Interpretation ID: nht92-9.20

DATE: February 7, 1992

FROM: Charles Danis, P.Eng. -- Les Entreprises Track Test Inc.

TO: Paul Jackson Rice -- Chief Counsel, NHTSA

TITLE: Subject: Interpretation of FMVSS 121 - S5.3.3 (as per our phone call with your Mr. Marvin Shaw, on February 6th 1992)

ATTACHMT: Attached to letter dated 4/3/92 from Paul J. Rice to Charles Danis (A39; Std. 121)

TEXT:

We recently performed a compliance FMVSS 121 test on an articulated bus made by MCI Greyhound Canada. For the middle axle of this articulated bus, MCI is using different air pressures than those specified in paragraph S5.3.3. of FMVSS 121 (for reasons of safety).

Based on the attached interpretation dated July 23rd 1976 from your Mr. Frank A. Berndt, MCI is using 40 psi as initial service reservoir system air pressure and 28 psi as brake. chamber pressure (at .45 sec. max.). In the case of release, MCI is using 40 psi.

We would appreciate very much if you could confirm by return that this attached interpretation is still valid.