Interpretation ID: nht88-2.8

TYPE: INTERPRETATION-NHTSA

DATE: 04/27/88

FROM: L.T. MITCHELL -- THOMAS BUILT BUSES

TO: ERIKA Z. JONES -- CHIEF COUNSEL NATIONAL HIGHWAY TRAFFIC

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 08/03/89 EST; FROM STEPHEN P. WOOD -- NHTSA TO L.T. MITCHELL -- THOMAS BUILT BUSES INC; REDBOOK A33; STANDARD 217; LETTER DATED 02/24/89 FROM DAN TREXLER -- THOMAS BUILT BUSES INC; TO JOAN TILGHMAN -- NHTSA; LETTER DATE D 12/20/84 FROM FRANK BERNDT -- NHTSA TO MELVIN SMITH -- ILLINOIS DOT

TEXT: Dear Ms. Jones,

This letter is in reference to a letter written by Mr. Frank Berndt to Mr. Melvin Smith of the Illinois Department of Transportation dated December 20, 1984, in which Mr. Berndt gave an interpretation of one of the requirements of FMVSS 217, a copy is at tached for your information. This interpretation concerned the location of the back of a seat with relation to the forward edge of a side emergency door. Mr. Berndt's interpretation stated that there was no tolerance permitted for the location of the s eat back with reference to a transverse plane coincident with the leading edge of the side emergency door. This lack of tolerance is what we wish to address in this letter.

As I am sure you can appreciate, a requirement for an exact location opens the door to impossible manufacturing requirements. The seats themselves, due to the use of bent-tube welded construction, can vary in the slope of the back or the relative positi on of the seat cushion, by as much as one-half of an inch. The weld-generated deformations, though slight, will also cause relative movement of the seat during the installation process of bolting the seats to the floor. Therefore, if an exact relationsh ip of any part of the seat is a requirement by law, this becomes an extremely difficult goal to meet. It will usually result in the necessity for multiple reseatings, or the physical bending of the seat after it is installed (which requires a significan t amount of force because these are seats meeting the requirements of FMVSS 222), or attempts to deform the padding of the seat locally, or some other undesireable side effect.

In light of the above considerations, and our understanding that the principle intent of FMVSS 217 in this regard is to prevent a seat back from extending backward into the door opening, we request that the NHTSA consider the following interpretation as meeting the requirements of FMVSS 217:

1. A seat back may not intrude backward into the door opening through the transverse plane coincident with the leading edge of the door opening.

2. A seat back may be located ahead of this transverse plane by no more than three-quarters of an inch, plus or minus three-quarters of an inch, or within but no more than, one and one-half inches ahead of the transverse plane coincident with the lea ding edge of the door opening. (See Fig. 1)

We would appreciate your early consideration of this interpretation, because of the current unreasonable situation that has developed among our bus users in their attempts to inspect school-buses for their compliance with their interpretations of the FMV SS 217.

Thank you.

Sincerely,

FIG 1: ALLOWABLE SEAT POSITION AT A SCHOOL BUS SIDE EMERGENCY DOOR WHEN THE BUS ALSO HAS A REAR PUSHOUT WINDOW

[DRAWING OMITTED]