Interpretation ID: nht94-4.69

TYPE: INTERPRETATION-NHTSA

DATE: October 28, 1994

FROM: Donald T. Hoy -- Senior Marketing Manager, Clean Air Partners

TO: Philip R. Recht -- Office of Chief Counsel

ATTACHMT: ATTACHED TO 2/27/95 LETTER FROM PHILIP R. RECHT TO DONALD T. HOY (REDBOOK 2; PART 303)

TEXT: The purpose of this letter is to obtain written confirmation on the issue of converting a school bus to run on a blended fuel of compressed natural gas (CNG) or liquefied natural gas (LNG) and diesel. During my conversation this morning with Mr. John Wo mack, I outlined our intention to convert school busses to run on a blended fuel of natural gas and diesel in Seattle, Washington. We fully intend to market this product in other states as well.

Basically, the Clean Air Partners, Inc. (CAP) CARB certified conversion system is designed to bolt on the original equipment manufacturer (OEM) diesel engine. The diesel fuel system remains intact and operates as designed during the duty cycle of the eng ine. Our conversion, during the dual fuel cycle, simply reduces the flow of diesel fuel to the engine and substitutes natural gas in its' place. Should your on board supply of natural gas be depleated, the system automatically reverts back to 100% diese l with no interruption in driveability.

With this brief description of our conversion system in mind, I would like to ask a few questions:

1. Are there any Federal Regulations preventing the conversation of a school bus from diesel to a "dual fuel" school bus?

2. With regard to vehicle certification, is there any significance as to when the conversion is installed on any school bus?