation:

t = coastdown time for each speed interval and inertia setting, accurate to at least 0.01 s.

Example:
I = 2000 lbm = 62.16 lbfs2/ft vinit = 25 mi/hr = 36.66 ft/s vfinal = 15 mi/hr = 22.0 ft/s t = 5.00 s
F= 62.16-36.66-22.0
5.00

Eq. 1066.265-4
Where:
Ib = the dynamometer manufacturers stated base inertia, in lbfs2/ft.
a = nominal acceleration rate, in ft/s2.

Example:
Ib = 2967 lbm = 92.217 lbfs2/ft a = 1 mi/hr/s = 1.4667 ft/s2
F = 92.2171.4667
F = 135.25 lbf

382. Amend 1066.270 by revising paragraphs c4 and d2 to read as follows:
1066.270 Unloaded coastdown verification.

c
4 Determine the mean coastdown force, F, for each speed and inertia setting for each of the coastdowns performed using the following equation:

F= I

v.mit -vfmal
t Eq. 1066.270-1

Where:
F = the mean force measured during the coastdown for each speed interval and inertia setting, expressed in lbf and rounded to four significant figures.
I = the dynamometers inertia setting, in lbfs2/ft.
vinit = the speed at the start of the coastdown interval, expressed in ft/s to at least four significant figures.
vfinal = the speed at the end of the coastdown interval, expressed in ft/s to at least four significant figures.

F = 182.3 lbf

d
2 For vehicles above 20,000 pounds GVWR, the maximum allowable error, Ferrormax, for all speed intervals and inertia settings is 1.0% or the value determined from Eq. 1066.2703
substituting 8.8 lbf for 2.2 lbf in the numerator, whichever is greater.

383. Amend 1066.275 by revising paragraphs b and d to read as follows:
1066.275 Daily dynamometer readiness verification.

b Scope and frequency. Perform this verification upon initial installation, within 1 day before testing, and after major maintenance. You may run this within 7 days before testing if you accumulate data to support a less frequent verification interval.

d Performance evaluation. The coastdown force error determined in paragraph c of this section may not exceed the following:
1 For vehicles at or below 20,000
pounds GVWR, 1.0% or the value determined from Eq. 1066.2703, whichever is greater.
2 For vehicles above 20,000 pounds GVWR, 1.0% or the value determined from Eq. 1066.2703 substituting 8.8 lbf for 2.2 lbf, whichever is greater.

384. Revise 1066.405 to read as follows:

1066.405 Vehicle preparation, preconditioning, and maintenance.

a Prepare the vehicle for testing including measurement of evaporative and refueling emissions if appropriate, as described in the standard-setting part.
b If you inspect a vehicle, keep a record of the inspection and update your application for certification to document any changes that result. You may use any kind of equipment, instrument, or tool that is available at dealerships and other service outlets to identify malfunctioning components or perform maintenance.
c You may repair defective parts from a test vehicle if they are unrelated to emission control. You must ask us to approve repairs that might affect the vehicles emission controls. If we determine that a part failure, system malfunction, or associated repair makes the vehicles emission controls unrepresentative of production engines, you may not use it as an emission-data vehicle. Also, if the engine installed in the test vehicle has a major mechanical failure that requires you to take the vehicle apart, you may no longer use the vehicle as an emission-data vehicle for exhaust measurements.
385. Amend 1066.420 by revising paragraph d to read as follows:
1066.420

Test preparation.

d Control test cell ambient air humidity as follows:
1 For vehicles at or below 14,000
pounds GVWR, follow the humidity requirements in Table 1 of this section, unless the standard-setting part specifies otherwise. When complying with humidity requirements in Table 1, where no tolerance is specified, use good engineering judgment to maintain the humidity level near the specified value within the limitations of your test facility.
2 For vehicles above 14,000 pounds GVWR, you may test vehicles at any humidity.
3 Table 1 follows:

AC17
FTP a and LA92
HFET
SC03
US06
a FTP

69
50
50
100
50

Tolerance grains H2O per pound dry air 5 average, 10 instantaneous.

ER29JN21.268

lotter on DSK11XQN23PROD with RULES2

Test cycle
5 average.

humidity requirement does not apply for cold 7C, intermediate 10C, and hot 35C temperature testing.

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ER29JN21.267

Humidity requirement grains H2O
per pound dry air
ER29JN21.269

TABLE 1 OF 1066.420TEST CELL HUMIDITY REQUIREMENTS