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Fire and overheat detection

Meggitt Safety Systems supplies the aviation industry with pneumatic, continuous length fire/overheat detectors. Our pneumatic detectors are currently protecting the engines and Auxiliary Power Units of many commercial, military, and general aviation aircraft and helicopters.

Meggitt's fire/overheat detectors are virtually maintenance free, have logged over 500 million flight hours on commercial jet transports, and have never missed a true fire warning. Our pneumatic fire and overheat detectors provide safety critical condition awareness in engines, main landing gear and auxiliary power units.

Proven performance is a key characteristic of the Safety Systems' detector. While reliability is designed into Safety Systems' critical fire and smoke detection hardware, quality is built in and continually verified through rigorous inspection and test. All detectors are closely inspected during production and 100% tested before they are certified for delivery. The hermetically-sealed units require no scheduled maintenance, withstand high temperature and high vibration and are inherently immune to false alarms. Designed and manufactured using proprietary processes, they can be installed on pre-formed support tubes or mounted directly, with Meggitt aircraft system controllers providing the interface between detection and extinguishing systems.

Applications include:

  • Boeing 707, 727, 737 (including next-generation 737), 747, 757, and 767;
  • McDonnell Douglas DC-10 and MD-11;
  • Airbus A300, A310, A320, A330, and A340;
  • Embraer 110/120/145;
  • U.S. Air Force F-4, F-111, F-15, and C-141;
  • U.S. Navy F/A-18 C/D & E/F;
  • BAe 146, Beechcraft Starship, and Cessna Citation III & X;
  • Augusta A109 and A129.

Meggitt's ultra stable lightweight silicone dioxide cable, proven in military jets and nuclear installations, can perform for decades in extreme environments. This hermetically-sealed metal-jacketed cable can transmit coaxial, electrical and digital signals during major fires. It maintains stability and performance at high temperature and vibration where conventional organic and Teflon cable fail.

Because Meggitt's fire detectors are uniquely constructed to reduce false fire events-even if bent, crimped or dented-you won't be surprised to learn that 85 per cent of new aircraft choose this technology.

  • Flame response: alarm signal within five seconds when subjected to a 1100C, six-inch flame
  • Vibration resistance: 45 grms
  • Temperature tolerance: continuously up to 343C
  • Success rate: no true fire alarms missed in over one billion flying hours

Meggitt's continuous-length pneumatic detector consists of a housed responder assembly with a length of stainless steel sensor tubing permanently attached. The entire assembly is welded, brazed, and hermetically sealed.

Enclosed within the sealed responder housing are pressure-sensitive alarm and integrity switches and an electrical connector or mating stud for connection to aircraft wiring. The detector's sensor tube contains a special core material and is pressurized. When the ambient temperature around the detector rises to a factory pre-set level, the gas pressure within the tube increases. This increased pressure closes the alarm switch, providing an electrical connection between a power source and the aircraft's alarm indication devices. When the temperature decreases, the alarm switch opens, and the detector is ready to respond again.

The pneumatic detector also provides discrete sensing for localized high intensity heat. The special core material has the unique property of releasing an extremely large volume of gas when any short section of the sensor is heated to a discrete temperature. The central core releases active gas quickly (avalanche like), increasing pressure in the sensor and actuating the alarm pressure switch. Upon removal of the heat source and sensor cooldown, the reverse process takes place. The central core reabsorbs the active gas. The pressure switch snaps back to the open position and the detector is once again in a ready condition. Thus, there are two separate temperature hazards which the detector element will quickly sense and respond to - a general overheat or a localized hot spot.

For new generation aircraft applications, Whittaker has developed a single stud detector, which also operates on the proven pneumatic principle. The responder assemblies have been repackaged to reduce weight and optimize reliable operation.

High temperature switch components and ceramic potting compound provide increased resistance to the high temperatures and extreme vibrations of today's turbofan engines. Single stud detectors not only lower system cost and weight but also achieve a secondary weight reduction in associated aircraft wiring.

   
     

©2005-2014 Meggitt Safety Systems
Meggitt Safety Systems is a Meggitt group company.