Interpretation ID: nht73-4.24

DATE: 06/01/73

FROM: AUTHOR UNAVAILABLE; J. E. Wilson; NHTSA

TO: General Motors Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of May 11, 1973, asking for confirmation of your interpretation of paragraph S7.9 of Standard No. 105a in terms of General Motors' air vacuum power brake.

Your interpretation is correct. Your system with its "two separate and independent energy sources in the power head . . . is equivalent to two entirely duplicate systems", and disconnection of one source at a time would be the correct test procedure under S7.9, provided the requirements of S5.1.3 are satisfactorily met under both conditions.