Interpretation ID: aiam1065
Project Engineer
Blue Bird Body Company
Fort Valley
GA 31030;
Dear Mr. Milby: This is in reply to your letter of March 16, 1973, requesting a interpretation of the words ...unobstructed openings for emergency exit which collectively amount in total square inches...' in S5.2 of Standard No. 217, Bus Window Retention and Release'.; We believe your paragraph stating, The area credited to an emergenc exit must be the clear opening less the projected area of any obstruction in front of the exit', to be an appropriate interpretation of the phrase. We do not believe that the existence of some obstruction prevents an otherwise unobstructed opening from being used to fulfill the requirements of paragraph S5.2. You are correct in stating that whether such a window is unobstructed can be determined by utilizing the ellipsoid specified in paragraph S5.4.; You indicate in your letter you believe that if your interpretatio were applied to school buses it would result in a significant loss of seating capacity. It does not appear to us, however, that the reduction of the area of the unobstructed opening by the projected area of the obstruction, as shown in your photograph, will be significant.; Yours truly, Richard B. Dyson, Assistant Chief Counsel