Machine Design Project Number 1 A Literature Study/Investigationfacultypages.ecc.edu/zadeh/ME290-291(317-318)-Machi… ·  · 2016-02-29Machine Design Project Number 1 A Literature

Machine Design Project Number 1

A Literature Study/Investigation

Crash of Flight 3407 in Clarence

Suggested Subjects:

1- What and how did it happen? Study the Details.

2- Study the theory and science behind the event. Make sure you have

studied all of the related subjects.

3- Could it be avoided? How? Give your suggested details.

4- Learn more about all of the parties involved, and their detail work

including:

a) Operators, their errors & shortcomings

b) Shortcomings of design engineers and the manufacturing company,

type of the engine, power of engines, design flaws, manufacturing

shortcomings, material related issues, operating conditions, wrong

applications, inherent flaw with propeller airplanes due to angular

momentum induced by the propeller, etc.

c) Subcontractors & their errors / shortcomings.

d) Main contractor (carrier) errors & faulty decisions.

5- Criticism (the blame game)

a) Think of responsibilities of each party

b) Give each party a numerical grade (0%-100%) for their

shortcomings/errors/mistakes. The more shortcomings should

correspond to a larger number. The summation of percentages

should add up to 100%.

6- Can better engineering help? How? Explain your suggestions in detail.

7- Write a clear teamwork report with all of references for your findings

and explain what happened, all of the scientific/engineering

background materials, if the failure could be avoided and a detailed

blame game.

Theory & Background Materials:

Understanding Lift & Drag

Lift is the force that will keep the airplane in the air and it is dependent on the geometry

of wing, speed, and the angle of attack (climb angle). It opposes the gravitational force of

airplane.

Drag is the resistance force of air to stop the airplane. It is dependent on the geometry of

wing, speed, and the angle of attack (climb angle). This force should get overcome by the

thrust of engine which pushes forward.

http://www.real-world-physics-problems.com/how-airplanes-fly.html

Maneuvering And Navigation

Airplanes control their navigation path and attitude (orientation relative to the direction of air

flow) by adjusting physical elements on the outside of the airplane, elements which modify the

airflow pattern around the plane, causing the plane to adjust its attitude and flight path. These

physical elements are called control surfaces and consist of ailerons, elevators, rudders, spoilers,

flaps, and slats. The Wikipedia page has a good explanation of this. Adjusting a plane's flight

path always involves either pitching, rolling, or yawing, or a combination of these. The figure

below illustrates what these are.

Effect of icing on the Lift and Drag

http://www.rdcollins.com.au/FAQRetrieve.aspx?ID=37143

Frequently Asked Questions

Question

Ice, Frost and Snow - What is the effect on an aircraft?

Answer

Even a small amount of ice, snow of frost on a wing can significantly reduce lift by up to 30 % in some cases, increase drag by up to 40 % in some cases, and increases aircraft weight. It alters the performance characteristics of the wing and may significantly increase the speed associated with an aerodynamic stall.

It is essential that all ice, frost and snow is removed from the wings and if possible, the tailplane before flight. Many accidents involving large and small aircraft have crashed as a direct result of ice, frost and or snow accumulation. I remember flying a Beechcraft Baron as a charter pilot about 25 or 30 years ago, and had to overnight in Armidale in winter. Next morning, although the day was clear, the frost was like snow. The aircraft wings and other surfaces were coated in a heavy layer of frost. I found the only container which would hold water (a garbage bin) and proceeded wash down the wings and tailplane to remove the frost. It was so cold that the washing water froze on the wings almost as fast as the frost was removed. The customer was not happy because he wanted to get going, and it was only frost – what’s the problem? I continued to wash down the wings and explained to him the consequences of not

doing so. He still was not completely happy, but I was, and, as far as I was concerned, in this case, it was all that mattered! This is one of those things that you have to be assertive about.

http://www.skybrary.aero/index.php/Aerodynamic_Effects_of_In-Flight_Icing

The aerodynamic effects of accreted ice on the continued safe flight of an aircraft are a

complex subject because of the many forms that such ice accretion can take. In certain

circumstances, very little surface roughness is required to generate significant

aerodynamic effects; as ice-load accumulates, there is often no aerodynamic warning of a

departure from normal performance. Stall warning systems are designed to operate in

relation to the angle of attack on a clean aeroplane and cannot be relied upon to activate

usefully in the case of an ice-loaded airframe.

http://icing.ae.illinois.edu/papers/05/Iced%20Airfoil%20Aerodynamics.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090005992.pdf

http://enu.kz/repository/2010/AIAA-2010-1237.pdf

Colgan Air Flight 3407

From Wikipedia, the free encyclopedia

A Dash-8 Q400 similar to the aircraft involved.

Accident summary

Date February 12, 2009

Summary Entered low-altitude stall, crashed into house

Site Clarence Center, New York, United States

Passengers 45

Crew 4

Injuries (non-fatal) 4 (all on the ground)

Fatalities 50 (one on the ground)

Survivors 0

Aircraft type Bombardier DHC8-402 Q400

Operator Colgan Air

as Continental Connection Registration

N200WQ

Flight origin Newark Liberty International Airport, Newark, New Jersey

Destination Buffalo Niagara International Airport, Buffalo, New York

Flight

From Wikipedia, the free encyclopedia

Colgan Air Flight 3407, marketed as Continental Connection under a codeshare

agreement with Continental Airlines, was a scheduled passenger flight from Newark,

New Jersey to Buffalo, New York, which crashed on February 12, 2009. The aircraft, a

Bombardier Dash-8 Q400, entered an aerodynamic stall from which it did not recover

and crashed into a house in Clarence Center, New York at 10:17 p.m. EST (03:17 UTC),

killing all 49 passengers, aircrew and cabin crew as well as one person inside the house.[1]

in April 2008[5] and entered service later that month.[6]

By MATTHEW L. WALD and LIZ ROBBINSFEB. 13, 2009

Colgan, the operator of the plane, also flies feeder routes for US Airways and United

Airlines. Colgan’s Web site said the airline operates about 50 aircraft, including 15 of the

Q400 model, and recently reached an agreement with Continental to add 15 more aircraft.

Colgan, which has flown for Continental since 1997, is owned by Pinnacle Airlines

Corporation, based in Memphis. Pinnacle has about 6,000 employees around North

America, 1,800 of them in Memphis.

Airplane (Bombardier DHC-8-400, N200WQ, operated by Colgan Air, Inc.):

From Wikipedia, the free encyclopedia

Dash 8 Q-Series

Flybe Q400

Role Turboprop airliner

Manufacturer de Havilland Canada, Bombardier Aerospace

First flight June 20, 1983

Introduction 1984 with NorOntair

Status In production, in service

Primary users Jazz, Horizon Air, Flybe, QantasLink

Horizon Air

Flybe

QantasLink

Produced 1983–present

Number built 1179 (as of December 31, 2015)[1]

Unit cost Q400 US$35 million[2]

Developed from de Havilland Canada Dash 7

The Q400 model has been involved in 13 incidents, but the crash of Flight 3407 was the

first resulting in fatalities.[6] This crash was the first fatality on a Colgan Air passenger

flight since the company was founded in 1991; there was a previous fatal accident (not

involving passengers) in August 2003 when a repositioning flight crashed offshore of

Massachusetts, killing both crew members. The only prior aviation incident on a Colgan

Air passenger flight occurred at LaGuardia Airport, when another plane collided with the

Colgan aircraft while taxiing, resulting in minor injuries to a flight attendant.[7]

Q400 is the stretched and improved 70–78 passenger version that entered service in 2000.

Its 360 knot (667 km/h) cruise speed is 60–90 knots (111–166 km/h) higher than its

competitors/predecessors. Powered by PW150A engines rated at 5,071 shp (3,781 kW) at

maximum power (4,850 shp or 3,620 kW maximum continuous rated). The maximum

operating altitude is 25,000 ft (7,600 m) for the standard version, although a version with

drop-down oxygen masks is offered, which increases maximum operating altitude to

27,000 ft (8,200 m). All Q400s include the ANVS system.

Series 400[66]

Unit cost (US$) $27 million

Entered service 2000

Typical passenger seating 78 (Single Class)

Passenger seating range 68–86[27]

Aircraft dimensions

Overall length 107 ft 8 in (32.81 m)

Height (to top of horizontal tail) 27 ft 3 in (8.3 m)

Fuselage diameter

Maximum cabin width

Cabin length 61 ft 8 in (18.8 m)

Wingspan (geometric) 93 ft 2 in (28.4 m)

Wing area (reference) 679.20 ft² (63.1 m²)

Basic operating data

Cockpit Crew

Cabin Crew 2–3

Engines 2 PW150A

Typical cruise speed 414 mph (667 km/h) 360 knots

Maximum operating altitude 27,000 ft (8,230 m)

Range (w/typical pax) 1,362 nautical miles (1,567 statute miles / 2,522 km)

Range (w/LR tanks) n/a

Takeoff run at MTOW 4,600 ft (1,402 m)

Design weights

Maximum takeoff weight 64,500 lb (29,260 kg)

Maximum landing weight 61,750 lb (28,010 kg)

Maximum zero fuel weight 57,000 lb (25,850 kg)

Maximum fuel capacity 1,748 US gal (6,616 L)

Typical operating weight empty 37,886 lb (17,185 kg)

Typical payload weight 19,114 lb (8,670 kg)

Flight Crew

From Wikipedia, the free encyclopedia

The Colgan flight crew consisted of pilot in command (captain) Marvin Renslow, 47, of

Lutz, Florida; first officer Rebecca Lynne Shaw, 24, of Maple Valley, Washington;[8][9][10]

and flight attendants Matilda Quintero and Donna Prisco. The captain was hired in

September 2005 and had accumulated 3,379 total flight hours, with 111 hours as captain

on the Q400. The first officer was hired in January 2008, and had 2,244 hours, 774 of

them in turbine aircraft including the Q400 (in aviation vernacular, known as "time in

type").[11] Joseph Zuffoletto, an off-duty captain aboard Flight 3407, was hired by Colgan

in September 2005[12][13] and regularly flew out of nearby Chautauqua County-Jamestown

Airport.[14]

On March 25, 2009, NTSB investigators said that icing probably did not contribute

greatly to the accident.[56] On May 11, 2009, new information came out that Captain

Renslow had failed three "check rides",[57] including some at Gulfstream International in

its pay to fly program,[citation needed] and it was suggested[who?] that he may not have been

adequately trained to respond to the emergency that led to the airplane's fatal descent.[57]

Investigators also suspected crew fatigue as both pilots appear to have been at Newark

airport overnight and all day before the 9:18 pm departure.[58][2]:104 et seq. In response to

questioning from the NTSB, Colgan Air officials acknowledged that both pilots

apparently were not paying close attention to the aircraft's instruments and unable to

follow the airline's procedures for handling an impending stall in the final minutes of the

flight. "I believe Capt. Renslow did have intentions of landing safely at Buffalo, as well

as first officer Shaw, but obviously in those last few moments ... the flight instruments

were not being monitored, and that's an indication of a lack of situational awareness,"

said John Barrett, Colgan's director of flight standards.[59] The official transcript of the

crew's communication, obtained from the cockpit voice recorder, as well as an animated

depiction of the crash, constructed using data from the flight data recorder were made

available to the public on May 12, 2009, the first day of the public hearing which was led

by the NTSB's then-chair Mark Rosenker.[citation needed] Some of the crew's communication

violated federal rules banning nonessential conversation.[60] From May 12 to 14, the

NTSB interviewed 20 witnesses of the flight.[61]

On June 3, 2009, the New York Times published an article[62] detailing complaints about

Colgan's operations from an FAA inspector who observed test flights in January 2008. As

in a previous FAA incident handling other inspectors' complaints,[62] the Colgan

inspector's complaints were deferred and the inspector was demoted. The incident is

under investigation by the Office of Special Counsel, the agency responsible for U.S.

Government federal whistle-blower complaints.

Safety issues examined during the accident investigation process included pilot training,

hiring, and fatigue problems, leading the FAA to issue a "Call to Action" for

improvements in the practices of regional carriers.[63]

By ALAN LEVIN, USA TODAY, WASHINGTON

Transcript: Pilots joked, talked shop before Buffalo crash

In the minutes before their commuter plane gyrated out of control near Buffalo, the pilots

of a Continental Connection flight joked and talked about work conditions — distractions

that were forbidden under federal law.

The cockpit recording released Tuesday by the National Transportation Safety Board

offers some of the first clues that could help explain why the pilots allowed the plane to

get too slow and then apparently tugged the plane into a sudden, fatal climb. It shows that

the pilots were perhaps inattentive during a critical phase of the flight as they prepared to

land. Other evidence released by the safety board suggests they may also have suffered

from lack of sleep and inadequate training. Capt. Marvin Renslow, 47, urged co-pilot

Rebecca Shaw, 24, who had complained that she was not feeling well, to pop her ears

seven minutes before the crash. "Yeah, I wanta make 'em pop," she replied, laughing,

according to the transcript of the sounds in the cockpit. Federal aviation regulations

forbid any non-work related conversation during an approach to landing.

The crash on Feb. 12 in Clarence Center, N.Y., killed all 49 people aboard the

flight and a man in a house struck by the plane — the first fatalities on a mid- or

large-size airline in nearly 2 ½ ears. The investigation has uncovered numerous

safety issues. The three-day hearing this week is expected to explore topics

ranging from whether the pilots were qualified to the airline's lack of training on

stall warning systems. According to NTSB documents:

Both pilots may not have gotten adequate rest before the flight. Shaw had taken

an overnight flight from Seattle before reporting to work. Renslow logged into an

airline computer system at 3 a.m. on the morning of the crash. Renslow had failed

four FAA check flights to determine whether he was qualified to fly. He also

failed an airline check. He was able to pass each of the checks after retaking the

test. Investigators found that pilots had not been trained how to use a safety

device that attempted to save the pilots as they went out of control. Known as a

"stick pusher," it automatically pushes a plane's nose down to pick up speed when

it gets dangerously slow. When it activated, Renslow overrode it, keeping the

nose pointed skyward.

Because of training issues such as this, it would be wrong to simply blame the

pilots for the crash, the union for the pilots said. The pilots were employed by

Colgan Air, which operated the flight for Continental. "I think there was some

element of surprise in this because they were never trained for it," said Capt. Paul

Rice, first vice president of the Air Line Pilots Association. Colgan issued a

statement saying that the pilots had been trained under a federally approved

program.

As they neared Buffalo on a snowy night, neither pilot realized that they had reduced the

power to a dangerously low setting, according to the recording and other data released by

the safety board. The plane lost 57 mph in less than 30 seconds, slowing well below the

airline's required minimum speed of 166 mph during icing conditions. What happened

next doomed the flight. The plane's "stick shaker" — the device that warns pilots when a

plane gets too slow — activated, violently vibrating the control column. Instead of adding

power and lowering the plane's nose as pilots are taught, Renslow pulled the plane into a

climb that slowed it even further. "Jesus Christ," he said. As Renslow struggled with the

controls, Shaw tried to help by resetting flaps on the plane's wings and retracting the

landing gear. "Gear up, oh (expletive)," she said. By this time, the plane's wings were no

longer keeping the plane aloft — known as an aerodynamic stall — and it was rolling

violently from side to side and plunging toward the ground. "We're down," Renslow said

in the final seconds before the recording ended. "We're…." The final sound on the

recording was a scream by Shaw, the NTSB reported.

Weather Condition

From Wikipedia, the free encyclopedia

The flight had been cleared for the instrument landing system approach to Buffalo

Niagara International Airport runway 23 when it disappeared from radar. Weather

conditions were a wintry mix in the area, with light snow, fog, and winds at 17 miles per

hour (15 knots). The de-icing system was turned on 11 minutes into the flight by the

crew, who discussed significant ice buildup on the aircraft's wings and windscreen

shortly before the crash.[15][16][17] Two other aircraft reported icing conditions around the

time of the crash. The last radio transmission from the flight occurred when the plane was

3.0 miles (4.8 km) northeast of the airport radio beacon known as KLUMP (see diagram),

when the first officer acknowledged a routine instruction to change to tower frequency.

The aircraft crashed 41 seconds after the last transmission.

On February 15, more information on the crash was released by the NTSB saying it

appeared the plane had been on autopilot when it went down. The investigators did not

find evidence of the severe icing conditions that would have required the pilots to fly

manually.[50] Colgan recommends pilots fly manually in icing conditions, and requires

them to do so in severe icing conditions. The NTSB had issued a safety alert about the

use of autopilot in icing conditions in December 2008. Without flying manually, pilots

may be unable to feel changes in the handling characteristics of the airplane, which is a

warning sign of ice buildup. The NTSB also revealed that the plane crashed 26 seconds

after trouble was first registered on the flight data recorder.[51][52][53]

By MATTHEW L. WALD and LIZ ROBBINSFEB. 13, 2009

AMHERST, N.Y. -- The crew of the plane that crashed near Buffalo on Thursday night

discussed a “significant ice buildup” on the wings and windshield as the aircraft

descended through light snow and mist, according to the flight data and voice recordings

recovered from the scene of the accident that killed all 49 people on board and one person

on the ground.

In the final minute of the flight from Newark Liberty International Aiport, Mr.

Chealander said the pilots apparently tried to abort the landing, but the plane violently

pitched and rolled and seconds later crashed into a house in Clarence Center, N.Y., a

Buffalo suburb six miles from the airport.

“The crew commented at 16,000 feet that they noticed it was rather hazy and

requested to descend to 12,000 feet, and shortly after that request, they were cleared

to 11,000,” he said. “Around that time, the crew discussed significant ice buildup, on

the windshield and leading edge of the wings.”

He said that the de-icing system had already been in the on-position when the crew

discussed the ice on the plane. The plane continued its descent, and the crew lowered the

landing gear with a minute left on the tape.

Forty seconds later, the pilots extended the flaps, the moveable panels on the rear edge of

the wings that allow a plane to maintain lift as it slows. But within seconds of extending

the flaps, the plane experienced “severe pitch and roll excursions,” meaning that the nose

pointed up and down and the wings wagged from side to side, said Mr. Chealander.

“After that,” he said, “the crew attempted to raise the gear and flaps just before the end of

the recording.”

Mr. Chealander, a former airline captain, emphasized that the board was in a “fact-

gathering stage” and would not analyze the data now. However, the sequence he

described is consistent with previous crashes caused by icing.

There is no indication so far that the weather was unusual for Buffalo in February.

Visibility around the airport was three miles, with snow and mist. “That’s icing

conditions,” Mr. Chealander said.

Anti-Icing System:

By MATTHEW L. WALD and LIZ ROBBINSFEB. 13, 2009

The airplane, a Bombardier Dash 8 Q400 with two turboprop engines and room for 74

passengers, is certified for flight into “known icing conditions.” But when the pilots

change the shape of the wings, by moving the flaps or other controls, sometimes buildups

of ice that were not a factor in an earlier configuration are suddenly exposed to the

passing wind and make the plane uncontrollable.

The flight data recorder was unusually comprehensive, measuring 250 different data

points at frequent intervals, including use of the anti-icing system, but it did not record

whether that system actually worked. On the Dash 8, a turboprop, the anti-icing

system consists mostly of rubber, tire-like pneumantic “boots,” said Mr.

Chealander. These “boots” inflate and shrink, breaking off accumulations of ice

from the forward edges of the wings.

Crash:

From Wikipedia, the free encyclopedia

During the flight and continuing through the plane's landing approach, the crew had been

flying on autopilot. During final approach, the pilots extended the aircraft's flaps and

landing gear for landing. After the landing gear and flaps had been extended, the flight

data recorder (FDR) indicated that the airspeed had decayed to 145 knots (269 km/h).[2]

The captain, who was the pilot flying, then called for the flaps to be set at the 15 degree

position. As the flaps transitioned past the 10 degree mark, the FDR indicated that the

airspeed had further slowed to 135 knots (250 km/h). Six seconds later, the aircraft's stick

shaker, a device intended to provide aural and tactile awareness of a low speed condition,

sounded. At that time, the cockpit voice recorder (CVR) recorded the autopilot

disengaging. The FDR now indicated that the aircraft's speed was a dangerously slow 131

knots (243 km/h). Instead of following the established stall recovery procedure of adding

full power and lowering the nose to prevent the imminent low-altitude stall, the captain

only added about 75% power and continued applying nose-up inputs. As the aircraft

came even closer to stalling the stick pusher activated ("The Q400 stick pusher applies an

airplane-nose-down control column input to decrease the wing angle-of-attack [AOA]

after an aerodynamic stall").[2] The captain overrode the stick pusher and continued

pulling on the control yoke which caused the aircraft upset and later loss of control; in

addition, the first officer retracted the flaps without consulting with the captain, making

recovery more difficult.[22] The aircraft went into a yaw and pitched up at an angle of 31

degrees in its final moments, before pitching down at 25 degrees. It then rolled to the left

at 46 degrees and snapped back to the right at 105 degrees. Occupants aboard

experienced forces estimated at nearly twice that of gravity.

The plane struggled for about 25 seconds, during which time the flight crew made no

emergency declaration. The Q400 rapidly lost altitude and crashed into a private home at

6038 Long Street,[23] about 5 miles (8.0 km) from the end of the runway, and nearly

directly under its intended approach path, with the nose pointed away from the

destination airport. The aircraft exploded on impact, destroying the house and most of the

plane, with the tail of the plane broken off and nearly intact. The house was the home of

Douglas and Karen Wielinski along with their daughter Jill. Douglas was killed; his wife

and daughter escaped with minor injuries and were treated at the Millard Fillmore

Hospital. The lots in the area are only 60 feet (18.3 meters) wide; the plane hit the house

squarely, destroying it in the ensuing fire with little damage to surrounding homes.[24] The

home was close to the Clarence Center Fire Company, so emergency personnel were able

to respond quickly. Two of the firefighters were injured. The crash and intense fire

caused the evacuation of 12 nearby houses.[4][16][21][25][26][27][28]

More details emerged on February 18. It was reported that a re-creation of events leading

up to the crash indicated that the stick pusher had activated, which pushes the nose down

when it determines a stall is imminent in order to maintain airspeed so the wings continue

to generate lift and keep the aircraft aloft. The crew, concerned about a nose-down

attitude so close to the ground, may have responded by pulling the nose upward and

increasing power, but over-corrected, causing a stall or even a spin.[54] Bill Voss, president

of Flight Safety Foundation, told USA Today that it sounded like the plane was in "a

deep stall situation".[55]

Victims:

From Wikipedia, the free encyclopedia

Nationality Passengers Crew Ground Total[29]

United States 41 4 1 46

Canada 2 0 0 2

China 1 0 0 1

Israel 1 0 0 1

Total 45 4 1 50

Data & Voice Recorders:

From Wikipedia, the free encyclopedia

The U.S. National Transportation Safety Board (NTSB) announced that they would send

a team to the crash site on February 13 to begin the investigation.[18][19] NTSB spokesman

Steve Chealander said that 14 investigators were assigned to the crash of Continental

Connection Flight 3407.[45] Both the flight data recorder (FDR) and the cockpit voice

recorder (CVR) were retrieved and analyzed in Washington, D.C.[21][46]

After initial analysis of the recordings, it was determined that the aircraft went through

severe pitch and roll oscillations after positioning its flaps and landing gear for landing.

Until that time, the aircraft had been maneuvering normally. The de-icing system was

reported to be turned on. During descent, the crew reported about 3 miles (4.8 km) of

visibility with snow and mist. Preceding the crash, the aircraft's stall-protection systems

had activated. Instead of the aircraft's diving straight into the house as was initially

thought, it was found that the aircraft fell 800 feet (240 m) before crashing pointing

northeast, away from the destination airport. The passengers were given no warning of

any trouble by the pilots. Occupants experienced an estimated force two times that of

gravity just before impact. Chealander said information from the aircraft's flight data

recorder indicates that the plane pitched up at an angle of 31 degrees, then down at 45

degrees. The aircraft rolled to the left at 46 degrees, then snapped back to the right at 105

degrees, before crashing into the house, and erupting in flames on impact.[16][21][27][47][48]

Final Report:

From Wikipedia, the free encyclopedia

On February 2, 2010, the NTSB issued its final report, describing its investigation,

findings, conclusions and recommendations. The report includes a "Conclusions" section

that summarizes the known facts and lists a variety of contributing factors relating to the

flight crew. According to the final report, the accident's probable cause "was the captain’s

inappropriate response to the activation of the stick shaker, which led to an aerodynamic

stall from which the airplane did not recover."[2]:155

The NTSB further added the following contributing factors: Contributing to the accident

were (1) the flight crew’s failure to monitor airspeed in relation to the rising position of

the low- speed cue, (2) the flight crew’s failure to adhere to sterile cockpit procedures, (3)

the captain’s failure to effectively manage the flight, and (4) Colgan Air’s inadequate

procedures for airspeed selection and management during approaches in icing conditions.

However, the NTSB was unable to determine why the first officer retracted the flaps and

suggested that the landing gear should be retracted. The method by which civil aircraft

pilots can obtain their licenses was also criticized by the NTSB. It also found that: "The

pilots' performance was likely impaired because of fatigue, but the extent of their

impairment and the degree to which it contributed to the performance deficiencies that

occurred during the flight cannot be conclusively determined." NTSB Chair Deborah

Hersman, while concurring, made it clear she considered fatigue a contributing factor.

She compared the twenty years that fatigue has remained on the NTSB's Most wanted list

of transportation safety improvements, without getting substantial action on the matter

from regulators, to the changes in tolerance for alcohol over the same time period, noting

that the performance impacts of fatigue and alcohol were similar.[2]:176-178

Stall

From Wikipedia, the free encyclopedia

In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle

of attack increases.[1]

This occurs when the critical angle of attack of the foil is exceeded.

The critical angle of attack is typically about 15 degrees, but it may vary significantly

depending on the fluid, foil, and Reynolds number.

Stalls in fixed-wing flight are often experienced as a sudden reduction in lift as the pilot

increases the wing's angle of attack and exceeds its critical angle of attack (which may be

due to slowing down below stall speed in level flight). A stall does not mean that the

engine(s) have stopped working, or that the aircraft has stopped moving — the effect is

the same even in an unpowered glider aircraft. Vectored thrust in manned and unmanned

aircraft is used to surpass the stall limit, thereby giving rise to post-stall technology.[2][3]

A stall is a condition in aerodynamics and aviation wherein the angle of attack increases

beyond a certain point such that the lift begins to decrease. The angle at which this occurs

is called the critical angle of attack. This critical angle is dependent upon the airfoil

section or profile of the wing, its planform, its aspect ratio, and other factors, but is

typically in the range of 8 to 20 degrees relative to the incoming wind for most subsonic

airfoils. The critical angle of attack is the angle of attack on the lift coefficient versus

angle-of-attack curve at which the maximum lift coefficient occurs.[citation needed]

Flow separation begins to occur at small angles of attack while attached flow over the

wing is still dominant. As angle of attack increases, the separated regions on the top of

the wing increase in size and hinder the wing's ability to create lift. At the critical angle

of attack, separated flow is so dominant that further increases in angle of attack produce

less lift and vastly more drag.[citation needed]

Dynamic stall

Dynamic stall is a non-linear unsteady aerodynamic effect that occurs when airfoils

rapidly change the angle of attack. The rapid change can cause a strong vortex to be shed

from the leading edge of the aerofoil, and travel backwards above the wing. [25] The

vortex, containing high-velocity airflows, briefly increases the lift produced by the wing.

As soon as it passes behind the trailing edge, however, the lift reduces dramatically, and

the wing is in normal stall.[26]

Dynamic stall is an effect most associated with helicopters and flapping wings. During

forward flight, some regions of a helicopter blade may incur flow that reverses (compared

to the direction of blade movement), and thus includes rapidly changing angles of attack.

Oscillating (flapping) wings, such as those of insects—including the most famous one,

the bumblebee—may rely almost entirely on dynamic stall for lift production, provided

the oscillations are fast compared to the speed of flight, and the angle of the wing

changes rapidly compared to airflow direction.[26]

Stall delay can occur on airfoils subject to a high angle of attack and a three-dimensional

flow. When the angle of attack on an airfoil is increasing rapidly, the flow will remain

substantially attached to the airfoil to a significantly higher angle of attack than can be

achieved in steady-state conditions. As a result, the stall is delayed momentarily and a lift

coefficient significantly higher than the steady-state maximum is achieved. The effect

was first noticed on propellers.[27]

Warning and safety devices

Fixed-wing aircraft can be equipped with devices to prevent or postpone a stall or to

make it less (or in some cases more) severe, or to make recovery easier.

An aerodynamic twist can be introduced to the wing with the leading edge near

the wing tip twisted downward. This is called washout and causes the wing root

to stall before the wing tip. This makes the stall gentle and progressive. Since the

stall is delayed at the wing tips, where the ailerons are, roll control is maintained

when the stall begins.

A stall strip is a small sharp-edged device that, when attached to the leading edge

of a wing, encourages the stall to start there in preference to any other location on

the wing. If attached close to the wing root, it makes the stall gentle and

progressive; if attached near the wing tip, it encourages the aircraft to drop a wing

when stalling.

A stall fence is a flat plate in the direction of the chord to stop separated flow

progressing out along the wing[56]

Vortex generators, tiny strips of metal or plastic placed on top of the wing near

the leading edge that protrude past the boundary layer into the free stream. As the

name implies, they energize the boundary layer by mixing free stream airflow

with boundary layer flow thereby creating vortices, this increases the momentum

in the boundary layer. By increasing the momentum of the boundary layer,

airflow separation and the resulting stall may be delayed.

An anti-stall strake is a leading edge extension that generates a vortex on the

wing upper surface to postpone the stall.

A stick pusher is a mechanical device that prevents the pilot from stalling an

aircraft. It pushes the elevator control forward as the stall is approached, causing a

reduction in the angle of attack. In generic terms, a stick pusher is known as a

stall identification device or stall identification system.[57]

A stick shaker is a mechanical device that shakes the pilot's controls to warn of

the onset of stall.

A stall warning is an electronic or mechanical device that sounds an audible

warning as the stall speed is approached. The majority of aircraft contain some

form of this device that warns the pilot of an impending stall. The simplest such

device is a stall warning horn, which consists of either a pressure sensor or a

movable metal tab that actuates a switch, and produces an audible warning in

response.

An angle-of-attack indicator for light aircraft, the "AlphaSystemsAOA" and a

nearly identical "Lift Reserve Indicator", are both pressure differential

instruments that display margin above stall and/or angle of attack on an

instantaneous, continuous readout. The General Technics CYA-100 displays true

angle of attack via a magnetically coupled vane. An AOA indicator provides a

visual display of the amount of available lift throughout its slow speed envelope

regardless of the many variables that act upon an aircraft. This indicator is

immediately responsive to changes in speed, angle of attack, and wind conditions,

and automatically compensates for aircraft weight, altitude, and temperature.

An angle of attack limiter or an "alpha" limiter is a flight computer that

automatically prevents pilot input from causing the plane to rise over the stall

angle. Some alpha limiters can be disabled by the pilot.

De-icing:

De-ice

From Wikipedia, the free encyclopedia

For snow and ice control on roadways and similar facilities, see Snow removal.

An Aeroflot Airbus A330 being de-iced at Sheremetyevo International Airport.

Spray de-icing at Salt Lake City airport, 2010

De-icing is defined as removal of snow, ice or frost from a surface. Anti-icing is

understood to be the application of chemicals that not only de-ice, but also remain on a

surface and continue to delay the reformation of ice for a certain period of time, or

prevent adhesion of ice to make mechanical removal easier.

Aircraft Applicatons for De-icing

1-On the Ground

On the ground, when there are freezing conditions and precipitation, de-icing an aircraft

is crucial. Frozen contaminants cause critical control surfaces to be rough and uneven,

disrupting smooth air flow and greatly degrading the ability of the wing to generate lift,

and increasing drag. This situation can cause a crash. If large pieces of ice separate when

the aircraft is in motion, they can be ingested in engines or hit propellers and cause

catastrophic failure. Frozen contaminants can jam control surfaces, preventing them from

moving properly. Because of this potentially severe consequence, de-icing is performed

at airports where temperatures are likely to be around 0 °C (32 °F).

In flight, droplets of supercooled water often exist in stratiform and cumulus clouds.

They form into ice when they are struck by the wings of passing airplanes and abruptly

crystallize. This disrupts airflow over the wing, reducing lift, so aircraft that are expected

to fly in such conditions are equipped with a de-icing system.

De-icing techniques are also employed to ensure that engine inlets and various sensors on

the outside of the aircraft are clear of ice or snow.

De-icing on the ground is usually done by spraying aircraft with a de-icing fluid based on

propylene glycol, similar to ethylene glycol antifreeze used in some automobile engine

coolants. Ethylene Glycol (EG) is still in use for aircraft de-icing in some parts of the

world because it has a lower operational use temperature (LOUT) than Propylene Glycol

(PG), but PG is more common because it is classified as non-toxic, unlike Ethylene

Glycol. Nevertheless, it still must be used with a containment system to capture the used

liquid, so that it cannot seep into the ground and water courses. Even though classified as

non-toxic, it has negative effects in nature, since it uses oxygen during breakdown,

causing aquatic life to suffocate. In one case, a significant snow in Atlanta in early

January 2002 caused an overflow of such a system, briefly contaminating the Flint River

downstream of the Atlanta airport. Many airports recycle used de-icing fluid, separating

water and solid contaminants, enabling reuse of the fluid in other applications.

Some more Details

De-icing can be accomplished by mechanical methods (scraping, pushing); through the

application of heat; by use of dry or liquid chemicals designed to lower the freezing point

of water (various salts or brines, alcohols, glycols); or by a combination of these different

techniques.

Anti-icing of aircraft is accomplished by applying a protective layer, using a viscous fluid

called anti-ice fluid, over a surface to absorb the contaminate. All anti-ice fluids offer

only limited protection, dependent upon frozen contaminant type and prevailing weather

conditions. A fluid has failed when it no longer can absorb the contaminant and it

essentially becomes a contaminant itself. Even water can be a contaminant in this sense,

as it dilutes the anti-icing agent until it is no longer effective.

De-icing of roads has traditionally been done with salt, spread by snowplows or dump

trucks designed to spread it, often mixed with sand and gravel, on slick roads. Sodium

chloride (rock salt) is normally used, as it is inexpensive and readily available in large

quantities. However, since salt water still freezes at −18 °C (0 °F), it is of no help when

the temperature falls below this point. It also has a strong tendency to cause corrosion,

rusting the steel used in most vehicles and the rebar in concrete bridges. Depending on

the concentration, it can be toxic to some plants and animals, and some urban areas have

moved away from it as a result. More recent snowmelters use other salts, such as calcium

chloride and magnesium chloride, which not only depress the freezing point of water to a

much lower temperature, but also produce an exothermic reaction. They are somewhat

safer for sidewalks, but excess should still be removed.

More recently, organic compounds have been developed that reduce the environmental

issues connected with salts and have longer residual effects when spread on roadways,

usually in conjunction with salt brines or solids. These compounds are generated as

byproducts of agricultural operations such as sugar beet refining or the distillation

process that produces ethanol.[1][2] Additionally, mixing common rock salt with some of

the organic compounds and magnesium chloride results in spreadable materials that are

both effective to much colder temperatures (−34 °C or −29 °F) as well as at lower overall

rates of spreading per unit area.[3]

Direct infrared heating has also been proposed for deicing purpose. This heat transfer

mechanism is substantially faster than conventional heat transfer modes used by

conventional deicing (convection and conduction) due to the cooling effect of the air on

the deicing fluid spray.

Solar road systems have been used to maintain the surface of roads above the freezing

point of water. An array of pipes embedded in the road surface is used to collect solar

energy in summer, transfer the heat to thermal banks and return the heat to the road in

winter to maintain the surface above 0 °C (32 °F).[4] This automated form of renewable

energy collection, storage and delivery avoids the environmental issues of using chemical

contaminants.

2-Pneumatic systems

B-17 Flying Fortress. The black strips on the leading edges of the tail, stabilizers and

wing are deicing boots made of rubber.

Inflight ice buildups are most frequent on the leading edges of the wings, tail and engines

(including the propellers or fan blades). Lower speed aircraft frequently use pneumatic

deicing boots on the leading edges of wings and tail for inflight de-icing. The rubber

coverings are periodically inflated, causing ice to crack and flake off. Once the system is

activated by the pilot, the inflation/deflation cycle is automatically controlled. In the past,

it was thought such systems can be defeated if they are inflated prematurely; if the pilot

did not allow a fairly thick layer of ice to form before inflating the boots, the boots would

merely create a gap between the leading edge and the formed ice. Recent research shows

“bridging” does not occur with modern boots.[9]

3-Electric systems

Some aircraft may also use electrically heated resistive elements embedded in a rubber

sheet cemented to the leading edges of wings and tail surfaces, propeller leading edges,

and helicopter rotor blade leading edges. This de-icing system was developed by United

States Rubber Company in 1943.[10] Such systems usually operate continuously. When ice

is detected, they first function as de-icing systems, then as anti-icing systems for

continued flight in icing conditions. Some aircraft use chemical de-icing systems which

pump antifreeze such as alcohol or propylene glycol through small holes in the wing

surfaces and at the roots of propeller blades, melting the ice, and making the surface

inhospitable to ice formation. A fourth system, developed by NASA, detects ice on the

surface by sensing a change in resonance frequency. Once an electronic control module

has determined that ice has formed, a large current spike is pumped into the transducers

to generate a sharp mechanical shock, cracking the ice layer and causing it to be peeled

off by the slipstream.

4-Air bleed systems

Many modern civil fixed-wing transport aircraft use anti-ice systems on the leading edge

of wings, engine inlets and air data probes using warm air. This is bled from engines and

is ducted into a cavity beneath the surface to be anti-iced. The warm air heats the surface

up to a few degrees above 0 °C (32 °F), preventing ice from forming. The system may

operate autonomously, switching on and off as the aircraft enters and leaves icing

conditions.

Some of Aircraft Engines

1-Turboprop

Cutaway view of a Garrett TPE-331 turboprop engine showing the gearbox at the front of

the engine

Main article: Turboprop

While military fighters require very high speeds, many civil airplanes do not. Yet, civil

aircraft designers wanted to benefit from the high power and low maintenance that a gas

turbine engine offered. Thus was born the idea to mate a turbine engine to a traditional

propeller. Because gas turbines optimally spin at high speed, a turboprop features a

gearbox to lower the speed of the shaft so that the propeller tips don't reach supersonic

speeds. Often the turbines that drive the propeller are separate from the rest of the

rotating components so that they can rotate at their own best speed (referred to as a free-

turbine engine). A turboprop is very efficient when operated within the realm of cruise

speeds it was designed for, which is typically 200 to 400 mph (320 to 640 km/h).

Jets

2-Turbojet

A General Electric J85-GE-17A turbojet engine. This cutaway clearly shows the 8 stages

of axial compressor at the front (left side of the picture), the combustion chambers in the

middle, and the two stages of turbines at the rear of the engine.

Main article: Turbojet

A turbojet is a type of gas turbine engine that was originally developed for military

fighters during World War II. A turbojet is the simplest of all aircraft gas turbines. It

consists of a compressor to draw air in and compress it, a combustion section where fuel

is added and ignited, one or more turbines that extract power from the expanding exhaust

gases to drive the compressor, and an exhaust nozzle that accelerates the exhaust gases

out the back of the engine to create thrust. When turbojets were introduced, the top speed

of fighter aircraft equipped with them was at least 100 miles per hour faster than

competing piston-driven aircraft. In the years after the war, the drawbacks of the turbojet

gradually became apparent. Below about Mach 2, turbojets are very fuel inefficient and

create tremendous amounts of noise. Early designs also respond very slowly to power

changes, a fact that killed many experienced pilots when they attempted the transition to

jets. These drawbacks eventually led to the downfall of the pure turbojet, and only a

handful of types are still in production. The last airliner that used turbojets was the

Concorde, whose Mach 2 airspeed permitted the engine to be highly efficient.

3-Turbofan

A cutaway of a CFM56-3 turbofan engine

Main article: Turbofan

A turbofan engine is much the same as a turbojet, but with an enlarged fan at the front

that provides thrust in much the same way as a ducted propeller, resulting in improved

fuel-efficiency. Though the fan creates thrust like a propeller, the surrounding duct frees

it from many of the restrictions that limit propeller performance. This operation is a more

efficient way to provide thrust than simply using the jet nozzle alone and turbofans are

more efficient than propellers in the trans-sonic range of aircraft speeds, and can operate

in the supersonic realm. A turbofan typically has extra turbine stages to turn the fan.

Turbofans were among the first engines to use multiple spools—concentric shafts that are

free to rotate at their own speed—to let the engine react more quickly to changing power

requirements. Turbofans are coarsely split into low-bypass and high-bypass categories.

Bypass air flows through the fan, but around the jet core, not mixing with fuel and

burning. The ratio of this air to the amount of air flowing through the engine core is the

bypass ratio. Low-bypass engines are preferred for military applications such as fighters

due to high thrust-to-weight ratio, while high-bypass engines are preferred for civil use

for good fuel efficiency and low noise. High-bypass turbofans are usually most efficient

when the aircraft is traveling at 500 to 550 miles per hour (800 to 885 km/h), the cruise

speed of most large airliners. Low-bypass turbofans can reach supersonic speeds, though

normally only when fitted with afterburners.

Engines of Flight Bombardier Q400 (2 PW150A)

Type Turboprop

National origin Canada

Manufacturer Pratt & Whitney Canada

The twin-engine turboprop Bombardier Dash 8 Q400, registered N200WQ, was

manufactured in 2008 for Colgan. N200WQ was registered with the Federal Aviation

Administration

PW150A was certified in 1998-06-24 with a maximum continuous rating of 5071 SHP

(3782kW),[1] although capable of up to 7000 SHP. Has a 3 stage axial low pressure

compressor instead of the centrifugal NL unit on other variants. Used on the Bombardier

Q400

A turboprop engine is a turbine engine that drives an aircraft propeller.[1] In contrast to a

turbojet, the engine's exhaust gases do not contain enough energy to create significant

thrust, since almost all of the engine's power is used to drive the propeller.

The propeller is coupled to the turbine through a reduction gear that converts the high

RPM, low torque output to low RPM, high torque. The propeller itself is normally a

constant speed (variable pitch) type similar to that used with larger reciprocating aircraft

engines.[citation needed]

Turboprop engines are generally used on small subsonic aircraft, but some aircraft

outfitted with turboprops have cruising speeds in excess of 500 kt (926 km/h,

575 mph).[citation needed] Large military and civil aircraft, such as the Lockheed L-188 Electra

and the Tupolev Tu-95, have also used turboprop power. The Airbus A400M is powered

by four Europrop TP400 engines, which are the third most powerful turboprop engines

ever produced, after the Kuznetsov NK-12 and Progress D-27.[citation needed]

In its simplest form a turboprop consists of an intake, compressor, combustor, turbine,

and a propelling nozzle. Air is drawn into the intake and compressed by the compressor.

Fuel is then added to the compressed air in the combustor, where the fuel-air mixture then

combusts. The hot combustion gases expand through the turbine. Some of the power

generated by the turbine is used to drive the compressor. The rest is transmitted through

the reduction gearing to the propeller. Further expansion of the gases occurs in the

propelling nozzle, where the gases exhaust to atmospheric pressure. The propelling

nozzle provides a relatively small proportion of the thrust generated by a turboprop.

Turboprops are most efficient at flight speeds below 725 km/h (450 mph; 390 knots)

because the jet velocity of the propeller (and exhaust) is relatively low. Due to the high

price of turboprop engines, they are mostly used where high-performance short-takeoff

and landing (STOL) capability and efficiency at modest flight speeds are required. The

most common application of turboprop engines in civilian aviation is in small commuter

aircraft, where their greater power and reliability than reciprocating engines offsets their

higher initial cost and fuel consumption. Turboprop airliners now operate at near the

same speed as small turbofan-powered aircraft but burn two-thirds of the fuel per

passenger.[2] However, compared to a turbojet (which can fly at high altitude for enhanced

speed and fuel efficiency) a propeller aircraft has a much lower ceiling. Turboprop-

powered aircraft have become popular for bush airplanes such as the Cessna Caravan and

Quest Kodiak as jet fuel is easier to obtain in remote areas than is aviation-grade gasoline

(avgas).[citation needed]

Comparison http://www.theatlantic.com/technology/archive/2011/12/a-single-boeing-777-engine-

delivers-twice-the-horsepower-of-all-the-titanics/250698/

A Single Boeing 777 Engine Delivers Twice the

Horsepower of All the Titanic's

The RMS Titanic weighed almost 50,000 tons and could carry 3,500 people.

Before it sunk, it was world-famous as the massive titan of the sea. Its multiple

engines, powered by 159 coal furnaces, were designed to deliver 46,000

horsepower.

Compare that to today's beastly mode of transport: the Boeing 777. Bangalore

Aviation points out that a single GE90-115B engine puts out over 110,000

horsepower, or more than twice the design output of all the Titanic's steam

engines.

And that power is obviously hooked up to a much smaller vehicle. The Titanic

had to carry 14,000,000 pounds of coal alone; the 777 has a total weight of only

775,000 pounds.

Just something to contemplate as you fly back to or from home for the

holidays.

Commenter Rogerone0 makes this excellent point in the comments. When it

comes to exerting power, horsepower isn't all there is to it.

If you could put the Titanic in Boston Harbor about a 1/2 mile south of Logan

airport and you placed a 777 on the runway and then connected the two by a

superstrong/super light cable. Then you told the 777 to put both engines at full

throttle the cable would flatten but the titanic wouldn't perceptibly begin to

move. Then after 10 seconds or so you tell the titanic to go forward slow or

1/8th forward. The Titanic would then slowly pull the 777 off the end of the

runway in about three minutes. The comparison of power would not even be

close.

Why? Steam engines have very high force multipliers (think Newton) and jets

have very low force multipliers. Another better way to look at this is to

compare torque. Steam is around x300 and jets are around x0.33. Internal gas

engines are around x1. This is why at county/farm tractor pulls old 1910s steam

engine tractors with 15 hp always beat 1970s gas engine tractors with 500 hp.

https://www.quora.com/What-cancels-the-angular-momentum-of-the-propeller-on-

a-single-prop-airplane

What cancels the angular momentum of the

propeller on a single prop airplane?