[Federal Register: May 25, 1999 (Volume 64, Number 100)] [Notices] [Page 28242-28243] From the Federal Register Online via GPO Access [wais.access.gpo.gov] [DOCID:fr25my99-132] ----------------------------------------------------------------------- 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]] ---------------------------------------------------------------------------------------------------------------- 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