Critical engine

Description

When one of the engines on a typical multi-engine aircraft becomes inoperative, a thrust imbalance exists between the operative and inoperative sides of the aircraft. This thrust imbalance causes several negative effects in addition to the loss of one engine's thrust. For reasons listed below, the left engine of a conventional twin-engine propeller-driven aircraft is typically considered critical.

[edit] Factors affecting engine criticality

[edit] Asymmetrical yaw

When one engine becomes inoperative, a torque will be developed which depends on the lateral distance from the center of gravity (C.G.) to the thrust vector of the operating engine multiplied by the thrust of the operating engine. The torque effect attempts to yaw the aircraft's nose towards the inoperative engine, a yaw tendency which must be counteracted by the pilot's use of the flight controls. Due to P-factor, the right-hand engine typically develops its resultant thrust vector at a greater lateral distance from the aircraft's C.G. than the left-hand engine. The failure of the left-hand engine will result in a larger yaw effect via the operating right-hand engine, rather than vice-versa. Since the operating right-hand engine produces a stronger yaw moment, the pilot will need to use larger control deflections in order to maintain aircraft control. Thus, the failure of the left-hand engine is less desirable than failure of the right-hand engine, and the left-hand engine is critical.

It is important to note, however, that this example depends upon both propellers turning clockwise as viewed from the rear. On aircraft with counterclockwise-turning engines (such as the de Havilland Dove), the right engine would be critical.

Aircraft which have counter-rotating propellers rotating toward the cockpit on the top side (such as the Beechcraft Duchess) do not have a critical engine, while both engines are critical on aircraft with counter-rotating propellers turning away from the cockpit. The Lockheed P-38 was an example of the latter.

The operating right-hand engine will produce a more severe yaw towards the dead engine, thus making the failure of the left-hand engine critical

[edit] Accelerated Slipstream

Lift can be roughly defined as an upwards force resulting from an airstream going over and under a wing. On aircraft with propellers mounted on the wing, the propwash from the engine will accelerate the airstream over the portion of the wing directly behind the propeller. This results in greater lift behind the propeller than at other spots on the wing. From the P-factor effect, the right wing's center of lift will be further from the C.G. than the left-hand wing. While failure of either engine will cause a rolling motion towards the inoperative side, the rolling motion will be more severe with the right engine operating. Thus, the failure of the left-hand engine is critical. Again, this example depends on both engines turning clockwise when viewed from the rear.

[edit] Spiraling Slipstream

Air forced backwards from the propellers tends to spiral as it moves rearward.

[edit] Non-aerodynamic criticality

On certain aircraft, hydraulic, pneumatic or electrical systems may be powered by one engine. This engine would therefore be critical in this respect.

[edit] References

Airplane Flying Handbook. U.S. Government Printing Office, Washington D.C.: U.S. Federal Aviation Administration. 2004. pp. 12–27 to 12–28. FAA-8083-3A. http://www.faa.gov/library/manuals/aircraft/airplane_handbook/.

Garmin 1000 system

Components

An aircraft with a basic Garmin G1000 installation contains two LCD displays (one acting as the primary flight display and the other as the multi-function display) as well as an integrated communications panel that fits between the two.

Beyond that, additional features are found on newer and larger G1000 installations, such as in business jets. This includes:

• A third display unit, to act as a co-pilot PFD
• An alphanumeric keyboard
• An integrated flight director/autopilot (without it, the G1000 interfaces with an external autopilot)

Depending on the airplane manufacturer and whether or not a GFC 700 autopilot is installed, the G1000 system will be comprised of either 2 GDU 1040 displays (no autopilot), a GDU 1040 PFD/GDU 1043 MFD (GFC 700 autopilot installed), or a GDU 1045 PFD/GDU 1045 MFD (GFC 700 autopilot installed with VNAV).

The GDU 1040 is the standard base bezel with no autopilot/flight director mode selection keys below the heading bug. The GDU 1043 has autopilot/flight director keys for all GFC 700 modes except VNAV. The GDU 1045 is essentially identical to the GDU 1043 except for the addition of an autopilot/flight director mode for VNAV. Depending on how the units are installed, an MFD failure may, or may not, have an impact on autopilot or flight director use. If a GDU 1040 is used as a PFD in an airplane equipped with a GFC 700 autopilot, a failure of the MFD (which houses the autopilot mode selection keys) will leave the autopilot engaged, but the modes cannot be changed because no autopilot keys are present on the PFD. But, if an MFD failure occurs in an airplane with the GFC 700 autopilot and either a GDU 1043 or a GDU 1045 bezel installed as a PFD, the pilot will have full use of the autopilot through the keys on the PFD.

Both the PFD and MFD each have two slots for SD memory cards. The top slot is used to update the Jeppesen aviation database every 28 days. The aviation database must be current to use GPS for navigation during IFR instrument approaches. The bottom slot houses the World terrain and Jeppesen obstacle databases. While terrain information rarely changes or needs to be updated, obstacle databases can be updated every 56 days through a subscription service. The top card can be removed from the G1000 system following an update, but the bottom card must stay in both the PFD and MFD to ensure accurate terrain awareness and TAWS-B information.

[edit] Primary flight display (PFD)

Screenshot of the PFD on the G1000

The primary flight display shows the basic flight instruments, such as the airspeed indicator, the altimeter, the heading indicator, and course deviation indicator. A small map called the "inset map" can be enabled in the corner. The buttons on the PFD are used to set the squawk code on the transponder. The PFD can also be used for entering and activating flight plans. The PFD also has a "reversionary mode" which is capable of displaying all information shown on the MFD (for example, engine gauges and navigational information). This capability is provided in case of an MFD failure.

[edit] Multi-function display (MFD)

The MFD usually shows engine instrumentation and a moving map.

The multi-function display typically shows a moving map on the right side, and engine instrumentation on the left. Most of the other screens in the G1000 system are accessed by turning the knob on the lower right corner of the unit. Screens available from the MFD other than the map include the setup menus, information about nearest airports and NAVAIDs, Mode S traffic reports, terrain awareness, XM radio, flight plan programming, and GPS RAIM prediction.

[edit] Implementation

The G1000 system consists of several integrated components which sample and exchange data or display information to the pilot.

[edit] GDU Display

The GDU display unit acts as the primary source of flight information for the pilot. Each display can interchangeably serve as a primary flight display (PFD) or multi-function display (MFD). The wiring harness within the aircraft specifies which role each display is in by default. All of the displays within an aircraft are interconnected using a high-speed Ethernet data bus. A G1000 installation may have two GDUs (one PFD and one MFD) or three (one PFD for each pilot and an MFD). There are several different GDU models in service, which have different screen sizes (from 10 inches to 15 inches) and different bezel controls.

In normal operation, the display in front of the pilot is the PFD and will provide aircraft attitude, airspeed, altitude, vertical speed, heading, rate-of-turn, slip-and-skid, navigation, transponder, inset map view (containing map, traffic, and terrain information), and systems annunciation data. The second display, typically positioned to the right of the PFD, operates in MFD mode and provides engine instrumentation and a moving map display. The moving map can be replaced or overlaid by various other types of data, such as satellite weather, checklists, system information, waypoint information, weather sensor data, and traffic awareness information.

Both displays provide redundant information regarding communications and navigation radio frequency settings even though each display is usually only paired with one GIA Integrated Avionics Unit. In the event of a single display failure, the remaining display will adopt a combined "reversionary mode" and automatically become a PFD combined with engine instrumentation data and other functions of the MFD. A red button labeled "reversionary mode" or "display backup," located on the GMA audio panel, is also available to the pilot to select this mode manually if desired.

[edit] GMA Audio Panel

The GMA panel provides buttons for selecting what audio sources are heard by each member of the cockpit. It also includes a button for forcing the integrated cockpit into its fail-safe reversionary mode.

[edit] GMC/GCU Remote Controllers

The GMC and GCU controllers are panel-mounted modules which provide a more intuitive interface for the pilot than that provided by the GDU. The GMC controls the G1000's autopilot, while the GCU is used to enter navigational data and control the GDU's functions.

[edit] GIA Integrated Avionics Unit

The GIA unit is a combined communications and navigation radio, and also serves as the primary data aggregator for the G1000 system. It provides a two-way VHF communications transceiver, a VHF navigation receiver with glideslope, a GPS receiver, and a variety of supporting processors. Each unit is paired with a GDU display, which acts as a controlling unit. The GIA 63W, found on many newer G1000 installations, is an updated version of the older GIA 63 which includes Wide Area Augmentation System support.

[edit] GDC Air Data Computer

The GDC computer replaces the internal components of the pitot-static system in traditional aircraft instrumentation. It measures airspeed, altitude, vertical speed, and outside air temperature. This data is then provided to all the displays and integrated avionics units.

[edit] GRS Attitude and Heading Reference System (AHRS)

The GRS system uses solid-state sensors to measure aircraft attitude, rate of turn, and slip and skid. This data is then provided to all the integrated avionics units and GDU display units. Unlike many competing systems, the AHRS can be rebooted and recalibrated in flight during turns of up to 20 degrees.

[edit] GMU Magnetometer

The GMU magnetometer measures aircraft heading and is a digital version of a traditional compass. It does so through aligning itself with the magnetic flux lines of the earth.

[edit] GTX Transponder

Either the GTX 32 or GTX 33 transponder can be used in the G1000 system, although the GTX 33 is far more common. The GTX 32 provides standard mode-C replies to ATC interrogations while the GTX 33 provides mode-S bidirectional communications with ATC and therefore can indicate traffic in the area as well as announce itself spontaneously via "squitting" without prior interrogation.

[edit] GEA Engine/Airframe Unit

The GEA unit measures a large variety of engine and airframe parameters, including engine RPM, manifold pressure, oil temperature, cylinder head temperature, exhaust gas temperature, and fuel level in each tank. This data is then provided to the integrated avionics units.

[edit] GSD Data Aggregator

The GSD is a data aggregator system included on complex G1000 systems, such as that found on the Embraer Phenom 100. It serves as a point of connection which allows external systems to communicate with the G1000.

[edit] Backup systems

As a condition of certification, all aircraft utilizing the G1000 integrated cockpit must have a redundant airspeed indicator, altimeter, attitude indicator, and magnetic compass. In the event of a failure of the G1000 instrumentation, these backup instruments become primary.

In addition, a secondary power source is required to power the G1000 instrumentation for a limited time in the event of a failure of the aircraft's alternator and primary battery.

[edit] Certification

The Garmin G1000 is generally certified only on new general aviation aircraft, including Beechcraft, Cessna, Diamond, Cirrus Design, Mooney, Piper and Tiger. Garmin recently announced its first G1000 retrofit program for the Beechcraft King Air C90 beginning in Spring 2007. The Garmin G1000 became a jet platform in 2007, as the avionics system for the Cessna Citation Mustang Very Light Jet.[1] Versions of the G1000 are also used in the Embraer Phenom 100 and Embraer Phenom 300, as well as the HondaJet and King Air C90.

[edit] Competition

The G1000 competes with the Avidyne Entegra and Chelton FlightLogic EFIS glass cockpits. However, there are significant differences with regard to the features, degree of integration, intuitive aspects of the design, and overall product utility. Note that the Chelton system is not typically found in airplanes that include the less expensive G1000 or Avidyne systems.

[edit] Advantages and drawbacks

As the system has the GPS, communication, and radio navigation components built directly into the system, it both consolidates components into a centralized location and, for the same reason, becomes potentially more costly to repair or replace. The system has the potential to reduce downtime as key components, such as the AHRS, ADC and PFD, are modular and easily replaced. The system's design also prevents the failure of a single component from "cascading" through other components.

There are some safety concerns with all glass cockpits, such as the failure of the primary flight displays (PFD). These concerns, however, are no more (and perhaps are less) significant than similar considerations with aircraft equipped with traditional instrumentation^{[citation needed]}. The Garmin G1000 system offers a reversionary mode that will present all of the primary flight instrumentation on the remaining display. In addition, there are multiple GPS units, and electronic redundancy incorporated extensively throughout the design of the system. This built-in redundancy greatly improves safety over that of traditional instruments or single PFD systems.

There is a learning curve when transitioning to any technologically advanced cockpit and new users should focus on the differences in reading tape-style airspeed, altitude and vertical speed information.

Another important risk factor is the potential to spend too much time looking inside the cockpit managing the instrumentation, possibly increasing the chance of a collision with other aircraft, obstacles, or terrain. A flight instructor who is experienced with glass cockpits should help those transitioning to learn to balance the new workload. Once mastered, the richness of additional information available to the pilot makes a glass cockpit equipped aircraft arguably safer to fly, due to the surplus of available data and the manner in which it is presented.

[edit] Training resources

Flying any glass cockpit aircraft requires transition training to familiarize the pilot with the aircraft's systems. Transition training is most effective when a pilot prepares ahead of time. Most general aviation manufacturers using the G1000 system have FAA Industry Training Standards (FITS) training programs for pilots transitioning into their airplanes. FAA FITS compliant training is recommended for any pilot transitioning to the G1000 or any other glass cockpit prior to operating the aircraft in instrument meteorological conditions (IMC).

One of the most effective resources for preparing for G1000 transition training include the Garmin simulator software [2]. In addition, some flight schools now have G1000 flight training devices (FTDs) that provide realistic simulation.

All of the most current Garmin G1000 Pilot's Guides are available in PDF format for free downloading from Garmin.

Aviation History

History

Main article: Aviation history

“	Heavier-than-air flying machines are impossible.[1]	”
	— Lord Kelvin, 1892

Many cultures have built devices that travel through the air, from the earliest projectiles such as stones and spears, to more sophisticated buoyant or aerodynamic devices such as the mechanical pigeon of Archytas in Ancient Greece^[2][3], the boomerang in Australia, the hot air Kongming lantern, and kites. There are early legends of human flight such as the story of Icarus, and later, more credible claims of short-distance human flights including a kite flight by Yuan Huangtou in China, and the parachute, possibly flexible-winged, flight of Abbas Ibn Firnas (Armen Firman).

The modern age of aviation began with the first untethered human lighter-than-air flight on November 21, 1783, in a hot air balloon designed by the Montgolfier brothers.

The practicality of balloons was limited because they could only travel downwind. It was immediately recognized that a steerable, or dirigible, balloon was required. Jean-Pierre Blanchard flew the first human-powered dirigible in 1784 and crossed the English Channel in one in 1785. Subsequent early dirigible developments included machine-powered propulsion (Henri Giffard, 1852), rigid frames (David Schwarz, 1896), and improved speed and maneuverability (Alberto Santos-Dumont, 1901).

First flight by the Wright Brothers, December 17, 1903

Hindenburg at Lakehurst Naval Air Station, 1936

While there are many competing claims for the earliest powered, heavier-than-air flight, the most widely-accepted date is December 17, 1903 by the Wright brothers, though their 1903 aircraft was impractical to fly for more than a short distance because of control problems. Also, it didn't take off by itself, but required strong winds and a catapult to be launched, which some point out to say it didn't really fly on its own. That wouldn't change until the 14 Bis, built by the Brazilian Alberto Santos Dumont, which flew and landed without a rail, catapult, or the presence of high winds, propelled by its own (internal combustion) engine in October 23, 1906. The widespread adoption of ailerons made aircraft much easier to manage, and only a decade later, at the start of World War I, heavier-than-air powered aircraft had become practical for reconnaissance, artillery spotting, and even attacks against ground positions.

Aircraft began to transport people and cargo as designs grew larger and more reliable. In contrast to small non-rigid blimps, giant rigid airships became the first aircraft to transport passengers and cargo over great distances. The best known aircraft of this type were manufactured by the German Zeppelin company.

The most successful Zeppelin was the Graf Zeppelin. It flew over one million miles, including an around-the-world flight in August 1929. However, the dominance of the Zeppelins over the airplanes of the that period, which had a range of only a few hundred miles, was diminishing as airplane design advanced. The "Golden Age" of the airships ended on June 6, 1937 when the Hindenburg caught fire killing 36 people. Although there have been periodic initiatives to revive their use, airships have seen only niche application since that time.

Great progress was made in the field of aviation during the 1920s and 1930s, such as Charles Lindbergh's transatlantic flight in 1927, and Charles Kingsford Smith's transpacific flight the following year. One of the most successful designs of this period was the Douglas DC-3 which became the first airliner that was profitable carrying passengers exclusively, starting the modern era of passenger airline service. By the beginning of World War II, many towns and cities had built airports, and there were numerous qualified pilots available. The war brought many innovations to aviation, including the first jet aircraft and the first liquid-fueled rockets.

NASA's Helios researches solar powered flight.

After WW II, especially in North America, there was a boom in general aviation, both private and commercial, as thousands of pilots were released from military service and many inexpensive war-surplus transport and training aircraft became available. Manufacturers such as Cessna, Piper, and Beechcraft expanded production to provide light aircraft for the new middle class market.

By the 1950s, the development of civil jets grew, beginning with the de Havilland Comet, though the first widely-used passenger jet was the Boeing 707, because it was much more economical than other planes at the time. At the same time, turboprop propulsion began to appear for smaller commuter planes, making it possible to serve small-volume routes in a much wider range of weather conditions.

Yuri Gagarin was the first human to travel to space on April 12, 1961, while Neil Armstrong was the first to set foot on the moon on July 21, 1969.

Since the 1960s, composite airframes and quieter, more efficient engines have become available, and the Concorde provided supersonic passenger service for a time, but the most important lasting innovations have taken place in instrumentation and control. The arrival of solid-state electronics, the Global Positioning System, satellite communications, and increasingly small and powerful computers and LED displays, have dramatically changed the cockpits of airliners and, increasingly, of smaller aircraft as well. Pilots can navigate much more accurately and view terrain, obstructions, and other nearby aircraft on a map or through synthetic vision, even at night or in low visibility.

On June 21, 2004, SpaceShipOne became the first privately funded aircraft to make a spaceflight, opening the possibility of an aviation market outside the earth's atmosphere. Meanwhile, flying prototypes of aircraft powered by alternative fuels, such as ethanol, electricity, and even solar energy, are becoming more common and may soon enter the mainstream, at least for light aircraft.

[edit] Civil aviation

Main article: Civil aviation

Civil aviation includes all non-military flying, both general aviation and scheduled air transport.

[edit] Air transport

Main article: Airline

Swiss International Air Lines Airbus A330

There are five major manufacturers of civil transport aircraft (in alphabetical order):

• Airbus, based in France
• Boeing, based in the United States
• Bombardier, based in Canada
• Embraer, based in Brazil
• Tupolev, based in Russia (scheduled to be merged into the United Aircraft Building Corporation)

Boeing, Airbus, and Tupolev concentrate on wide-body and narrow-body jet airliners, while Bombardier and Embraer concentrate on regional airliners. Large networks of specialized parts suppliers from around the world support these manufacturers, who sometimes provide only the initial design and final assembly in their own plants. The Chinese ACAC consortium will also soon enter the civil transport market with its ACAC ARJ21 regional jet.^[4]

Until the 1970s, most major airlines were flag carriers, sponsored by their governments and heavily protected from competition. Since then, open skies agreements have resulted in increased competition and choice for consumers, coupled with falling prices for airlines. The combination of high fuel prices, low fares, high salaries, and crises such as the September 11, 2001 attacks and the SARS epidemic have driven many older airlines to government-bailouts, bankruptcy or mergers. At the same time, low-cost carriers such as Ryanair and Southwest have flourished.

[edit] General aviation

Main article: General aviation

1947 Cessna 120

A weight-shift ultralight aircraft, the Air Creation Tanarg

General aviation includes all non-scheduled civil flying, both private and commercial. General aviation may include business flights, air charter, private aviation, flight training, ballooning, parachuting, gliding, hang gliding, aerial photography, foot-launched powered hang gliders, air ambulance, crop dusting, charter flights, traffic reporting, police air patrols and forest fire fighting.

Each country regulates aviation differently, but general aviation usually falls under different regulations depending on whether it is private or commercial and on the type of equipment involved.

Many small aircraft manufacturers, including Cessna, Piper, Diamond, Mooney, Cirrus Design, Raytheon and others serve the general aviation market, with a focus on private aviation and flight training.

The most important recent developments for small aircraft (which form the bulk of the GA fleet) have been the introduction of advanced avionics (including GPS) that were formerly found only in large airliners, and the introduction of composite materials to make small aircraft lighter and faster. Ultralight and homebuilt aircraft have also become increasingly popular for recreational use, since in most countries that allow private aviation, they are much less expensive and less heavily regulated than certified aircraft.

[edit] Military aviation

Main article: Aerial warfare

Simple balloons were used as surveillance aircraft as early as the 18th century. Over the years, military aircraft have been built to meet ever increasing capability requirements. Manufacturers of military aircraft compete for contracts to supply their government's arsenal. Aircraft are selected based on factors like cost, performance, and the speed of production.

The Lockheed SR-71 remains unsurpassed in many areas of performance.

[edit] Types of military aircraft

• Fighter aircraft's primary function is to destroy other aircraft. (e.g. Sopwith Camel, A6M Zero, F-15, MiG-29, Su-27, F-22).
• Ground attack aircraft are used against tactical earth-bound targets. (e.g. Junkers Stuka diver bomber, A-10 Warthog, Ilyushin Il-2, J-22 Orao, and Sukhoi Su-25).
• Bombers are generally used against more strategic targets, such as factories and oil fields. (e.g. Zeppelin, B-29 Superfortress, Tu-95, Dassault Mirage IV, and the B-52 Stratofortress)
• Cargo transport aircraft are used to transport hardware and personnel, such as the C-17 Globemaster III or C-130 Hercules.
• Surveillance aircraft are used for reconnaissance (e.g. Rumpler Taube, de Havilland Mosquito, U-2, and MiG-25R).
• Helicopters are used for assault support, cargo transport and close air support (e.g.AH-64,Mi-24).

[edit] Air Traffic Control (ATC)

Main article: Air traffic control

Air traffic control towers at Schiphol Airport, the Netherlands

Air traffic control (ATC) involves communication with aircraft to help maintain separation — that is, they ensure that aircraft are sufficiently far enough apart horizontally or vertically for no risk of collision. Controllers may co-ordinate position reports provided by pilots, or in high traffic areas (such as the United States) they may use radar to see aircraft positions.

There are generally four different types of ATC:

• center controllers, who control aircraft en route between airports
• control towers (including tower, ground control, clearance delivery, and other services), which control aircraft within a small distance (typically 10-15 km horizontal, and 1,000 m vertical) of an airport.
• oceanic controllers, who control aircraft over international waters between continents, generally without radar service.
• terminal controllers, who control aircraft in a wider area (typically 50-80 km) around busy airports.

ATC is especially important for aircraft flying under Instrument flight rules (IFR), where they may be in weather conditions that do not allow the pilots to see other aircraft. However, in very high-traffic areas, especially near major airports, aircraft flying under Visual flight rules (VFR) are also required to follow instructions from ATC.

In addition to separation from other aircraft, ATC may provide weather advisories, terrain separation, navigation assistance, and other services to pilots, depending on their workload.

ATC do not control all flights. The majority of VFR flights in North America are not required to talk to ATC (unless they are passing through a busy terminal area or using a major airport), and in many areas, such as northern Canada, ATC services are not available even for IFR flights at lower altitudes.

[edit] Environmental impact

Main article: Aviation and the environment

Like all activities involving combustion, operating powered aircraft (from airliners to hot air balloons) releases greenhouse gases such as carbon dioxide (CO₂), soot, and other pollutants into the atmosphere. In addition, there are environmental impacts specific to aviation:

Water vapor contrails left by high-altitude jet airliners. These may contribute to cirrus cloud formation.

• Aircraft operating at high altitudes near the tropopause (mainly large jet airliners) emit aerosols and leave contrails, both of which can increase cirrus cloud formation — cloud cover may have increased by up to 0.2% since the birth of aviation.^[5]
• Aircraft operating at high altitudes near the tropopause can also release chemicals that interact with greenhouse gases at those altitudes, particularly nitrogen compounds, which interact with ozone, increasing ozone concentrations.^[6][7]
• Most light piston aircraft burn avgas, which contains tetra-ethyl lead (TEL), a highly-toxic substance that can cause soil contamination at airports. Some lower-compression piston engines can operate on unleaded mogas, and turbine engines and diesel engines — neither of which requires lead — are appearing on some newer light aircraft.