BLACK BOX

BLACK BOX

ContentS

1. INTRODUCTION

2. RECORDING AND STORAGE TECHNIQUEA. MAGNETIC TAPEB. SOLID STATE TECHNOLOGY3. COCKPIT VOICE RECORDER

4. FLIGHT DATA RECORDER

5. CONSTRUCTION

6. TESTING OF CSMU

7. AFTER CRASH

8. RETRIEVING INFORMATION

9. APPLICATIOn

10. reference

BLACK BOXABSTRACT:As the technology progressing, the speed of traveling is also increased. The source to destination became so closer to each others. The main advancement in the field of the air traveling system with the help of airplane. This is the major discovery of technology. But as the speed increases , the horror of air crash also introduced. Because at a height of 2000m and above if a plane crashes ,it will be a terror for any body. So to take the feed back of the various activities happens in the plane and record them engineers need a mechanism to record such activities .

With any airplane crash, there are many unanswered questions as to what brought the plane down. Investigators turn to the airplane's flight data recorder (FDR) and cockpit voice recorder (CVR), also known as "black boxes," for answers. In Flight 261, the FDR contained 48 parameters of flight data, and the CVR recorded a little more than 30 minutes of conversation and other audible cockpit noises.

Introduction of Black-Box

In almost every commercial aircraft, there are several microphones built into the cockpit to track the conversations of the flight crew. These microphones are also designed to track any ambient noise in the cockpit, such as switches being thrown or any knocks or thuds. There may be up to four microphones in the plane's cockpit, each connected to the cockpit voice recorder (CVR).INTRODUCTION

If any airplane crash, there are many unanswered questions as to what brought the plane down. Investigators turn to the airplane's flight data recorder (FDR) and cockpit voice recorder (CVR), also known as "black boxes," for answers. In Flight 261, the FDR contained 48 parameters of flight data, and the CVR recorded a little more than 30 minutes of conversation and other audible cockpit noises.

These recording devices, which cost between $10,000 an $15,000 each, reveal details of the events immediately preceding the accident. In this article, we will look at the two types of black boxes, how they survive crashes, and how they are retrieved and analyzed.Recording and Storage

Although many of the black boxes in use today use magnetic tape, which was first introduced in the 1960s, airlines are moving to solid-state memory boards, which came along in the 1990s. Magnetic tape works like any tape recorder. 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 recorderSolid-state TechnologySolid-state recorders are considered much more reliable than their magnetic-tape counterparts, according to Ron Crotty, a spokesperson for Honeywell, a black-box manufacturer. Solid state uses stacked arrays of memory chips, so they don't have moving parts. With no moving parts, there are fewer maintenance issues and a decreased chance of something breaking during a crash.

Data from both the CVR and FDR is stored on stacked memory boards inside the crash-survivable memory unit (CSMU). The CSMU is a cylindrical compartment on the recorder. The stacked memory boards are about 1.75 inches (4.45 cm) in diameter and 1 inch (2.54 cm) tall.

The memory boards have enough digital storage space to accommodate two hours of audio data for CVRs and 25 hours of flight data for FDRs.

Solid state recorber

Airplanes are equipped with sensors that gather data. There are sensors that detect acceleration, airspeed, altitude, flap settings, outside temperature, cabin temperature and pressure, engine performance and more. Magnetic-tape recorders can track about 100 parameters, while solid-state recorders can track more than 700 in larger aircraft.

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. This device often is found in the electronic equipment bay under the cockpit. The flight-data acquisition unit is the middle manager of the entire data-recording process. It takes the information from the sensors and sends it on to the black boxes.

BASIC COMPONET AND OPERATION OF AN AVIATION RECORDING SYSTEMBoth black boxes are powered by one of two power generators that draw their power from the plane's engines. One generator is a 28-volt DC power source, and the other is a 115-volt, 400-hertz (Hz) AC power source. These are standard aircraft power supplies, according to Frank Doran, director of engineering for L-3 Communications Aviation Recorders.

Cockpit Voice RecordersIn almost every commercial aircraft, there are several microphones built into the cockpit to track the conversations of the flight crew. These microphones are also designed to track any ambient noise in the cockpit, such as switches being thrown or any knocks or thuds. There may be up to four microphones in the plane's cockpit, each connected to the cockpit voice recorder (CVR).

Any sounds in the cockpit are picked up by these microphones and sent to the CVR, where the recordings are digitized and stored. There is also another device in the cockpit, called the associated control unit, that provides pre-amplification for audio going to the CVR. Here are the positions of the four microphones:

Pilot's headset

Co-pilot's headset

Headset of a third crew member (if there is a third crew member)

Near the center of the cockpit, where it can pick up audio alerts and other sounds Most magnetic-tape CVRs store the last 30 minutes of sound. They use a continuous loop of tape that completes a cycle every 30 minutes. As new material is recorded, the oldest material is replaced. CVRs that used solid-state storage can record two hours of audio. Similar to the magnetic-tape recorders, solid-state recorders also record over old material.

Flight Data Recorders The flight data recorder (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. When a switch is turned on or off, that operation is recorded by the FDR.

DAMAGED FDR

Magnetic-tape recorders have the potential to record up to 100 parameters. Solid-state FDRs can record more than 700 parameters.

parameters recorded BY FDRS:

Time

Pressure altitude Airspeed

Vertical acceleration

Magnetic heading

Control-column position

Rudder-pedal position

Control-wheel position

Horizontal stabilizer

Fuel flow

Solid-state recorders can track more parameters than magnetic tape because they allow for a faster data flow. Solid-state FDRs can store up to 25 hours of flight data. Each additional parameter that is recorded by the FDR gives investigators one more clue about the cause of an accident.

Built to SurviVEIn many airline accidents, the only devices that survive are the crash-survivable memory units (CSMUs) of the flight data recorders and cockpit voice recorders. Typically, the rest of the recorders' chassis and inner components are mangled. The CSMU is a large cylinder that bolts onto the flat portion of the recorder. This device is engineered to withstand extreme heat, violent crashes and tons of pressure. In older magnetic-tape recorders, the CSMU is inside a rectangular box.

solid state recorderUsing 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. We will talk more about the memory and electronics in the next section. Here's a closer look at the materials that provide a barrier for the memory boards, starting at the innermost barrier and working our way outward:

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. This is what keeps the memory boards safe during post-accident fires.

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. Titanium can be used to create this outer armor as well.

Testing a CSMU

To ensure the quality and survivability of black boxes, manufacturers thoroughly test the CSMUs. Remember, only the CSMU has to survive a crash -- if accident investigators have that, they can retrieve the information they need. There are several tests that make up the crash-survival sequence

Crash impact - . This impact force is equal to or in excess of what a recorder might experience in an actual crash.

Pin drop - To test the unit's penetration resistance, researchers drop a 500-pound (227-kg) weight with a 0.25-inch steel pin protruding from the bottom onto the CSMU from a height of 10 feet (3 m). This pin, with 500-pounds behind it, impacts the CSMU cylinder's most vulnerable axis.

Fire test - Researchers place the unit into a propane-source fireball, cooking it using three burners. .

Deep-sea submersion - The CSMU is placed into a pressurized tank of salt water for 24 hours.

Salt-water submersion - The CSMU must survive in a salt water tank for 30 days.

Fluid immersion - Various CSMU components are placed into a variety of aviation fluids, including jet fuel, lubricants and fire-extinguisher chemicals. Black boxes are usually sold directly to and installed by the airplane manufacturers. Both black boxes are installed in the tail of the plane -- putting them in the back of the aircraft increases their chances of survival. The precise location of the recorders depends on the individual plane. Sometimes they are located in the ceiling of the galley, in the aft cargo hold or in the tail cone that covers the rear of the aircraft.

"Typically, the tail of the aircraft is the last portion of the aircraft to impact," Doran said. "The whole front portion of the airplane provides a crush zone, which assists in the deceleration of tail components, including the recorders, and enhances the likelihood that the crash-protected memory of the recorder will survive.

Underwater Locator Beacon In addition to the paint and reflective tape, black boxes are equipped with an underwater locator beacon (ULB). If you look at the picture of a black box, you will almost always see a small, cylindrical object attached to one end of the device. While it doubles as a handle for carrying the black box, this cylinder is actually a beacon.

UNDERWATER LOCATOR BEACON

If a plane crashes into the water, this beacon sends out an ultrasonic pulse that cannot be heard by human ears but is readily detectable by sonar and acoustical locating equipment. There is a submergence sensor on the side of the beacon that looks like a bull's-eye. When water touches this sensor, it activates the beacon.

The beacon sends out pulses at 37.5 kilohertz (kHz) and can transmit sound as deep as 14,000 feet (4,267 m). Once the beacon begins "pinging," it pings once per second for 30 days. This beacon is powered by a battery that has a shelf life of six years. In rare instances, the beacon may get snapped off during a high-impact collision.

Retrieving InformationAfter finding the black boxes, investigators take the recorders to a lab where they can download the data from the recorders and attempt to recreate the events of the accident. This process can take weeks or months to complete. In the United States, black-box manufacturers supply the NTSB with the readout systems and software needed to do a full analysis of the recorders' stored data.

This portable interface can allow investigators quick access to the data on a black box.If the FDR is not damaged, investigators can simply play it back on the recorder by connecting it to a readout system. With solid-state recorders, investigators can extract stored data in a matter of minutes. Very often, recorders retrieved from wreckage are dented or burned. In these cases, the memory boards are removed, cleaned up and a new memory interface cable is installed. Then the memory board is connected to a working recorder. This recorder has special software to facilitate the retrieval of data without the possibility of overwriting any of it.

Both the FDR and CVR are invaluable tools for any aircraft investigation. These are often the lone survivors of airplane accidents, and as such provide important clues to the cause that would be impossible to obtain any other way. As technology evolves, black boxes will continue to play a tremendous role in accident investigations.

OTHER USES FOR BLACK BOX TECHNOLOGY

Currently, black boxes aren't just taking flight -- they're being grounded as well. Several automobile manufacturers are utilizing black box technology in their automobiles and a few have been doing so for quite some time. According to an article titled "Black boxes in GM cars increasingly help police after accidents" General Motors has been using black box technology for over a decade.

So, black box technology has moved from airplanes to automobiles -- where is it headed next? It could be on you. Right now it's just a prototype, but soon the SenseCam could provide you with an incredible amount of information about -- well, you!

Advantages and Disadvantages of Black Box Testing

Advantages of black box testing:

Black box tests are reproducible.

The environment the program is running is also tested.

The invested effort can be used multiple times.

Disadvantages of black box testing:

The results are often overestimated.

Not all properties of a software product can be tested

.

The reason for a failure is not found.

CONCLUSION

So, black box technology has moved from airplanes to automobiles -- where is it headed next?

There are improvements on the horizon for black box technology. Reportedly, some form of cockpit video recorder will be developed. Such a recorder would be able to store video images in solid-state memory.PAGE MKITW,ECE,RajampetPage 12