An airship comprises an envelope accommodating hydrogen further comprising a flame arrester arrangement distributed along the envelope. The flame arrester arrangement comprises a plurality of cells made of mesh panels. The cells are adjoined the envelope and mounted end-to-end to each other.

A pressure relief assembly (24) includes an aircraft engine cowl (26) having radially outer and inner skins (28,30) having an opening. A door frame (32) is joined around the perimeter of the opening and defines a door seat (34) surrounding a central portal (36). A pressure relief door (38) is joined to the cowl (26) to cover the portal (36). The door (38) has inner and outer surfaces (40,42) terminating in a perimeter rim (44), with the inner surface (40) of the rim (44) overlapping the door seat (34) to define a primary seal (46) with the door stowed closed. A fireproof secondary seal (48) bridges the door inner surface (40) and frame (32) around the inner perimeter of the primary seal (46) to pre-seal flow to the primary seal (46).

A system configured to a plurality of zones of an aircraft includes first and second connectors are in optical communication, an optical fiber, a first interrogator, and a controller. The optical fiber extends between the first and second connectors and includes a first timing fiber Bragg grating disposed in the optical fiber at a reference location of the optical fiber. The first interrogator is connected to the optical fiber and is configured to provide a first optical signal to the optical fiber and to receive a first timing signal from the optical fiber. The first timing fiber Bragg grating is configured to provide the first timing signal with information related to the first timing fiber Bragg grating from the first interrogator. The controller is operatively connected to the first interrogator and is configured to determine the reference location of the optical fiber.

Aspects described herein generally relate to a sol-gel that is the reaction product of a hydroxy organosilane, a metal alkoxide, an acid stabilizer, and a corrosion inhibitor. The hydroxy organosilane is represented by Formula (I):

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wherein R is selected from alkyl, cycloalkyl, ether, and aryl. The acid stabilizer is at a molar ratio of acid stabilizer to metal alkoxide of 1:1 or greater and the sol-gel has a pH from about 3 to about 4.

A propulsion system comprising a nacelle substantially tubular around a longitudinal axis, having an inner wall extending from a front to a rear of the nacelle and by an outer wall, external of the inner wall, extending from the front to the rear of the nacelle, a turbojet comprising a fan and situated internally of the inner wall of the nacelle, at least one tank containing an extinguishing fluid, and a network of pipes hydraulically connected to the tank. The propulsion system comprises each tank being located in the nacelle, around the inner wall and internally of the outer wall. Such a propulsion system makes it possible to shift the one or more tanks, which no longer occupy the space at the mast, and makes it possible to carry a large volume of extinguishing fluid so as to be able to accommodate future regulations.

An aircraft fuel system architecture which reduces the fleet-wide flammability exposure of the fuel tanks. In one embodiment, the aircraft center fuel tank fuel is cooled at certain times in a flight to reduce its flammability exposure to be similar to that of an unheated conventional metal wing fuel tank. Aircraft fuel tanks that have adjacent heat sources are also insulated to minimize heat flow into the fuel. Fuel tanks that have lower cooling properties, such as composite wing tanks are cooled at certain times during flight such that their temperatures are reduced to be similar to metal wing tanks when the fuel is flammable. A fuel tank that is pressurized relative to outside pressure at altitude having a lower flammability exposure than unpressurized tanks is combined with the cooling of fuel in the tank to reduce the fleet-wide flammability exposure of the fuel tank to be similar to that of an unpressurized metal wing tank. Fuel is cooled by recirculating flow from a tank, passing through a heat exchanger and returning to the tank to be cooled. The heat exchanger is optionally cooled by flow of air from the outside of the aircraft, or by conditioned air from the aircraft environmental control system. The system is controlled by start and stop of fuel flow to the various tanks by means of a system controller. The controller uses sensors in the fuel tanks to command flow only when required to reduce the flammability exposure of the fuel tanks.

Fireworthy sealants may have a variety of compositions and be made by a variety of techniques. In certain implementations, a fireworthy sealant may include a body comprised of a cured, tacky, soft, deformable non-adhesive gel. The gel body may have an upper surface, a lower surface, and a perimeter, wherein the upper and lower surfaces of the gel body, in an uncompressed state, define a body thickness. The sealant may, in an uncompressed state, be dimensioned to fit in a first opening between a wall and an aircraft component surface and deformable when under compression to fit in a second opening, smaller than the first opening. The sealant may be flame retardant and produce low smoke density and low smoke toxicity.

A component is provided for an aircraft. This aircraft component includes an object and a multi-layer coating. The object includes an object surface. The multi-layer coating includes a barrier layer and a laminar flow layer. The covers at least a portion of the object surface. The barrier layer a fluoropolyether, a silicon rubber and/or a polyurethane. The laminar flow layer covers the barrier layer and forms an exterior surface of the component. The laminar flow layer includes a sol-gel siloxane, a rare-earth oxide and/or a phosphate.

A drain grommet with integrated fire shield. In one embodiment, the drain grommet includes a drain tube configured to extend through a drain, and to pass fluid through the drain via an opening into a hollow channel of the drain tube. The drain grommet further includes a fire shield integrally coupled with the drain tube via a standoff, wherein the standoff supports the fire shield at a vertical distance above the opening of the drain tube, and wherein the fire shield is larger than the opening of the drain tube in a horizontal plane.

A passenger cabin monitoring system includes infrared cameras disposed in respective passenger rest compartments, a flight attendant information system including at least one display and at least one speaker, and a computing device in communication with the infrared cameras and the flight attendant information system. The computing device is configured to detect a temperature of a portion of passenger rest compartment based on one or more thermal images generated by a respective infrared camera of the passenger rest compartment. The computing device is further configured to compare the temperature of the portion of the passenger rest compartment with a predetermined critical temperature and provide an audible alert and/or a visual alert via the flight attendant information system to indicate a critical status of the passenger rest compartment when the temperature of the portion of the passenger rest compartment is above the predetermined critical temperature.