110
Status Lights Status lights are normally green, blue, or white. These indicate operation of systems that should be monitored or recognized by the pilots but that in themselves do not represent abnormal situations. Ice vane deployment on turboprops and bleed-powered ice protection systems on jets fall into this category. Fuel crossfeed is another such condition. Airplane systems vary so much by aircraft type that what justifies a status light on one airplane may dictate a caution light on another and may be unindicated on a third. Status lights are sometimes installed on the same panel with caution and warning annunciators or may otherwise be scattered around the cockpit, depending on aircraft type.
Audio Advisory and Warning Annunciation Every turbine aircraft you fly will likely have some sort of an audio advisory and warning system used in conjunction with annunciator and warning systems. Like annunciator lights, these audio systems are designed to advise the flight crew of the status or operation of certain aircraft systems and to warn the flight crew in the event of an impending emergency situation. A variety of audio signals may be found on typical turbine aircraft: bells, horns, chimes, clackers, verbal speech, and C-chord signals, to name a few. Some turbine aircraft may have dozens of different aural signals, and you will be required to know them all. One popular turboprop associates all warning and caution lights with specific audio chimes. If a red warning light illuminates, it is accompanied by a triple chime, while an amber caution light is accompanied by a single chime. The audio warning chime is repeated every five seconds until the flight crew cancels it by pressing the appropriate master warning or master caution light switch.
Takeoff Configuration Warning System One specific type of warning system often found in turbine aircraft is the takeoff configuration warning system (TOCWS). This system is designed to warn pilots when an aircraft is not properly configured for takeoff. The TOCWS monitors flap and spoiler positions, trim settings, parking brake status, and a number of other parameters, depending on the
THE TURBINE PILOT’S FLIGHT MANUAL
airplane (for example, gust locks or condition lever settings in turboprops). If any monitored controls or flying surfaces are in positions not conducive to safe takeoff, a horn sounds and a caution light illuminates upon application of takeoff power by the pilots. The takeoff configuration warning system can be reset by retarding throttles to idle and reconfiguring the aircraft properly for takeoff.
Fire Protection Systems A fire is absolutely one of the gravest emergencies that can occur in an airplane. Therefore, numerous systems are installed to combat them. Preflight and before-start checklists always call for fire system tests, as do APU start procedures. Some evidence suggests that most aircraft fire events are over in less than 20 minutes — successfully or unsuccessfully. Clearly, any in-flight fire dictates immediate emergency action, followed by landing as soon as possible. As you might expect, most larger aircraft have built-in fire detection and/or extinguishing systems. These systems vary tremendously in detail, based on aircraft type, but there are a number of commonalities.
Fire Detection and Extinguishing Systems Turbine engines are virtually always monitored for fire. Obviously, the combined presence of heat, fuel, and existing combustion makes engine nacelles potentially dangerous. Fire detection in engine compartments may be accomplished in several manners. The most common is via a system of fire loops, installed around the engines so as to pass through the most likely areas where an uncontained fire could develop. Fire loops operate on the principle that the electrical resistance of a material changes with temperature. Excessive heating of any area on a fire loop signals a nearby detector that electrical resistance has changed and, therefore, that a fire may exist. Another type of fire detection system operates optically. Infrared light (heat) that exceeds a certain threshold triggers a fire warning. (Optical fire detection systems are subject to false alarms in some aircraft, where sunlight at certain angles can trigger the detectors.)
