NTSB · Safety Recommendation
Safety Recommendation A-73-120
Recommendation
EFFECT RETROACTIVE MODIFICATIONS ON ALL SUBJECT AIRCRAFT TO ENSURE FULL COMPLIANCE WITH PROVISIONS OF FAR 25.855 AND 25.857 PERTAINING TO PREVENTION OF HAZARDOUS QUANTITIES OF SMOKE, FLAMES, OR NOXIOUS GASES FROM ENTERING THE FLIGHTCREW COMPARTMENT.
Safety Issue and Context
INVESTIGATION OF THE PAN AMERICAN WORLD AIRWAYS, INC., BOEING 707 ACCIDENT AT BOSTON, MASSACHUSETTS, ON NOVEMBER 3, 1973, HAS DISCLOSED SOME FINDINGS ABOUT WHICH THE NATIONAL TRANSPORTATION SAFETY BOARD IS CONCERNED.
Response History
January 11, 1974 · Recipient Response · FAA
1/11/74 RESPONSE FROM THE FAA TO SAY THAT THEY ARE PRESENTLY ASSESSING THE ADEQUACY OF THE CABIN SMOKE EVACUATION PROVISIONS ON THE 707. THIS WILL INVOLVE A REVIEW OF THE DESIGN, PAST TESTING AND THE TESTING PRESENTLY BEING CONDUCTED BY THE MANUFACTURER. BASED UPON THEIR FINDINGS OF THIS ASSESSMENT, THEY WILL, TOGETHER WITH THE MANUFACTURER, DEVELOP ANY NEEDED CORRECTIVE ACTIONS IN CONSONANCE WITH THE BOARD RECOMMENDATIONS. 1/25/74 FURTHER RESPONSE FROM THE FAA STATING THAT DURING THE CERTIFICATION PROGRAM, THE 707-321C CONFIGURATION AND THE ASSOCIATED SMOKE CHUTE INSTALLATION WAS FLIGHT TESTED WITH LARGE QUANTITIES OF SMOKE GENERATED IN THE CLASS E CARGO COMPARTMENT.
WHEN SPECIFIED EMERGENCY PROCEDURES WERE FOLLOWED, SMOKE WAS EXCLUDED FROM THE COCKPIT, THUS SHOWING COMPLIANCE WITH THE SMOKE EXCLUSION PROVISIONS OF FAR 25.855 AND 25.857. MEANS ARE PROVIDED TO SHUT OFF THE NORMAL VENTILATING AIRFLOW TO THE CLASS E CARGO COMPARTMENT AS REQUIRED BY FAR 25.857(E)(3). FURTHER VISUAL OBSERVATION DURING THE ABOVE FLIGHT TESTS CONFIRMED THAT THERE WAS NO REVERSE AIRFLOW THROUGH THE SMOKE CHUTE DURING SMOKE EVACUATION TESTS. SEPERATE FLIGHT TESTS WERE PERFORMED TO SHOW COMPLIANCE WITH THE SMOKE DETECTION PROVISIONS OF FAR 25.857.
THE FAA IS FURTHER INVESTIGATING THE NEED TO IMPROVE THE EMERGENCY SMOKE EVACUATION PROCEDURES WITH RESPECT TO CLARITY AND OPERATIONAL USE. FURTHER INVESTIGATION WILL DETERMINE WHETHER IMPROVED AIR CARRIER SMOKE EVACUATION PROCEDURES ARE WARRANTED.