fat bird hath a fall part 1 v-if

8/4/2019 Fat Bird Hath a Fall Part 1 v-If

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The Fat Bird Hath a Fall!! Part - 1 Preamble: Humans, howsoever

educated or enlightened are bound

to commit mistakes and errors. So

should we expect machines, whichare made by humans, to be

perfect? The question itself is in

perfect, and more critical for a

machine, when it works in the sky,

with complexity of sorts.

Incidentally an air plane is the

most complex machine build by

humans. It beats rockets and man-

made satellites by a fair margin.

Hence, wouldnt it be appropriate

to change the idiom, its not rocket

science to its not aero science.

The bus In AirAirbus is already on way to make sky traffic terribly congested, with all

the fat birds like Airbus A380s being put up there. Although an A380

possesses state of the art technology and is considered to be environmentally

friendly, even has far better fuel efficiency than any other air plane in the

skies, also its aerodynamics are such that it creates very low sound. But by

far the most important quality that it possesses is that it is the largest air

plane ever built by man. It can carry more than 600 passengers. But herein

lay the fear factor. Up till date, an accident which involved two boeing 747skilling 400 odd people, is considered to be the most fatal accident ever. Now

imagine an Airbus going down. It is universally accepted that although

probability of an air crash happening is very low at 11,000,000:1,

nonetheless the

Bus Train Air PlanePassenger carrying

capacity

80-100 600-1000 300-400

Accidents per year -- NA -- 3000 20

Deaths caused peryear

4000 1000 200

Cost 6-

7miles/gallon

1.5-2 miles/gallon 665

gallons/hourCrew Members 2 50-60 10-20

Probability of dying 1 in 250 1 in 115,000 1 in 10.46million


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probability of someone surviving in an event of an air crash is a

figure diametrically opposite, a dismal 1:10,000,0000. If its a goof

it is a big poof. It would kill people in excess of 600 in a few

seconds in an event of an A380 crash, which is more than the

number of people dying in terrorist attacks world wide each year.This is a scary thought. So, why not learn from the mistakes fast?

Hence the importance of this article where our objective is to learn

from our mistakes of the pasts, apply them in future aviation

projects and come up with a strategy with which we can achieve

zero defects in the design of an air plane. That is we are aiming

for the ideal. Ambitious, but certainly not impossible.

Objective: To achieve a perfect flight with Zero Defects

First off! Are We Safe In The Sky!


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A Back Flight To History. Back in the 1920s and 1930s, commercial air travel started its

journey. With it came safety concerns as the passengers were common

people rather than military. To enhance safety of the civilians traveling,

there would have to be a drastic improvement in the air plane design.

Technology was still in its nave stage. Crashes were common place.

Commercial planes were only used by American mailing services, which

crashed often. But increasing popularity of commercial air travel meantbetter safety standards. Design had to evolve. Hence a way to evolve must

be found. And this way was found precisely in 1931. On 23rd may 1931, a

plane carrying 8 passengers including one star football coach of America

died in a plane crash. Due to the celebrity status of the victims, there was a

thorough investigation done on the crash, a first of its kind. It was found that

the wing which was designed and manufactured using wood as building


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material was the culprit. After a thorough investigation it was found that on

that fateful rainy day, the wing of the plane being made of wood swelled up

on wetting and due to the additional pressure on the joints holding it in

place, the wing collapsed and the plane crashed. Thus it was decided after

the investigation that all planes made of wooden wings have to be

immediately grounded and burnt. And that all the wings of future planes

must be metallic. Due to a shortage of planes and high demand, there was a

great need to design a plane for commercial travel. Douglas, one

aeronautical scientist of America did just that. He designed one air plane

which is till date considered the best designed plane. And the technology has

evolved from that first to now. Once a perfect flying machine was designed

it was difficult to design a drastically different design. Learning from the

mistakes was one important way to improve design. Hence, NTSB (National

Transport Safety Board) was set up in the United States of America to

investigate in great detail any future air crashes.It is due to this effort on the part of the NTSB that air travel today is

considered to be the safest way to travel. And the probabilities shown in the

following figure demonstrate the same.

Close To Heaven Or Hell!!Following is briefly about some air crashes that occurred due to various

reasons:

The approach used to describe

the event is diagrammatically

displayed in the flow diagram.The basics of the accident analysis

are outlined. As our objective is to

achieve zero defects, a look into

the past will help us in not

committing the mistakes again in

the future. NTSB the leading body

in the world is involved almost in

most of the accidents. Local

investigative agencies help in theinvestigation. The terror that the

passengers of the air craft, which

has become a death ship for them

could be well imagined.


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Accident

Chronology of event

The Event in Brief

Investigation process

Learning Experience

Design changes

Aviation Safety

Lets study some actual mishaps and there root causes. In this

first part we will enlist two crashes and there case studies. In

the continued parts more case studies will be discussed.

American Airlines Flight 191 DC 10 The Event in brief

The plane takes off from Chicago airport on a clear spring day, as

the wheals leaves the runway it looses power on one of its engines

suddenly it roles to left seconds later the plane hits the ground and

disintegrates.

Investigation Process

In the investigation process it is found that on take off an engine fell

off due to structural faults. The DC 10 has 3 engines each weighing more

than 5 tons, one is on the tail and the other two hang from the wings eachconnected by the pile on. A pile on attaches to the wing at three points

two at the front one at the rear, it has dozens of components. The air

plane can fly normally even if it looses one of its engines. The flight data

recorders are recovered and they reveal some facts. The pilot was able to

stabilize the plane level just after it lost its engine. But, it started rolling

to the left. After close scrutiny of the pile on assembly that holds the

engines to the wings, investigators discover what they believe to be

probable cause for the engine falling off, a fractured bolt. A senior

metallurgist is called and he examines the bolt. The bolt reflected a

fatigued fracture. But the metallurgist from his experience reveals thatthe bolt was damaged during the flight not before. He saw no fatigue in

the bolt. The flange is another key piece of the pile on assembly. It is

recovered and close inspection reveals it is damaged, a damage which is

believed to be caused before the crash. The flange is on a bulk head

bolted to a clevis, when during maintenance the bolt is removed to detach

the pile on, for standard maintenance of the engines prior to the flight, the


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flange can move up on the clevis, cracking it and bending it exactly

matching the curve of the clevis. This is why the engine came off. But,

the air craft does not crash just by one engine coming off. Then a piece of

the left wing is found on the run way. The piece has been ripped away

from the rest of the wing by the engine which swung out up and over the

wing ripping it away. This crucial piece of the wing carries the hydraulic

unit crucial to moving the flaps up and down to steer the plane. Without

them the flaps would jam and the plane would be uncontrollable exactly

what happened on this flight and this is why the plane crashed.

Learning Experience

The most important learning experience was for the maintenance

people. Aviation safety depends on a large variety of people, from pilots

flying the air plane, to designers designing them, to maintenance men

maintaining them. Hence, every one of them must realize that they hold

the lives of a number o people in there hands and hence must beresponsible. Although there was irresponsibility and lack of realization of

the importance of the jobs on the part of the maintenance people that led

to this accident.

Design Changes

DC 10 air plane have a tarnished history. Although considered to be

one of the most sophisticated planes of its time. DC 10 planes have had

many accidents. This one although was not due to any major design flaw

but due to negligence in maintenance. Hence no design changes were

brought about after the crash although the aviation was made safer bychanges in the maintenance procedures.

Aviation Safety

As the after math of the accident there were stricter measures in

taking care of the air plane while in maintenance. This made the

aviation safer, by regulating the maintenance procedures.

Air Transat 236 a fully loaded AirBus A330 The Event in Brief

A fully loaded AirBus A330, with 306 people on board ran out offuel mid way over the Atlantic. How can a state of art computerized air

liner suffer such a catastrophic failure? It was a case of how pilots did

not trust there equipment and believed that a faulty sensor must be to

blame for the low fuel warnings that repeatedly alerted the pilots of a

possible fuel leak. In reality there was a major fuel leak in the number


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two engine of the plane. No one was killed in the accident and ultimately

the skills of the pilots helped land the plane safely.

Investigation Process

From the flight data recorders and voice recorders the investigators

found that the sensors repeatedly warned the pilots. But the pilots did notbelieve the sensors and opened the valve that shifts fuel from one engine

to another to prevent engine two from running out of fuel and flaming

out. This resulted in even faster fuel loss and ultimately fuel starvation to

both the engines and both the engines flamed out over the sea. Due to the

failing of both engines there was a loss of power on the plane and only a

limited number of functionalities of the plane were functional. So now a

sophisticated airbus 330 was nothing more than a glider although a

controllable glider. By the help of experience the pilots were able to steer

the plane to safety and land the plane on an island and save the lives of

all on board. Now the question remained that how did the leak happen.On close inspection of the plane it was revealed that there was a major

pipe that burst. It had a hole in it which was caused by friction. Another

smaller hydraulic pipe was very close to the larger fuel pipe and was

continuously rubbing with the larger fuel pipe. Due to this continuous

rubbing action the larger tube finally developed a fracture allowing the

fuel leak. Again it was not a case of faulty design but faulty repair by the

maintenance people. For maintenance one of the engines of the plane was

replaced recently and a replacement engine was placed for the time being

but the engine came without the hydraulic pump assembly, to overcomethis, the maintenance people fitted the pump assembly of an older engine

but they did not fit properly. The pipes were rubbing together for 5 days

and finally it gave way.

Learning Experience

Again this accident justifies the risk factor of 16 that we arrive at

from our data in a preceding section. Maintenance plays a major role in

air plane safety. This crash is another example of how maintenance lapse

almost caused 300 odd lives.

Design Changes

After the accident the airbus modified the checklist in case of a fuelimbalance, from now on computer checks all fuel levels on board against

the flight plan, which was earlier done by the first officer manually. And

it now gives a clear warning if more fuel is being lost than the engines

can consume. All in all this accident has made the flying safer.

Aviation Safety


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It is true what the NTSB investigators say, every crash makes

flying safer. Certainly this crash served its purpose.

Exploration Into The Future Safety.Quantitative Analysis

*reference for using the following analysis and table:Grades Points

A 1

B 2

C 3

D 4E 5

Rating Value

Ultimate Disaster 5

Crash 4

Probable Crash 3

Crash Landing 2

Land safely 1

Sr.

No.Causes of an

air crash

Probability

of crash due

to the cause

Rating

Grade for

probable

prevention

Risk factor

of the

cause

1. Human error 9/10 5 A 5

2. Cargo door 5/10 3 A 3

3. Hydraulic

Failure

5/10 3 D 12

4. Bird Strike 2/10 2 E 105. Both engine

fail mid

flight

4/10 4 C 12

6. Fuel Finished

(leak etc.)

4/10 4 B 8


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7. On-board

Computer

problem

2/10 1 B 2

8. Faulty

sensors

8/10 3 C 9

9. Maintenance

Insufficiency

7/10 4 B 16

10. Air plane too

old

3/10 2 A 10

How we arrived at the above results?Causes: Various air crash investigations undertaken by the NTSB (national

transport safety board) of the USA were taken as reference and it was foundthat the above mentioned ten causes represent the 80% range and was

sufficient to arrive at acceptable average results necessary for this article.

Probability of Crash Due to any of the causes: There were 100 investigations

taken *at random, from the various studied and a general probability was

arrived at. It is entirely the authors own versions and may not be taken as

official and final.

Rating: The probability is the basis of the ratings and takes into

considerations the number of people died in the crashes that had any of the

above mentioned causes. Again it is purely the authors awn version targeted

entirely to bring home a point and is only meant for this article and may not

be used for arriving at any other conclusions.

Grade for probable Disaster: The grade is given entirely on the basis of the

probability data.

Risk Factor of a Crash: The multiplication of the rating and grade is the risk

factor, the higher the number more is the risk of a crash.

Visual Aid to the above analysis.


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0

1

2

3

4

56

7

8

9

10

11

12

13

14

15

16

Rating Grade Risk Factor

Human error

Cargo door

Hydraulic Failure

Bird Strike

Both engine failmid flight

Fuel Finished (leaketc.)

On-boardComputer problem

Faulty sensors

MaintenanceInsufficiency

Air plane too old

Conclusion and InferenceAnalyzing the above table we infer that in the case of a maintenance

insufficiency the risk of disaster is the steepest, which in perfect harmony

with the various plane crashes investigated. There were a number of crashes

that took place due to the shear insufficiencies on the part of themaintenance. Interestingly the risk factor in the case of a human error is the

least. It is because the risk factor takes into account two factors. One is the

risk of an accident and another is the scope of prevention. And it is clear that

the risk of prevention of human error is most likely hence the risk factor is

lowest in that case. Although these are just some of the causes of most air

crashes, we can never predict how the next plane is going to crash. But there


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are some precautions that we might take. For example pray to God whenever

we board an air craft or for my non-spiritual friends I have some piece of

advice. Following statistics show two ways in which you can be saved in an

event of an air crash:

1. Mostly there are high risk months and low risk months. Following figure

demonstrate the same. Well, if you are not spiritual then you may see that

traveling in the month of April or May is the safest.

2. And in case you happen to board in one of the high risk months, do not

worry too much. We have another way to improve your probability of

living in case of an air crash. Just take the back seats.

Leonardo Da Vinci said, Learning never exhausts the mind. Hence we

must continue the Endeavour of a perfect flight. There is a law in

mathematics. The law of limits. Similar to what Heisenberg pointed out inhis theory of uncertainty that speed and distance cannot be measured

precisely together, the law of limit might point out that we can only go thus

far to a perfect flight. But we must keep getting closer and closer to the

ideal. We must not get fatigued from the thought that we will never achieve

the perfection. God made us humans and kept the perfection to himself. He

is the only perfect thing. Nonetheless, the closer the better.


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Jai Hind!

fat bird hath a fall part 1 v-if

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