Interpretation ID: aiam3890

Dear Mr. Confidential: This is in reply to your letter of August 30, 1984, (not received unti October 17, 1984) with respect to questions of compliance of lighting and bumper requirements on a vehicle equipped with a variable height control system.; Standard No. 108 requires that the center of a headlamp lens be no less than 22 inches from the road surface. You stated that this minimum might not be met with respect to certain headlamp configurations when the ignition is off, and the hydraulic pressure in the height control system relaxes, a period of approximately three hours. You believe that compliance with the mounting height requirement should be judged 'with the ignition switch in only the 'on' position,' the apparent point at which the height control system begins to operate.; We believe that the minimum height requirement should be met for an lamp at any time in which it is operated for its intended purpose. Since vehicles at rest do not require use of headlamps, the minimum height would be measured at the point after the ignition is on and when the car begins to travel (your letter implies that the time lag between turning on the ignition and restoration of a complying mounting height is a matter of seconds). On the other hand, the hazard warning signal lamps are frequently operated when the vehicle is stopped, and therefore the minimum mounting height of turn signal lamps, through which they operate, must be met with the ignition off, even if the system requires three hours to deplete itself and lower the vehicle to its minimum height.; We also call to your attention paragraph S4.1.3 which forbids th installation of motor vehicle equipment which impairs the effectiveness of lighting equipment required by the standard, and ask that you consider whether a height control system would change vehicle height, pitch, roll, etc., in response to some external or internal condition, in a manner which would affect the performance of headlamps and other lighting equipment.; You have also asked, in essence, which conditions of operation of th system are appropriate for the pendulum and barrier impact tests of the bumper standard, 49 CFR Part 581. Under Sec. 581.5(c), the suspension system is to remain in adjustment and operate in the normal manner, under Sec. 581.6(c) the engine is operating at idling speed. In our opinion, the vehicle is required to meet the pendulum test of Part 581 in any vehicle use scenario in which the system operates, and the barrier test of Part 581 when the engine is idling.; Finally, you requested confidentiality for all information submitte which pertains to the variable height control system. After carefully reviewing the documents, I have determined that your request should be granted. The release of these documents could cause substantial injury to the competitive position of your company. Therefore, I am withholding from the public your letter which contains a detailed description of the variable height control system currently under consideration. I am also deleting all references to the company name. I will instruct all agency personnel having access to this information to accord it confidential treatment.; I hope that this answers your questions. Sincerely, Frank Berndt, Chief Counsel