CS 25.869 Fire protection: systems

These requirements, and those of CS 25.863 applicable to electrical equipment, may be satisfied by the following: 1 Electrical components in regions immediately behind firewalls and in engine pod attachment structures should be of such materials and at such a distance from the firewall that they will not suffer damage that could hazard the aeroplane if the surface of the firewall adjacent to the fire is heated to 1100°C for 15 minutes. 2 Electrical equipment should be so constructed and/or installed that in the event of failure, no hazardous quantities of toxic or noxious (e.g. smoke) products will be distributed in the crew or passenger compartments. 3 Electrical equipment, which may come into contact with flammable vapours should be so designed and installed as to minimise the risk of the vapours exploding under both normal and fault conditions. This can be satisfied by meeting the Explosion Proofness Standards of RTCA DO-160/EUROCAE ED-14.

1 High-pressure shut-off valves should be designed to provide effective slow opening and closing, so as to avoid the possible risk of fire or explosion. 2 Re-charging systems, if installed, should be provided with means to prevent excessive rates of charging which could result in dangerously high temperatures within the system. The charging system should also provide protection from contamination. 3 The compartments in which high-pressure system components, including source(s) are located should have adequate ventilation to ensure the rapid dilution of leaked oxygen. Such compartments should also provide adequate protection against contamination by liquids and other products which could result in the risk of fire. 4 Where in-situ charging facilities are provided, the compartments in which they are located should be accessible from outside the aircraft and as remote as possible from other service points and equipment. Placards should be provided, located adjacent to the servicing point, with adequate instructions covering the precautions to be observed when the system is being charged. 5 The installation of the system should be such that components and pipe lines – a. Are adequately separated from electrical and fluid systems, b. Are routed so as to minimise joints and sharp bends, c. Are clear of moving controls and other mechanisms, d. Are protected against grease or other lubricants, and are protected against the effects of vibration. In addition, joints should where possible, be assembled dry, but where compounds are used for sealing they should be approved for that purpose. 6 Where the oxygen is supplied from chemical generators, the effects of heat emission, during both normal and inadvertent operation, on both the installation and other adjacent equipment, should be taken into account.