Interpretation ID: 19437-1.pja
Mr. Robert Douglas
Director of Product Integrity
AmTran Corporation
P.O. Box 6000
Conway, AR 72033
Dear Mr. Douglas:
This responds to your letter to James Jones of our Safety Assurance Office requesting an interpretation of Federal Motor Vehicle Safety Standard No. 217, Bus emergency exits and window retention and release. Your letter was forwarded to my office because the Office of the Chief Counsel responds to requests for interpretation. AmTran manufactures a school bus with a rear push out window, and you want to know whether the window is large enough to meet the specifications in Standard No. 217. As explained below, your window is not big enough.
From the drawing you enclosed, it appears that the height of the window opening on the interior wall of the bus is about 41.9 centimeters (cm) high. The window is hinged at the top, and when opened the bottom edge swings upward and outward with the assistance of "gas springs." When fully opened, the plane of the window inclines at its outward edge toward the ground at approximately 15 degrees. At the top and bottom of the window, there is a frame that projects toward the interior of the bus, perpendicular to the window surface. As the window rotates open, the interior edge of the frame rotates outward and downward, reducing the window opening by 3.1 cm, to 38.8 cm.
The pertinent part of S5.2.3.1(b)(1) specifies "a push out rear window that provides a minimum opening clearance of 41 centimeters high and 122 centimeters wide . . .." (emphasis added). We cannot agree with your suggestion that the window opening constitutes the "hole in the body with trim." The words "opening clearance" mean that the exit must meet the clearance specification when the emergency exit window is open. We would measure the exit with the window open during compliance testing because that is the actual opening that would be provided to the passengers in an emergency. The opening needed to comply with the standard must be at least a 41 cm by 122 cm rectangle extending from the interior wall of the bus all the way through to the exterior when the window is opened.
The opening on the rear emergency exit window of your bus is only 38.8 cm high when the window is open, 2.2 cm less than the specified minimum height. Thus, we conclude that your emergency exit window design does not comply with S5.2.3.1(b) of Standard No. 217. The additional fact that you mention, that the window may satisfy the separate requirement of S5.4.2.1(c) involving the passage of the ellipsoid, does not have any bearing on its compliance with S5.2.3.1(b).
I hope that this information has been helpful. If you have any further questions, feel free to contact Paul Atelsek of my staff at (202) 366-2992.
Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:217
d.6/1/99
1. Although your letter referred to S5.2.2.2(b), we assume you meant S5.2.3.1(b), which corresponds to the quotation you included.