Fire and Smoke — Page 160, Lesson 251

I want to walk you through the opening of the Fire and Smoke chapter. This is a critical topic because, by the inherent nature of the machine, fire is always a potential hazard where aeroplanes are concerned. Let me break down exactly why that is. The environment inside an aeroplane is volatile for fire to occur for several reasons. First, we carry fuel that has a relatively low flash point — that means it can ignite at a comparatively low temperature. Second, we have hot gases and hot materials from the engines and other systems. Third, there is extensive use of and distribution of electricity throughout the aircraft. And fourth, there is human interference — mistakes or actions by people. On top of all that, we have an ample supply of additional combustible material in the form of furniture, clothing, and the contents of luggage and freight. So the situation is created where, in any emergency situation, consideration of potential fire must be procedurally catered for — meaning the procedures must account for the possibility of fire. Now, let's look at how this is addressed in design and operations. In the design of the aeroplane, the manufacturer is required to build in fire detection and fire protection systems. The manufacturer also details the correct use of these systems in the aeroplane manual, which contains the checklists. Likewise, any maintenance schedule will contain procedures to reduce the possibility of fire during routine or non-scheduled maintenance. On the operator's side, the operator is required to include procedures in the Operations Manual — the OM — for abnormal and emergency operations. Action-specific checklists may either be verbatim extracts from the OM, or extracts or annexes from the aircraft manual. In any case, such emergency drill action checklists are to be carried in the aeroplane — they must be physically on board. The majority of situations to be catered for include engine fires, fires in the cabin or the flight deck, hot brakes, and the ingress of smoke and fumes into the aeroplane. This list is not exhaustive, but these are the main categories. The actions required are general in concept but modified by the individual type requirement — meaning the basic idea is the same across aircraft types, but the specific steps depend on the particular aeroplane you're flying. Let me give you one specific example that the excerpt introduces. A fire in the carburettor of a piston engine during engine start can be caused either by malfunction of the engine — such as incorrect valve clearance or valve failure — or by poor engine starting technique, specifically 'pumping' the throttle. That's where you move the throttle back and forth excessively during start, which can introduce too much fuel and cause a fire. So to summarise: fire is a constant hazard in aviation because of fuel, heat, electricity, combustible materials, and human factors. The manufacturer builds in detection and protection systems and documents them. The operator writes procedures into the OM and carries emergency checklists on board. And the specific emergencies — engine fires, cabin or flight deck fires, hot brakes, smoke and fumes — all require actions that are general in concept but tailored to the aircraft type.