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With reference to your recommendation to relocate the generator leads, the present electrical leads in the area of the fuel line will be rerouted to a near center position in the fuselage to separate them as far as practicable from the fuel lines. A teflon type cover is being considered for the generator leads so that even if the bus is ruptured due to an impact load, the flexible cover will remain intact under deflection and thus reduce the likelihood of ignition of a fire.
We note your observations concerning landing gear failure on the Boeing 727. An engineering review of the landing gear design has been completed and the conclusion reached that a corrective measure is needed. The change will improve the response rate of the upper side brace tube attachment fitting so that without reducing the strength of this fitting for normal loads, the attachment fitting will fail after a small angle rotation toward the rear. A retrofit design change is in process.
Emergency cabin lighting systems
With reference to your recommendation concerning emergency lighting system operation and design, the emergency cabin lighting circuitry is being looked at very carefully. The present system provides for the battery powered emergency lights to go on after an interruption of either DC or AC power. The burning of the emergency lights during each takeoff and landing would deplete the batteries which have approximately 20 minutes capacity. The recharging rate would not be sufficient to assure emergency lights when needed. Our evaluation has not yet been completed of the full impact of the re-engineering and modification of systems to provide the capability of manually turning on emergency exit lights using airplane power during each-takeoff and landing. Our attention will be given to similar designs in other transport aircraft.
Flammability of cabin interior materials
The Agency endorses and has recognized the need for more stringent requirements to define the characteristics of cabin materials when exposed to fire. Research action to improve these standards was initiated in early 1963 to investigate this problem. Subsequently Federal Aviation Agency Technical Report No. ADS-3, dated January 1964, and entitled "Flammability and Smoke Characteristics of Interior Aircraft Materials," served as part of our basis for a related regulatory project. Proposed new fire protection standards for aircraft cabin interior materials are being processed by the Agency to require self-extinguishment burn characteristics for such
