15750363 human factors for aircraft maintenance

8/8/2019 15750363 Human Factors for Aircraft Maintenance

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Human Factors for Aircraft MaintenanceCompiled by Shahzad Khalil

Aug2007 1


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Contents of Course

1. General2. Human Performance and Limitations3. Social Psychology4. Factors affecting Performance5. Physical Environment6. Tasks7. Communication8. Human Error 9. Hazards in the Work Place

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Foreword

This course will benefit you both:

professionally at workplace&

personally in daily life

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Goal

Awareness of personal behaviour

Minimise errorsReduce the number of incidents Improve Safety of personnel & aircraft.

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Quotation: To err is human.

Quiz

Do human make mistakes?Are we human?Will we make mistakes?Would we like to reduce the possibility of mistakes?

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Introduction

Aviation: Safest forms of travelling.Chain of Events/humanerrors

Solution / Safety Net:If we break the chain at our level, the accidents will nothappen.

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The need to consider the human factor

Most important human factor:Ability to learn from experience & mistakescommitted by others.

Basic Rules:If it has gone wrong once, it will probably gowrong again .

Safety Net:At Design stage By manufacturer. ( e.g. Cross wires )At user level By following written procedures.

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Error in aircraft maintenance

Valujet Flight 597 :5 pax & 2 flight attendants injured.7 th Stage high compressor disk failed.

Investigated Causes:Fatigue crack.Poor Record-keeping.

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Reasons of Safety Improvement

better aircraft

better air traffic controlbetter weather forecasts.

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It is difficult to fix a faulty person than to fix a faulty component.

Do you agree?

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Human Error Estimates:

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Error Iceburg:A chain of minor events caused accidents.Heinrich Ratio:

Fatal Accidents 1Non Fatal 10Reportable accidents 30

Unsafe Acts (Not reported 600

Safety Net:Look below the surface for minor mistakes andnever leave anything unreported.

Saying :Take care of your hours and days,months and years will take care themselves.

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In aviation, Extremely Low Tolerance for Errors

Although we learn through mistakes, yetcannot afford to commit mistakes ourselvesand learn. We have to:

learn from the mistakes of others .

Proactive Approach :Taking measures, in advance, to avoid theoccurrence of any event.

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Causes & Casts of Air Accidents ex: Boeing

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A Simple Mistake by one Personaffects an Entire OrgansiationB767 was being brought into Hanger, collided with workstands.

Resulting Damage:The following equipment was damaged:Left-hand horizontal stabilizer Rudder Rear dock standsHangar wall

Cost factors: The following cost factors resulted from this one mistake:MaterialRegular and overtime labour Repairs to dock stands and hangar wallLoss of bay facility during additional repair Delayed or third party maintenance for other aircraftOperational complications due to aircraft unavailabilityInvestigation and corrective action

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Cost of one Night Stop at ForeignStation

Approximately 40,000/- USD

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Top seven causes of inflight shutdowns :Boeing analyzed the most common errors behind B767 inflight shutdowns; almost 70%were caused by installation problems.

Incomplete installation (33% ) Damage on installation (14.5%)Improper installation (11 %)Equipment not installed or missing (11%)Foreign object damage (6.5%)

Improper troubleshooting, inspection, test (6%)Equipment not activated or deactivated (4%)

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Top eight common maintenance errors

Incorrect installation of componentsFitting of wrong partsWrong electrical wiring of parts (including crossconnections)

Loose objects left in the aircraftNot enough lubricationCowling and/or access panels not securedFuel/oil caps and/or refuel panel not securedLanding gear ground lock pins not removed beforedeparture

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Who is right?

Both are right from their own positions.When you decideanything or assign anytask to someone, placeyourself on his positionand see the things ashe perceives.

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Aloha Airlines flight of B737had 18 feet (5.5m) of fuselage skin ripped off.

An AD called for close inspection of 1300 rivets.The inspector had 22 years of experience.The chief inspector had 33 years of experience.In the inspection prior to the incident no cracks were found .A post incident inspection revealed that there were at least 240 crackspresent at the last inspection prior to the incident .

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Comparison of Human Errors to Machine Errors

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Types of Errors

Active error - immediate effectHeight of aircraft not read correctly crash immediateeffect

Latent error - delayed effectBolt was corroded not seen so not replaced willultimately break.Delay between the mistake and consequence.e.g. Smoking.

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Conclusions from brief introduction of human Errors

Errors affect both lives and profit.Many errors are made, but it usually requires a chain of events for a serious incident to occur.

Although only a few errors will be the cause of anaccident, it is impossible to predict which one this will be.AMTs must be aware of the different kinds of mistakethey make and the possible consequences .AMTs must know the company's procedures for avoidingerrors and the benefit of following those procedures.

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9.2 HUMAN PERFORMANCE AND LIMITATIONS

Brain the CPU of Human body.Input devices of human body and their relatedsenses.

Five senses: : smell, taste, sight, hearing and touch .Minimum level of stimulation Thresholdvalues.

Health of our senses.Potections.

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Brain

Left half of brain thinksrationally . Used whiledealing with problems.Right half of brain thinksemotionally . Related tocreativity and clever ideas.Which one is correct to use?

Both should be used .

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Strategies

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Information Awareness

Five senses - the sources of information.Smell can warn us of dangers.Sense of temperature through touch .Extreme of touch is pain. sense of touch .Taste very rarely used.The two most used senses: Sight and

hearing .

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Detection & Awareness

Sight sense eyes .Minimum level of stimulation / thresholdlevel with naked eye :60 micron .Inspection involves:search and decisionmaking .

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Use of eyes:

Inspections: 80% of inspections are visual inspectionWritten documents: Different manuals.Job-cardsWriting what you have done.Written Communication:

LegibleAccurateComplete

Order of sentences.

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HearingUse ears .AF : 20 Hz 20 KHzVolume / Audio level in decibel(dB)Awareness threshold: 0 dB

Deteriorate with age and alsosuffers from non-reversiblepermanent damage when exposedto high level of noise.50% to 80% waking time spent inlistening .

Two ears and one tongue.

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Ear Protections

When sound volume > 90 dBEven at 85 dB if remain exposed for > 4 hours .

Earmuffs / Earplugs.Treatment of ears take years .

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What is the difference betweenHearing & Listening

Hearingis just the process of taking in sounds.not selective.Passive.Sound of fan, air-conditioner etc.

Listeninghearing with selective attention.Involves interpreting the sounds.Active.To each other.

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Listening

Interest in topic.Distraction toleranceAppropriate time & place.Listening instead of talking: two ears & one tongue .PreparationEye contactWhat is said and what is not said? Sometimes moreinformation in what is not said.Prejudices : decision already made.

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Hearing Damage

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Different Ways of Information Transfer:

Person to Person:Via verbal communicationVia written communication

Display / Product to person:

Job cardsManualsDisplaysIndicators

Person to Product:Key board of computer Controls in aircraft

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Attention and Awareness

Selective Attention:Monitoring several sources of information to decidewhether particular event has occurred e.g. deviantreading on several indicators in cockpit.

Focused Attention:Being task focused. Concentrating to one source.e.g. Mechanic reading in noisy environment.

Divided Attention

Sustained AttentionSecurity Guards viewing a TV monitor.

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Mental limits: Disassembly and Re-assembly

There is only one way to disassemble the nuts, but there are40, 000 wrong ways to re-assemble them.Knowledge and experience will help to prevent mistakes, butnobody can know everything (Human limitations)Use of Written instructions and Experience of colleagues cancompensate for these limitations.

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Claustrophobia and Physical Access

Claustrophobia:Definition: An irrational fear of being in aconfined or enclosed space.e.g. Maintenance in Fuel Tank.Use Life-Line

Space Availability:More space improves performance.

Controllability:Minimum restrictions due to clothes & shoes.

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9.3 Social Psychology

The area of psychology that deal with howgroups behave and how individuals are affected

by the group.

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Different Ways to Learn & %age Remembered:

Hear 25%

See 30-35%See & Hear 50%Say & Repeat 75%Do 90%

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Motivation

Willingness to put effort intoachieving a goal .

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Alfred Adlers Motivation Theory

All human behaviour is goal-directed .When given the chance to contribute, they becomeproductive, task-oriented employees and in result feelsignificant.

People are creative decision-makers .

An active role in solving problems and decision making.Humanity is socially embedded .Problems cannot be solved by one person in isolation.They are solved by co-operation and contribution.

Use is more important than possession .A person's knowledge and skills are of no value if they arenot used.

People (and organisations) function holistically .The whole is greater than the sum of the individual parts.A group effort be encouraged.

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Maslows Theory of Hierarchy of Needs

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Culture Issues

Corporate Culture:Develop a desirable corporate culture.Pleasant workplace and effective maintenance.

Philosophy:Mission Statement: Clearly worded and communicated.

Guidelines stating what is and is not acceptable.Ceremonies for appropriate recognition.Hearfelt concerns for employees.

Open communication.

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Teamwork

Planning, co-ordination and communication.

Team: a group of inter-dependent individualsworking together to complete a specific task.

Example: Football TeamIn maintenance, working as a team improvesproductivity and reduces injury and equipment

damage.

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Leadership

The ability to direct and co-ordinate theactivities of group members and stimulate / inspire them to work together to complete a

specific task .

Lead by example .

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Responsibilities of Leaders

Direct and co-ordinate team activityDelegate tasks to appropriate team membersMake sure team members know what is expected of them

Focus attention on important aspects of the situationAdapt to internal and external changes to theenvironmentKeep team members up to date on work-relatedinformation

Ask team members for work-relevant informationProvide feedback to team on performanceCreate and maintain a professional atmosphere

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Types of Leaders

Authoritative Leader:Runs the show alone. Sole decision maker.Controls all the resources.Dictates actions with little input from team members.

Participatory Leader:Encourages participation.Distributes resources and delegate power.Get maximum input from members

Group decisions.

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Which type of leadership is better?

Balance between the two types.

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When to use Authoritative and whenParticipatory?

Authoritative Participatory

Done quickly. Time available.

Task structured. Clear Answers.

Task unstructured. Inputsrequired.

Conflicts Work well together.

Accepts decision taken bysingle person.

Do not accepts decisiontaken by single person.

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9.4. Factors Affecting Performance

StressDefinition:

Physical or psychological tension caused by dealing

with difficult situations.Stressors

Personal problems.Work related problem.

Social problems.Cost of StressPoor work quality Public safety jeopardised.Heart diseases Sleeping problem

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Stress and performance

Stress in itself is notnecessarily bad.Positive level of stress:Best Performance.Negative level of stress:Poor performance.

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Time Pressures & Deadlines

Time pressure sets the pace of work.Stressful Situations:

Overload

Under-load

Fire Fighters:

Under-loaded & Overloaded

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Varying the Task

Alternate / swap tasks:Physical demanding with mentally demandingHigh awareness with low awareness

Long duration with short durationFrequent Breaks

Break can be a change of work.

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Components of Situation Awareness

Be aware of your surroundings.Use all the senses.

Fire , Fire, FirePerceiving : e.g. listening of some sound.Comprehending: What that sound mean?

Projecting: Thinking about possible consequences.

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Models

Are in diagram form.Drawn to understand complex systems.For example: model of braking system of bicycle tounderstand aircraft braking system.Block Diagrams, wiring diagrams etc.

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Why we draw models?

To identify the components of the system.To develop the strategies to improve thesystem.

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SHELL Model

S oftwareHardwareEnvironmentLiveware (Individual)Liveware (Group)

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9.7 Communication

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Definitions of Communication

Skill of passing information from on person toanother.Transfer of information from one place to

another.The dynamic and irreversible process bywhich we make contact and interpretmessages within a given situation or context.

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The Transactional Analysis Model

Is an attempt to explainhuman behavior,especiallycommunication.

Three minds or egostates.No good or bad egostate.A healthy personalityincludes all three.

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The Transactional Analysis Model (Contd.)

Parent :

OrdersClaims to know everythingCaring, encouraging,supportive & protective.

Sentences:Let me help you.Leave it to me, I will dothis.

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The Transactional Analysis Model (Contd.)

Adult :

Asks for reasons.Talk on equal level.Sentences :

What is your opinion?

I do not agree.

Child :

EmotionalFree & natural.Obey, retreat, be polite.Not sure of itself.

Sentences :I do not like you.I do not know, I wantleave.

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Dupont ModelEmotional Minds :

Responds faster.

Decisions made withoutanalysis.Sentences:

Hurry up.Forget it.

Rational Minds :Takes more time to react.Decisions made throughanalysis.

Balance

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R lt f g d i ti


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Results of good communication

Reach an understanding with one another.Co-ordinate their efforts.Agree who does what.Decide on actions and make decisionseffectively.Take correct action to reach their goals.

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Forms of communication Verbal communication

the spoken word.face-to-face or through an electronic medium such as atelephone, radio, loud speaker etc.

Non-verbal communicationas body language.Wave, smile or frown.

Written communication Manuals, Job-cards, letters, magazines, books, forms,e-mail etc.

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Communication model


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Communication model

Communication in its simplest form involves two people:The Sender : the speaker or writer who is transmittinga message.The Receiver : the person who sees, hears or reads

the message.FeedbackMessages filtered through feelings, opinions andintentions. The message includes body language.

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Three C s of Communication

Be c orrectStandard part names.

Be c omplete.Enough information.Be c lear

Say what you mean to say.

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The impact of information technology


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p gy

e-mail, voice mail, fax machines, mobile phones and pagers.Information technology (IT) improves communication inorganisations in the following ways:It cuts across time boundaries .It cuts across geographical boundaries.

It allows multiple, simultaneous reception. Bottlenecks can be avoided as electronic information channelsare typically direct between sender and receiver.It helps reduce paperwork.

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9.8 Human Errors

General Model of Human Error:

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Types of Errors

Example: John drives into water and the car begins tohydroplane.Slip - having a good plan , but bad execution: John's plan is topump his brakes, but he misses the brake pedal and steps onthe accelerator instead.Mistake - a bad plan is selected : John thinks that speeding upwill give him control over his car so he accelerates.Violation - the wrong procedure is performed intentionally :John learned from his driving teacher that he should pump hisbrakes in this situation, but his brother said that acceleration isbest, so John steps on the accelerator.

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Dirty Dozen

Aviation safety specialist, Gordon Dupont ,identified 12 most common human factor

maintenance errors , known as dirty dozenthat limit peoples ability to perform effectivelyand safely

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Dirty Dozen ( continued)Lack of communication

Lack of teamworkLack of assertiveness (not enough confidence).Complacency (too relaxed)DistractionPressureLack of resourcesLack of knowledgeLack of awarenessNormsStressFatigue

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1. Lack of Communication

Communication by:the spoken wordsthe written wordsgestures and facialexpressions

body language

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Sender-Receiver Model of Communication

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C t L g b k E t i


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Compare two Log-book Entries

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2. Lack of Team Work

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3 Lack of Assertiveness


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3. Lack of Assertiveness

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4 Complacency (T l d)


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4. Complacency (Too relaxed)

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5. Distraction

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7. Lack of Resources

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8. Lack of Knowledge

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9. Lack of Awareness

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11 Stress


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11. Stress

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12. Fatigue

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Shift Work


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Shift Work

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15750363 human factors for aircraft maintenance

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