Interpretation ID: aiam4404
Director of Engineering
Thomas Built Buses L.P.
P.O. Box 2450
High Point
NC 27261;
Dear Mr. Mathieson: This is in reply to your letter of April 27, 1987, asking for clarification of my letter of March 20.; In that letter I answered your question as to whether the results o frontal barrier impact tests that occurred at 30.4 mph with a vehicle that exceeded the test weight limits would constitute either a noncompliance with Standard No. 301 or a safety related defect. Because the test was not conducted in accordance with Standard No. 301's conditions I replied that this would not be a noncompliance, and further, that those results 'do not constitute a safety related defect regardless of the use of the vehicle.' This statement appears unclear to you.; By my earlier statement I intended to explain that we do not use safety standard's compliance test results (particulary if the test was not conducted in accordance with the prescribed procedures) as the sole basis for a determination of a safety-related defect in the same aspect of performance governed by that standard. For example, having determined through rulemaking that a particular level of vehicle performance is expected in a 30 mph crash test, it would be inappropriate to use the results from an otherwise identical crash test conducted at 35 mph to form the sole basis for a determination of a safety-related defect in the tested vehicles. To do so would constitute, in effect, rulemaking to raise the impact speed in the standard to 35 mph. We completely agree, however, with your statement that 'there can be safety- related defects that are not addressed by the standards.' We also agree that the manufacturer has the responsibility to address safety defects that become apparent to him through test data or otherwise.; With this background, we will turn to your question. You have now pose a hypothetical in which your tests indicate that a fully-loaded school bus may encounter a severe leakage exceeding 4.1 ounces of fuel per minute in a head-on impact of 30 m.p.h. This may be evidence that could lead you to believe that there would be a significant number of failures if a school bus, in its normal operation with full complement of students, encounters a head-on collision at what appears to be a reasonable operating speed. This combination of factors might appear to pose an unreasonable risk to safety and afford the basis for the determination that a safety related defect exists.; Sincerely, Erika Z. Jones, Chief Counsel