DOC AIRBUS | AMM A320FFLIGHT CREW PORTABLE DEVICES - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
The flight crew emergency smoke hood provides breathable atmosphere to protect crewmembers from the effects of smoke, carbon dioxide or other harmful gases and oxygen deficiency caused by other than an airplane depressurization, while attempting to locate and/or extinguish (combat) an inflight fire on board an aircraft.
In addition, the smoke hood is designed for peak workload response that may be required for evacuation purposes, and it is further designed to continue functioning in the event of a rapid decompression.
** ON A/C NOT FOR ALL The flight crew emergency smoke hood provides breathable atmosphere to protect crewmembers from the effects of smoke, carbon dioxide or other harmful gases and oxygen deficiency caused by other than an airplane depressurization, while attempting to locate and/or extinguish (combat) an inflight fire on board an aircraft.
In addition, the smoke hood is designed for peak workload response that may be required for evacuation purposes, and it is further designed to continue functioning in the event of a rapid decompression.
2. Description
Flight-Crew Portable Oxygen Equipment(1) General description
The hood container is installed on the R aft console 702VU, it is fitted with a tamper indicator that must be broken to allow access to the bag (which contains the hood).
The container additionally provides an inspection window to allow observation of the enclosed vacuum sealed bag.
The hood container is installed on the R aft console 702VU, it is fitted with a tamper indicator that must be broken to allow access to the bag (which contains the hood).
The container additionally provides an inspection window to allow observation of the enclosed vacuum sealed bag.
(a) Hood materials of construction
- External exposed components:
Hood: Double-sided teflon-impregnated fiberglass fabric
Visor: Optically clear polycarbonate
Adjustment strap: Nomex
Adjustment buckles: Nickel-plated die-cast zinc
External thermoplastic components: Ultem
Speaking diaphragm: Kapton and glass filled nylon
External elastomers: Silicone rubber - Internal materials:
Neckseal: Latex film
Exhalation circuit: Polyurethane film
Canister discharge circuit: Teflon film
Oronasal mask: Silicone rubber
Chlorate candle: Stainless steel and brass
KO2 (potassium superoxide) canister: Tin-plated carbon steel
Canister/candle insulation: Ceramic fiber blanket and foil laminated ceramic fiber
(b) General Features
The smoke hood completely encloses the head of the wearer and seals at the neck with a thin elastic membrane. The large internal volume of the hood accommodates glasses and long hair while the elastic membrane neckseal enables fitting over the broad population range representative of aircraft crewmembers. The chemical air regeneration system is based on the use of potassium superoxide (KO2).
Operation of the hood is silently and reliably powered by the exhalation of the wearer into an oronasal mask cone located within the hood. The low moisture content of the oxygen gas generated by the KO2 bed reduces the wet bulb temperature, improving wearer comfort and controlling misting or fogging of the visor and/or glasses. The complete device is secured to the head to minimize restrictions to mobility. A neck shield extends downward from the back of the hood to protect the collar and upper shoulder area of the user from direct flame contact. A speaking diaphragm is installed in the oronasal mask cone to enhance communication.
The smoke hood completely encloses the head of the wearer and seals at the neck with a thin elastic membrane. The large internal volume of the hood accommodates glasses and long hair while the elastic membrane neckseal enables fitting over the broad population range representative of aircraft crewmembers. The chemical air regeneration system is based on the use of potassium superoxide (KO2).
Operation of the hood is silently and reliably powered by the exhalation of the wearer into an oronasal mask cone located within the hood. The low moisture content of the oxygen gas generated by the KO2 bed reduces the wet bulb temperature, improving wearer comfort and controlling misting or fogging of the visor and/or glasses. The complete device is secured to the head to minimize restrictions to mobility. A neck shield extends downward from the back of the hood to protect the collar and upper shoulder area of the user from direct flame contact. A speaking diaphragm is installed in the oronasal mask cone to enhance communication.
(c) Technical Data
Breathable gas: Chemically supplied oxygen (approximately 50 liters on demand).
Duration: 15minutes to 30 minutes when used in accordance with specified work rates.
Weight: 3.75 lb (1.7010 kg)
Starter candle: Not less than 8 liters of oxygen within 20 seconds of initiation.
Rebreathing volume: Nominal 8 liters.
CO2 Concentration: Less than 4% at maximal test condition workrate.
Inhaled gas temperature: less than 40°Celsius (Wet Bulb) at nominal test condition workrate.
Breathable gas: Chemically supplied oxygen (approximately 50 liters on demand).
Duration: 15minutes to 30 minutes when used in accordance with specified work rates.
Weight: 3.75 lb (1.7010 kg)
Starter candle: Not less than 8 liters of oxygen within 20 seconds of initiation.
Rebreathing volume: Nominal 8 liters.
CO2 Concentration: Less than 4% at maximal test condition workrate.
Inhaled gas temperature: less than 40°Celsius (Wet Bulb) at nominal test condition workrate.
(d) General Operation
During the donning sequence, the chlorate candle is automatically actuated as adjustment straps are pulled to secure the oronasal mask cone against the face. Since the neckseal is already positioned, the oxygen generated by the chlorate candle will inflate the hood, providing adequate initial breathing volume, and accomplish some purging of the hood with any excess gas generation. As the wearer begins to breathe normally through the oronasal mask cone, the exhaled breath is directed through the KO2 canister, which removes water vapor and carbon dioxide and adds oxygen before the gas is returned to the interior of the hood for inhalation.
This breathing cycle will continue until the KO2 bed is exhausted. Exhaustion of the bed results in a loss of active oxygen-generation capability coupled with a rapid increase in internal temperature and release of moisture through the KO2 bed. The loss of oxygen-generating capability results in a gradual reduction of the interior volume of the hood.
During the donning sequence, the chlorate candle is automatically actuated as adjustment straps are pulled to secure the oronasal mask cone against the face. Since the neckseal is already positioned, the oxygen generated by the chlorate candle will inflate the hood, providing adequate initial breathing volume, and accomplish some purging of the hood with any excess gas generation. As the wearer begins to breathe normally through the oronasal mask cone, the exhaled breath is directed through the KO2 canister, which removes water vapor and carbon dioxide and adds oxygen before the gas is returned to the interior of the hood for inhalation.
This breathing cycle will continue until the KO2 bed is exhausted. Exhaustion of the bed results in a loss of active oxygen-generation capability coupled with a rapid increase in internal temperature and release of moisture through the KO2 bed. The loss of oxygen-generating capability results in a gradual reduction of the interior volume of the hood.
(e) Hood Operation
The hood encloses the head of the wearer and is sealed to the wearer by the neckseal. The enclosed volume of the hood represents approximately 8 liters available rebreathing volume, or counter lung. The oronasal mask serves to direct the exhaled breath containing CO2 and water vapor back through the KO2 bed where moisture and CO2 are removed, and drier oxygen is added for return into the hood volume. Inhalation is accomplished directly from the interior of the hood through the inhalation valve located on the oronasal mask. A relief valve located at the back of the hood is used to prevent build-up of excessive pressure within the hood, and to provide emergency pressure relief in the event of a sudden reduction in cabin pressure.
The chlorate starter candle installed at the bottom of the KO2 canister, is designed to deliver a fixed volume of approximately 8 liters of oxygen over a short duration of less than 20 seconds. It is contained in a small stainless steel cylinder affixed to the base of the KO2 canister. The discharge is directed into the interior of the KO2 canister. The chlorate candle is initiated by a spring-loaded plunger striking a small percussion primer when the lanyard attached to the hood adjustment strap is pulled. The heat developed from the percussion primer is sufficient to start the decomposition reaction of the active NaClO3 material, producing oxygen and forming common salt (NaCl).
The hood encloses the head of the wearer and is sealed to the wearer by the neckseal. The enclosed volume of the hood represents approximately 8 liters available rebreathing volume, or counter lung. The oronasal mask serves to direct the exhaled breath containing CO2 and water vapor back through the KO2 bed where moisture and CO2 are removed, and drier oxygen is added for return into the hood volume. Inhalation is accomplished directly from the interior of the hood through the inhalation valve located on the oronasal mask. A relief valve located at the back of the hood is used to prevent build-up of excessive pressure within the hood, and to provide emergency pressure relief in the event of a sudden reduction in cabin pressure.
The chlorate starter candle installed at the bottom of the KO2 canister, is designed to deliver a fixed volume of approximately 8 liters of oxygen over a short duration of less than 20 seconds. It is contained in a small stainless steel cylinder affixed to the base of the KO2 canister. The discharge is directed into the interior of the KO2 canister. The chlorate candle is initiated by a spring-loaded plunger striking a small percussion primer when the lanyard attached to the hood adjustment strap is pulled. The heat developed from the percussion primer is sufficient to start the decomposition reaction of the active NaClO3 material, producing oxygen and forming common salt (NaCl).
(2) Storage
The smoke hood system is normally packaged in a two-component system consisting of a low moisture transmission aluminized vacuum-sealed bag installed in a tamper-resistant protective container. Since the active air regeneration chemical (KO2) is moisture sensitive, the primary function of the vacuum-sealed bag is to maintain an effective moisture barrier. Loss of vacuum resulting in slight inflation of the bag is an indication of loss of the moisture barrier, requiring replacement of the unit. The protective container provides a barrier to prevent accidental damage to the vacuum bag. The container is fitted with a tamper indicator that must be broken to allow access to the bag. The container additionally provides an inspection door to allow observation of the enclosed vacuum-sealed bag to verify installation and condition of the vacuum seal.
The smoke hood system is normally packaged in a two-component system consisting of a low moisture transmission aluminized vacuum-sealed bag installed in a tamper-resistant protective container. Since the active air regeneration chemical (KO2) is moisture sensitive, the primary function of the vacuum-sealed bag is to maintain an effective moisture barrier. Loss of vacuum resulting in slight inflation of the bag is an indication of loss of the moisture barrier, requiring replacement of the unit. The protective container provides a barrier to prevent accidental damage to the vacuum bag. The container is fitted with a tamper indicator that must be broken to allow access to the bag. The container additionally provides an inspection door to allow observation of the enclosed vacuum-sealed bag to verify installation and condition of the vacuum seal.