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Aircraft Safety Systems FLT 241

Key Terms

  • Fly-by-Wire-
  • Extended Range Twin Engine Operations
  • High Lift Systems
  • Antiskid System
  • Engineered Materials Arrestor Systems (EMAS)
  • Aging Aircraft Safety Rule (AASR)
  • Widespread Fatigue Damage (WFD)
  • Primary Flight Display (PFD)
  • Multifunction Display (MFD)
  • Liquid Crystal Display (LCD)
  • Electronic Flight Bag (EFB)
  • Traffic Collision Avoidance System (TCAS)
  • Wing Spoilers (speed brakes)
  • Thrust Reversers
  • High Altitude Clear Air Turbulence (HICAT)
  • Wind Shear
  • Ground Proximity Warning System (GPWS)
  • Engine Indicating and Crew Alerting System (EICAS)
  • Aircraft Communications Addressing and Reporting Systems (ACARS)
  • Flight Management System (FMS)
  • Central Maintenance Computer System (CMCS)
  • Synthetic Vision System (SVS)
  • Heads Up Display (HUD)
  • Flight Data Recorder (FDR)
  • Cockpit Voice Recorder (CVR)

Jet Engine Development

Credit for the jet engine goes to two individuals who worked independently of each other just prior to and during World War II: Frank Whittle of England and Hans von Ohain of Germany.

How does a Jet Engine Work?

Recent Developments in Jet Engine Design

  • Next generation aircraft are making maximum use of the latest composite materials and design processes to reduce weight, improve performance and lower maintenance cost.
  • Light weight composites consists of the following: Graphite, Kevlar and fiberglass are being used throughout the aircraft main structure and as fan blades in jet engines where the operating temperatures are low.

Long-Range Commercial Jet Transport Era

With the introduction of the Boeing B-47, military jet bomber allowed manufacturer to a great leap forward in commercial transport airplanes. This airplane incorporates a radical airframe differences that included:

  • Highly Swept Wing (35 Degrees)
  • High Aspect Ratio Plan Form (9.43)
  • Very Wide Speed Range
  • Long Duration- High Alitude Operation
  • High Wing Loading
  • Thin Wing (12% constant thickness ratio)
  • An extremely clean aerodynamic design
  • Pod- mounted engines

This design produced a revolutionary performance advantage but also presented real safety challenges requiring technological solutions. Some of these challenges involved:

  • How to take off and land
  • Stopping distance considerations
  • Control system capability over a large speed range, and flutter
  • Structural integrity for this wing plan form and speed range

These challenges were mitigated with the following solutions:

High Lift Systems

Stopping Systems

A number of improvements in aircraft stopping systems have taken place over the years, greatly enhacing safety. They include antiskid, fuse plugs, autobrakes, speed brakes and thrust reversers.

Engineered Materials Arrestor System (EMAS)

FAA requires that commercial airports certified under FAR Part 139 have a Runway Safety Area of 1000 feet beyond the end of the runway if possible. Currently, EMAS is installed at 51 runway ends at 35 U.S. Airports, and has been credited with several successful arrest- ments preventing injury and aircraft damage.

Autobrakes

Autobrakes

This system enables automatic brake application on landing or during a refused takeoff (RTO). The landing autobrake system controls brake pressure to maintain aircraft deceleration at one of five pilot selected values, provided that sufficient runway friction is available to maintain this level.

Speedbrakes

The use of wing spoilers (speedbrakes) is to allow airplanes to slow down in flight and also help in braking on the ground by automatic deployment.

Thrust Reversers

Allow aircraft to redirect the airflow in order to assist in stopping airplanes.

Structural Integrity

The B47 and the De Havilland Comet were the first large jets to become operational, and both encountered fatigue problems. The comet encountered fuselage skin fatigue problems that led to a series of accidents. Subsequent investigation into these and the B-47 fatigue problems pushed the state of the art for aircraft structural design technology forward very rapidly.

Structural Safety

Criteria and procedures used in commercial airplane design over the last three decades have produced long- lived, damage tolerant structures with excellent safety records. these design concepts, supported by testing, have worked well due to the system that is used to ensure that the fleets of commercial jet transports are kept flying throughout their service lives. This system has three major participants:

Aging Aircraft

One of the major problems facing the FAA and air carriers today is aging aircraft. By definition, aging aircraft are aircraft that are being operated near or beyond their originally projected design goals of calendar years, flight cycles, or flight hours.

Cabin Safety

In 1985, the NTSB addressed the issue of safety on several fronts. It issued a study on emergency equipment and procedures relating to in-water air carrier crashes. The study found that equipment and procedures were either inadequate or designed for ditching rather than for the more common short (or no warning in-water crashes). Ten years later improvement were made and contained the following:

  • Fire-blocking seat cushions to prevent fire or to mitigate its effects.
  • Emergency floor lighting to improve the chances and speed of evacuation by 20% under conditions where there is significant smoke in the cabin. Improved passenger safety briefings and cabin safety data cards have also made a positive impact.
  • Stronger seats that must be able to withstand 16 times the force of gravity (16Gs) are required for Part 121 aircraft that were built after October 27, 2009. Using a test dummy, these seats must undergo dynamic testing and evaluation to ensure they are effective in the demanding aviation crash environment.

Safety Design For Atmospheric Conditions

  • Turbulence
  • Wind Shear
  • Volcanic Ash
  • Ice and Precipitation

Turbulence

One of the most dangerous forms of turbulence for aircraft is:

  • Clear Air Turbulence
  • High Altitude Clear Air Turbulence

Between 1983 and 1997, the NTSB investigated 99 turbulence accidents and incidents that resulted in two fatalities and 117 serious injuries.

In order to prevent such incidents and accidents the NWS Aviation Weather Cewnter and NOAA Earth System research Laboratory are also making progress in improving its CATand mountain wave forecast products. Further, the FAA Aviation Weather Research Program has a multidisciplinary team addressing the turbulence problem, and researchers from the National Center for Atmospheric Research (NCAR) are working on new algorithms for using data from the NWS Doppler Weather Radars to detect turbulence.

Windshear

Variation in wind velocity occurring along a direction at right angles to the wind's direction and tending to exert a turning force.

Volcanic Ash

On April 14, 2010 issued an alert that a strong ash plume was moving from the eruption of "Eyjafjallajokull" also known as E+15 volcano in Iceland toward Northwestern Europe. This day became known as "ash Thursday" by the airline industry: over 17,000 flights were cancelled on some days, incurring losses of some $200 million per day,

Ice and Precipitation

In- flight icing is one of the FAA's top weather priorities. Under revised certification standards, new transport aircraft designs must incorporate one of three methods to detect icing and to activate the airframe ice protection system:

  • An ice detection system that automatically activates or alerts pilots to turn on the ice protection system.
  • At definition of visual signs of ice buildup on a specified surface combined with an advisory system to alert the pilots to activate the ice protection system; or
  • The identification of temperature and moisture conditions conducive to airframe icing that would alert pilots to activate the ice protection system.

Flight Deck Human- Machine Interface

Technology in flight decks has improved continuously since the early days of aviation. The following are some of the flight deck technology changes that have made significant contribution to improving safety.

  • crew Alerting and Monitoring Systems
  • Simple System Designs
  • Redundant Systems
  • Automated Systems (when essential)
  • Moving Map Display
  • Engine Indicating and Crew Alerting System (EICAS)
  • Glass Cockpit Displays with Color Enhancements
  • Ground Proximity Warning System (GPWS)
  • Traffic Collision Avoidance System (TCAS)
  • Aircraft Communications Addressing and Reporting Systems (ACARS)

Modern Aircraft Flight Deck

New Cockpit Enhancements

  • Glass Cockpit, three axis digital fly-by-wire flight control system with a convention control yoke rather than side stick controller.
  • Flight, navigational and engine information is presented on six large display screens with advanced liquid crystal (LCD) technology.
  • An integrated Airplane Information management System which provides flight crews information regarding the overall condition of the aircraft, maintenance requirements, and key operating functions.
  • Ground Maneuver camera system with video views of the nose and main landing gear to assist the pilot with ground handling when at the gate area.

Crew Alerting Systems

  • Advanced Ground Proximity Warning System (EGPWS)- advanced terrain warning system used in most modern commercial airline fleets. The EGPWS improves situational awareness and increases warning times by using a terrain database that compares actual location of the aircraft to terrain in the database and uses a "look ahead' feature to detect what terrain ahead of the flight path may pose risk.
  • Traffic Collision Avoidance Systems (TCAS)- This is an electronic aircraft collision warning system to help prevent dangerous midair collision accidents, which as one might imagine are often associated with great loss of life.

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