The aviation industry prioritizes safety in the construction of aircraft, ensuring that their various components are perfectly calibrated, their systems are in working condition, and their structures are properly installed. While air travel is generally safe, emergency equipment is supplied in all aircraft to keep aircrew and passengers safe in the case of an accident. As such, this blog will provide a general overview of the emergency equipment one can find in any airplane.
Cockpit Oxygen System
The cockpit oxygen system is a conventional, high-pressure gaseous system that uses a 50 cubic foot cylinder to store oxygen at 1,850 PSI. The cylinder is typically installed on the right side of the cockpit just behind the First Officer’s seat. A removable panel behind the seat provides access to the cylinder for removal and replacement. Meanwhile, an oxygen service panel located on the right side of the front fuselage enables access to the oxygen cylinder and to a pressure gauge. A relief valve opens when the pressure exceeds 90 PSI, and a safety disc on the lower right side of the aircraft nose protects this system from over-pressurization.
Furthermore, the cylinder has a shutoff/regulator valve that controls oxygen outlet pressure and supplies cockpit oxygen at 70 PSI in the ON position. In the OFF position, the valve closes and the cockpit masks remain in their storage compartments. Cylinder pressure is displayed in the cockpit on the MFD ECS page. If the cylinder pressure drops below 400 PSI, an “EICAS OXYGEN LO PRESS” caution message will appear. Additionally, each pilot and observer is provided with a quick-donning diluter/demand type mask, which is stowed away in a mask stowage box adjacent to their respective station.
Mask Stowage Boxes
The mask stowage boxes can be found directly connected to the oxygen distribution line and the communication system. Within the boxes, one can find a mask supply hose connection and a microphone jack. Once you remove the mask from the stowage box, the box doors close without interrupting the oxygen supply. A white “OXY ON” flag will appear on the left box door, indicating that the box shutoff valve is open and oxygen is being supplied to the mask. In order to stop the oxygen flow, the left box door must be closed and the Test/Shutoff Sliding Control activated. Keep in mind that the observer’s mask stowage box does not have a Test/Shutoff Sliding Control.
As previously mentioned, the cockpit mask is a quick-donning oro-nasal type that enables oxygen to flow on demand or under pressure, as necessary. The mask is equipped with an automatic oxygen dilution system that provides pure oxygen when the cabin altitude surpasses 33,000 feet. The mask can be manually selected to the 100% position, ensuring that pure oxygen is provided at all altitudes, or to an “EMERGENCY” position to maintain positive pressure in the venting orifice.
Cockpit Fire Protection
Alongside masks, pilots are also provided with smoke goggles, but they are not a requirement. Smoke goggles are designed to fit perfectly with the cockpit mask, and metered oxygen flow is directed inside the goggle cavity to provide continuous venting.
Oxygen is generally supplied to everyone on board through chemical oxygen generators and continuous-flow masks installed in the proper dispensing units. The dispensing units are situated in the right and left overhead passenger service units, the lavatory, and the Flight Attendant station. Each unit is supplied with 1 to 3 continuous flow masks.
The Passenger Oxygen Control Panel can be found on the right lateral console, above the First Officer’s masks stowage box. If the Passenger Oxygen Latches knob is set to “AUTO” and the cabin pressure altitude exceeds 14,000 feet, the system will be automatically activated. The automatic deployment of the masks is controlled by an altimetric switch and electric latches in order to open the dispensing units.
To manually activate the system, at any altitude, the Passenger Oxygen Latches knob must be set to “MANUAL.” If the passenger oxygen system is activated and the dispensing unit door does not open, the flight attendant may manually drop them by using a door opening O2 tool. On the Passenger Oxygen Control Panel, the oxygen “ON” indicator light will become illuminated when the electric latches are energized. Moreover, the “NO SMOKING” and “FASTEN SEAT BELTS” signs in the passenger cabin will also light up.
The cylinder has about 10 cubic feet of usable oxygen. An ON-OFF regulator is positioned on the cylinder neck, alongside two outlets for connecting the two continuous-flow masks in the cylinder bag. Beyond these features, a gauge is provided to monitor the cylinder pressure.
Emergency Locator Transmitter (ELT)
The emergency locator transmitter (ELT) transmits a radio signal on 121.5 and 243.0 MHz when activated to aid in locating the aircraft during search and rescue missions. The system consists of a transmitter, an antenna, and a remote panel. The transmitter has an ON/OFF switch and an impact switch. The remote panel is located on the cockpit main panel, the transmitter is installed in the lavatory right ceiling panel, and the antenna is on the top rear of the fuselage. The ELT can be manually or automatically activated. In either scenario, a red light on the cockpit remote panel will flash to indicate activation.
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