BLACK BOX FLIGHT RECORDERS BY: TASHI AGGARWAL ROLL NO -16

HISTORY  Australian scientist Dr David Warren invented the first crash and fire protected device to record both the voices and the instrument the late 1950s

Warren’s device found overwhelming industry support in the United Kingdom, where S. Davall & Son used his device as a prototype for production.

Recording and Storage  Since post-World War II era the recording medium of black boxes has evolved in order to record much more information about an aircraft's operation.  The earlier versions of black boxes, which are still in use,use magnetic tape for storing data  The Mylar tape is pulled across an Electromagnetic head, which leaves a bit of data on the tape.

Black-box manufacturers are no longer making magnetic tape recorders as airlines begin a full transition to solid-state technology The magnetic tape inside the flight data recorder from EgyptAir Flight 990, which crashed on October 31, 1999

Solid-state Technology  Solid-state recorders are considered much more reliable than their magnetic-tape counterparts  Solid state uses stacked arrays of memory boards which are about 1.75 inches (4.45 cm) in diameter and 1 inch (2.54 cm) tall.  Magnetic-tape recorders can track about 100 parameters, while solid-state recorders can track more than 700 in larger aircraft.

A solid-state recorder

Cockpit Voice Recorders (CVRs)  There are several microphones built into the cockpit to track the conversations of the flight crew  Here are the positions of the microphones: 1.Pilot's headset 2.Co-pilot's headset 3.Near the center of the cockpit, where it can pick up audio alerts and other sounds

 They use a continuous loop of tape that completes a cycle every 30 minutes. As new material is recorded, the oldest material is replaced.  Any sounds in the cockpit are picked up by these microphones and sent to the CVR, where the recordings are digitized and stored.  Most magnetic tape CVRs store the last 30 minutes of sound while solid-state storage can record two hours of audio

Flight Data Recorders (FDRs)  The FDR is designed to record the operating data from the plane's systems  There are sensors that are wired from various areas on the plane to the flight-data acquisition unit, which is wired to the FDR.  Magnetic-tape recorders have the potential to record up to 100 parameters. Solid-state FDRs can record more than 700 parameters.

 Here are a few of the parameters recorded by most FDRs: 1.Time 2.Pressure altitude 3.Airspeed 4.Vertical acceleration 5.Magnetic heading 6.Control-column position 7.Rudder-pedal position 8.Control-wheel position 9.Horizontal stabilizer 10.Fuel flow

 All of the data collected by the airplane's sensors is sent to the flight-data acquisition unit (FDAU) at the front of the aircraft.

Built to Survive  In many airline accidents, the only devices that survive are the crash-survivable memory units (CSMUs) of the flight data recorders and cockpit voice recorders.  This device is engineered to withstand extreme heat, violent crashes and tons of pressure.  Using three layers of materials, the CSMU in a solid-state black box insulates and protects the stack of memory boards that store the digitized information.

 Aluminum housing - There is a thin layer of aluminum around the stack of memory cards.  High-temperature insulation - This dry-silica material is 1 inch (2.54 cm) thick and provides high- temperature thermal protection  Stainless-steel shell- The high- temperature insulation material is contained within a stainless-steel cast shell that is about 0.25 inches (0.64 cm) thick.

Testing a CSMU  There are several tests that make up the crash-survival sequence: 1.Crash impact - CSMU us shot down an air cannon to hit an aluminum target &create an impact equal to 3,400 times its weight 2.Pin drop- A 500-pound (227-kg) weight with a inch steel pin protruding from the bottom is dropped onto the CSMU from a height of 10 feet (3 m). 3.Static crush - For five minutes, researchers apply 5,000 pounds per square-inch (psi) of crush force to each of the unit's six major axis points.

 Fire test - The unit is placed into a propane-source fireball, cooking it using three burners. The unit sits inside the fire at 2,000 degrees Fahrenheit (1,100 C) for one hour.  Other tests include: 1.Deep-sea submersion 2.Salt-water submersion 3.Fluid immersion

Underwater Locator Beacon  If a plane crashes into the water, this beacon sends out an ultrasonic pulse readily detectable by sonar and acoustical locating equipment.  The beacon sends out pulses at 37.5 (kHz) and can transmit sound as deep as 14,000 feet  Beacon is powered by a battery that has a shelf life of six years

Retrieving Information  This portable interface can allow investigators quick access to the data on a black box.  With solid-state recorders, investigators can extract stored data in a matter of minutes which takes weeks or months to complete in earlier versions

What's in store for Black Boxes?  Some form of cockpit video recorder will be developed.  The flight data recorders reporting back to a ground based system to ensure that all the data is recorded  Several automobile manufacturers eg. General Motors are utilizing black box technology in their automobiles ( Corvette)

 References