[Federal Register Volume 64, Number 100 (Tuesday, May 25, 1999)]
[Notices]
[Pages 28242-28243]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-13160]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration
[Docket No. NHTSA-99-5681]


American Transportation Corp., Receipt of Application for 
Decision of Inconsequential Noncompliance

    American Transportation Corporation (AmTran) has determined certain 
air brake systems on AmTran buses were built with air tank volumes that 
are not in full compliance with Federal Motor Vehicle Safety Standard 
(FMVSS) No. 121, ``Air brake systems,'' and has filed an appropriate 
report pursuant to 49 CFR part 573, ``Defect and Noncompliance 
Reports.'' AmTran has also applied to be exempted from the notification 
and remedy requirements of 49 U.S.C. Chapter 301--``Motor Vehicle 
Safety'' on the basis that the noncompliance is inconsequential to 
motor vehicle safety.
    This notice of receipt of an application is published under 49 
U.S.C. 30118 and 30120 and does not represent any agency decision or 
other exercise of judgment concerning the merits of the application.
    FMVSS No. 121 establishes the performance and equipment 
requirements for the braking systems on vehicles equipped with air 
brake systems. Paragraph S5.1.2.1. of FMVSS No. 121 states that the 
combined volume of all service reservoirs and supply reservoirs shall 
be at least 12 times the combined volume of all service brake chambers.
    From October 27, 1995 through November 5, 1998, AmTran produced 122 
units with an air reservoir combined volume of 3,630 cubic inches or 
11.6 times the combined volume of all service brake chambers. AmTran 
supports its application for inconsequential noncompliance by stating 
the following:

    ``The combined air reservoir capacity of 3,630 cubic inches is 
only 114 cubic inches under the required volume of the system to 
meet FMVSS [No.] 121 S5.1.2.1. The 12 times formula was established 
at a time when automatic slack adjusters were not common in the 
industry. Today, they are standard [and provide] improved brake 
adjustment. Properly adjusted brakes require less air volume for 
application. A driver of a unit with a volume shortage of 114 cubic 
inches more than likely would never experience any difference in 
braking capability. [A] previous test conducted by NHTSA indicated 
that the 12 times volume provided sufficient reserve volume to stop 
an air-braked vehicle equipped with antilock brakes even under the 
worst-case conditions. The table below adds further credibility when 
theoretical calculations supporting our statement that [a] driver 
would not experience any significant effect on stopping distance due 
to air pressure differentials. The calculations were based on SAE 
J1911, a test procedure for air reservoir capacity. SAE J1609 gives 
the criteria that after the eighth brake application, the pressure 
in the air reservoir shall not be less than 45 psi. The calculations 
also assume no split between the wet, secondary and primary for 
simplicity. [Note: For the Hard Stop--full application in traction 
limited condition] Pressure in the system assumes worst case of full 
on, full off eight times. Somewhat simulates a crude antilock 
system.''

[[Page 28243]]



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                                                                                     Pressure in system (psi)
                                                                                 -------------------------------
                                                                      Initial        Compliant     Non-compliant
                          Type of stop                               reservoir       reservoir       reservoir
                                                                  pressure (psi)   volume (3,744   volume (3,630
                                                                                      in \3\)         in \3\)
----------------------------------------------------------------------------------------------------------------
Normal Application (30 psi or less).............................             120           117.5           117.4
                                                                             110           107.5           107.4
Hard Stop (Full application in non-traction limited condition)..             120           110.8           110.5
                                                                             110           101.5           101.3
Hard Stop (Full application in traction limited condition)......             120            63.3            62.0
                                                                             110            58.0            56.9
----------------------------------------------------------------------------------------------------------------

    Interested persons are invited to submit written data, views, and 
arguments on the application described above. Comments should refer to 
the docket number and be submitted to: U.S. Department of 
Transportation, Docket Management, Room PL-401, 400 Seventh Street, 
SW., Washington, DC, 20590. It is requested that two copies be 
submitted.
    All comments received before the close of business on the closing 
date indicated below will be considered. The application and supporting 
materials, and all comments received after the closing date, will also 
be filed and will be considered to the extent possible. When the 
application is granted or denied, the notice will be published in the 
Federal Register pursuant to the authority indicated below.
    Comment closing date: June 24, 1999.

(49 U.S.C. 30118, 30120; delegations of authority at 49 CFR 1.50 and 
501.8)

    Issued on: May 19, 1999.
L. Robert Shelton,
Associate Administrator for Safety Performance Standards.
[FR Doc. 99-13160 Filed 5-24-99; 8:45 am]
BILLING CODE 4910-59-P