EASA 145 & 66 Human factor Training

Maintenance

Human Factors Training

EASA 145 & 66

2

Maintenance Human Factors



This training is based on EASA 145, which

requires…

That maintenance organizations put in place a maintenance Human Factors program that

addresses ten (10) maintenance Human Factors issues, and where…

One (1) of the issues is the need to train maintenance staff to be competent in

maintenance Human Factors knowledge and skills

EASA 145 Maintenance Human Factors

Training Requirements

1. General / Introduction to human factors 2. Safety Culture

3. Human Error

4. Human Performance & Limitations 5. Environment

6. Procedures, Information, Tools and Practices 7. Communication

8. Teamwork

9. Professionalism and integrity 10. Organization’s HF Program

I. General

Introduction to

Human Factors

Definition

Human Factors is a technical discipline aimed at optimizing human performance within a system by

contributing to the planning, design, and evaluation of tasks, jobs, products, organizations, environments

and systems in order to make them compatible with the needs, abilities, and limitations of

6

Where Can Human Factors

Be Applied in Maintenance?

Manuals & Procedures

Training

Operational

Controls & Displays

Design for Maintainability Human/Computer Interaction Work Group Procedures

8

• Variations in Performance & limitations – Physical size & shape

– Physical needs (sustenance, sleep etc)

– Input/Output Characteristics – Information processing

– Environmental tolerances (temp, pressure, humidity, enclosed space, stress & boredom)

• Ergonomics

– Tool design & operation – Instrument interpretation – Work space & access – GSE reliability

10 Non-physical aspects of systems such as:

• Document design & layout e.g. maintenance manual

• Symbology and computer programmes • Procedures

• Training manuals

i.e. content and design • Rules and regulations

i.e. company and authority

• Extremes of temperature affects thought

processes

• Excess noise and vibration affects

concentration

• Shift work causes fatigue making error prone

12

• Leadership, co-operation,

teamwork, personality

interactions

• Staff/management relationships,

corporate culture & climate,

company operating pressures

• Domestic Pressure

14

Causes of Accidents

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1903 _TIME Today

~80% of accidents are now due to human error

~20% of accidents are now due to machine causes

Maintenance-Related Accidents

 Maintenance system failures, due to errors

and/or violations, can affect safety of flight in two different ways:

1. Primary Cause of an accident. Accident is due to the maintenance/inspection failure. Accident is not in any way due to flight crew action.

2. Contributing Factor to an accident. Accident

chain begins with a maintenance/inspection failure that is incorrectly handled by the flight crew, ultimately

16

Accident Where Maintenance Is

the Primary Cause

Kahului 737 Event

Post incident inspection revealed that there were at least 240 cracks present at the last inspection prior to incident.

Among the contributing factors to the error of not seeing the cracks…

Lack of resources–No proper platform or inspection lights.

Fatigue–Inspection carried out late at night.

Lack of technical knowledge–Not enough inspection training.

Complacency–Done other aircraft and had not find any cracks.

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Maintenance as a Primary Cause

Data provided in a recent Advance-Notice of

Proposed Amendment No xx/2007 from EASA*.

Primary Cause of HF-Related Accidents # of Accidents % of Total

Design 135 3%

Production 101 2

Operations (flight crew related) 3038 58

Maintenance 416 8

ATM 66 1

Dispatch 18 0

Loading 129 2

TOTAL HF-Related Accidents 3903 75 Non-HF-Related Accidents 1320 25

TOTAL 5223 100

*Data obtained from EASA Safety Analysis & Research. It is based on airliner accidents only, covering the period 1990 to January 2006. Only reports where causal factors have been positively identified are included in the analysis.

Accident Where Maintenance Is a

Contributing Factor

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Lima 757 Event

The aircraft's three static ports on the left side were obstructed by masking tape. The tape had been

applied before washing and polishing of the aircraft the day before the accident flight.

Work was begun on one shift and handed over to next morning’s shift.

Poor shift handover log was a contributing factor.

Mechanics and pilots both missed tape during walk around.

Safety Costs of

Maintenance Events 2003

The International Air Transport Association (IATA) Safety Report 2003 found that in 26% of the

accidents a maintenance-caused event started the accident chain.

IATA Safety Report 2006—40%

IATA Safety Report 2007—20%

IATA Safety Report 2008—15%

Note: IATA did not distinguish between maintenance as a Primary Cause vs. a Contributing Factor.

22

Monetary Costs of Maintenance Error

Maintenance error caused…

20% to 30% of in-flight shutdowns (IFSDs) at a cost of US $500,000 per IFSD

50% of flight delays due to engine problems at a cost of US $9,000 per hour.

50% of flight cancellations due to engine problems at a cost of US $66,000 per cancellation.

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Summary

About 80% of aircraft accidents today are caused by human errors.

Maintenance and inspection errors are the primary cause of 8% of the accidents.

Maintenance and inspection errors are a link in the accident chain in an additional 20% - 30% of the accidents.

Maintenance and inspection errors can also be very costly.

The whole industry (manufacturers, vendors, aviation

authorities, airlines, and maintenance providers) must work together to reduce the risk from these errors.

II. Safety Culture/

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Safety Culture



EASA 145 requires that a maintenance

organization develop a Safety Culture

within the organization.



One way to begin development of a

Safety Culture is to put the elements of

a Safety Management System into

Safety Culture

Safety Management System



Definition of culture/safety culture



Importance of a good safety culture



Elements of a good safety culture



Safety Management System (SMS)



International Civil Aviation Organization

(ICAO)



General characteristics and functions of

an SMS

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Definition of Culture



Culture = Customary beliefs, behavior

patterns, and traits of a racial, religious, or

social group



Any organization has a culture of its own

Management style

Morale

Acceptable behaviors

Definition of Safety Culture



What is a “safety culture” as it applies to an

aircraft maintenance organization?



A “safety culture” is a (maintenance

organization) culture in which safety plays a

major role.

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Importance of a Good Safety Culture



Safety, as it applies to maintenance, has

three components

1. Maintenance actions (e.g., an installation error) can lead to safety of flight issues

2. Mechanic actions can lead to personal safety issues (e.g., cuts, puncture wounds, and broken bones)

3. Maintenance actions can lead to environmental

degradation.



A good safety culture will reduce the

instances of all three of these events,

reducing the accident rate and, thus,

saving lives and money.

J. Reason—The Elements

of a Good Safety Culture

Informed Culture—A culture in which those who

manage and operate the system have current knowledge about the human, technical,

organizational and environmental factors that determine the safety of the system as a whole.

Reporting Culture—A culture in which people are

willing to report errors and near misses.

Learning Culture—A culture in which people have

the willingness and competence to draw the right conclusions from its safety information system, and the will to implement major reforms when the need is

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J. Reason—The Elements

of a Good Safety Culture

Just Culture—A just culture where an

atmosphere of trust is present and people are encouraged or even rewarded for providing

essential safety-related information, but where there is also a clear line between acceptable and unacceptable behavior.

Flexible Culture—A culture that has

organizational flexibility typically characterized as shifting from the conventional hierarchical structure to a flatter professional structure.

Achieving a Safety Culture



A Safety Culture is achieved over time,

requiring:

A commitment to safety from the Senior

Management down through every worker in the organization.

A process for achieving safety. This process often is called a Safety Management System.

III. Human

Performance

& Limitations

Human Performance &

Limitations

Normal curve

Human strengths and weaknesses Vision Hearing Information processing Attention and perception Memory Speed/accuracy trade-Physical work

Fatigue and sleep

Claustrophobia and physical access

Fitness and health

Alcohol, medication, and drugs

Repetitive tasks/ complacency

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Introduction to Human Performance

Human beings have strengths and weaknesses

Tasks that do not account for human limitations result in:

 Errors

 Injuries

If you review a task or work station, do not ask:

Can it be done? Ask:

Can it be done safely and correctly by the people who do the job? Vision Hearing Cognition Strength Reach

Humans Are Better

than Machines in…

 Detecting small amount of visual and acoustic energy.

 Perceiving patterns of light or sound.

 Improvising and using flexible procedures.

 Reacting to unusual or unexpected events.

 Storing very large amounts of information for long periods and recalling relevant facts at the appropriate time.

 Applying originality at solving problems.

 Reasoning inductively.

 Exercising judgment.

 Learning from experience.

“Use a human operator when a system component is needed that can think on its feet, process information

in ways that could not be predicted, and can then act effectively using the result.”

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Machines Are Better

than Humans in…

Responding quickly to control signals.

Applying great force smoothly and precisely.

Performing repetitive, routine tasks.

Storing information briefly and then erasing it completely.

Reasoning deductively, including computational ability.

Handling highly complex operations—doing many different things at once.

Other Major Differences

Machines can be modified, redesigned, and retrofit—humans cannot.

Humans are born with innate, genetically determined differences that are shaped by the environment.

Innate aptitudes or abilities are developed through education and training.

Machines can be manufactured to be identical— with (nearly) identical output or performance.

Humans are not identical and vary across all sensory, cognitive, physical, and performance characteristics.

Specific aspects of human performance can be made more equal through education and training.

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Vision Performance Issues

Being able to see clearly is vital

in aircraft maintenance and

inspection.

•Vision requirements are task

based.

•Illumination requirements are

task based.

•Technicians must recognize

their individual visual

The Normal Visual Field

Provide visual access to work area...

 Without excessive bending

 For both short and tall people

Visual access is critical to...

 Doing the task

 Visual validation of the task

Examples of problems due to poor visual access:

 Incorrect attachment

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Colorblindness

 Complete color blindness is quite rare.

 Most people are actually color deficient and have problems seeing red and green.

 About 10%-15% of males and 1% of females are color deficient.

 Most do not even know.

 They learn to compensate with degrees of brightness and

texture.

 If you find you have it, avoid errors by asking other people

when you are unsure. An estimation of what the spectrum looks_{like for different types of colorblindness.}

No Red receptors

No Green receptors

A Quick Colorblindness Test

This is a demonstration.

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What Numbers Do You See?

Recommended Illumination Levels*

Tasks

Illumination Levels in Lux _Light

Source

Recommend Minimum Perceiving small details with low contrast for

prolonged times, or where speed and accuracy are essential, such as repairing small components, inspecting dark materials

1650 1075 General service plus supplementary Perceiving small details with fair contrast where speed

and accuracy are not so essential, such as electronic assembly

1075 540 General service and/or supplementary Prolonged reading, desk or bench work, general office

and laboratory work, such as assembly work and filing records

755 540 General service and/or supplementary Occasional reading, recreation, reading signs where

visual tasks are not prolonged, such as reading a bulletin board

540 325 General service and/or supplementary Perceiving large objects with good contrast, such as

locating objects in a bulk supply warehouse

215 110 General service Passing through walkways and handling large objects, 215 110 General service

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The Human Auditory System

 The outer ear collects sound

 The middle ear channels sound to the ear drum

 The inner ear converts sound to nerve impulses

 Tiny hair cells (cilia) in the Cochlea vibrate with different sounds

 Excessively loud noise can result in the hair cells stretching too far and breaking

 Listening to the same frequency or pitch for a long time can also damage the hair cells

 Listening to loud noise for a long period can also cause fatigue

Outer Ear Middle Ear Inner Ear Ear Drum

Protect Your Hearing!!



Types of Hearing Protection

Disposable plugs

Reusable plugs

Custom-fitted plugs

Ear muffs



Wearing Hearing Protection Properly

Follow package directions when putting protection on.

Make sure the selected protection fits properly.

Maintain hearing protective devices in a sanitary condition.

Make sure nothing interferes with the use of hearing protectors (e.g., eyeglass frames).

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Sound Intensity Levels

Db Level Example Dangerous Time Exposure

0 Lowest sound audible to ear None 30 Quiet library, soft whisper None 40 Quiet office, living room None 50 Light traffic at a distance, refrigerator None 60 Air conditioner at 6 m., conversation None

70 Busy traffic, noisy restaurant Critical level begins 80 Subway, heavy city traffic, alarm clock More than 8 hours 90 Truck traffic, lawn mower, shop tools Less than 8 hours 100 Chain saw, boiler shop, pneumatic drill Less than 2 hours 120 Rock concert in front of speakers, Immediate danger

sandblasting, thunderclap

140 Gunshot blast, jet plane @ 15 m. Any exposure is bad 180 Rocket launching pad Hearing loss inevitable

Information

Processing/

Attention and

Perception/

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A Model of

Human Information Processing.

(Adapted from Wickens, C.D. Engineering Psychology and Human Performance. Columbus, Ohio: Charles E. Merrill Publishing Co., 1984.)

 Three types of memory

 Sensory memory

 Working or short-term memory

 Long-term memory

 Attention (concentration) is a limited

resource, which must be shared between

 Observing the situation

 Deciding on a response

Attention and Selection

The first process of memory is attention.

There is much more information in your environment than you can process at any one time.

You must make choices (conscious & unconscious) regarding the stimuli to which you will attend.

Early theory was that we could only attend to one thing at a time.

That theory is still believed to be true. However, we can switch our attention quickly, especially if the

information comes from different “channels” (e.g., hearing and vision).

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Working (Short-Term) Memory

This is the memory that we use, for example, when some one gives us a phone number to call or gives us directions on how to find an office in a building

Working memory lasts only about 20 seconds,

although you can make the memory last longer by “repeating” the information to yourself “in your head”

Working memory can hold about 7 + 2 (5 to 9) “chunks” of information. For example, you will remember the name “

Steven” as one “chunk” of information, not as six separate letters.

Moving Information from Short-Term

Memory into Long-Term Memory

All verbal information goes first into the short-term memory.

When it is rehearsed (recited), part of it goes into long-term memory.

The rest of it, usually the part we are least

interested in, returns to short-term memory and is then forgotten.

Whether new information is "stored" or "dumped" depends, then, on our reciting it out loud and on our interest in the information.

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Accessing Long-Term Memory

Two ways to access your memory:

Recall—coming up with the information from memory

 Fill-in-the-blank exams

 Coming up with a person’s name.

Recognition—recognizing the correct information

 Multiple choice tests

 True/false tests

 Recognizing someone that you know.

Recognition is easier than Recall.

Often need to recall information we learned long ago. How quickly/reliably we recall it depends on:

Activation: How long since we last used the information.

Why Do We Forget?

 Three possibilities

1. The memory fades away (decays) over time

2. Interference (overlaying new information over the old)

3. Lack of retrieval cues.

 Data now suggest that we forget because of 2 and 3 above.

 In other words, once we have stored something in long-term memory, it is always there…we just have trouble retrieving the information.

56

Negative Transfer of Training

When you learn new material, old material that you learned before is still in long-term memory.

If the new material is similar to the old material but with some small differences, you can become

confused.

 Example: Mechanic knows how to replace a hydraulic pump on airplane A. The airline buys a newer model--airplane B.

 The pump bolts on airplane A must be torqued to 50 ft lbs

 The pump bolts on airplane B must be torqued to 60 ft lbs Later, the mechanic makes an error by:

 Replacing a pump on airplane A and tightening the bolts to 60 ft lbs, or

 Replacing a pump on airplane B and tightening the bolts to 50 ft lbs.

MESSAGE: Be sure to check details when things

58

Bio-Mechanics

Human Force Application Spine Geometry Work Posture

Occupational Risk Factors for

Cumulative Trauma Disorders

Force

Vibration

60

Neutral Position of

OK

Avoid

62

OK

Avoid

OK

Avoid

64

Neck Flexion

Back Flexion

66

Squatting

Kneeling

68

Hands Above Head or

Elbows Above Shoulders

Repetitively Raise Hands Above

Head or Elbows Above Shoulders

70

Highly Repetitive Motion –

Neck, Shoulders, Elbows, Hands

Highly Repetitive Motion and

Forceful Exertions with Hands

30o

72

Pinch Grip

Objects weighing > 1 kg per hand

or force > 2 kg per hand

Pinch Grip Plus Repetitive Motion

74

Pinch Grip Plus Wrist Deviation

30o

Power Grip

76

Power Grip Plus Repetitive Motion

Power Grip Plus Wrist Deviation

78

Repeated Impact - Hands

Repeated Impact - Knees

80

Intensive Keying and Mousing

Lifting

82

Pushing/Pulling

84

Workstation Design

 Design work stations for a range of people, not for the average person

 Permit several different working positions

 Design should start from the point where the hands spend most of their time

 Work should be conducted

between shoulder and waist height

 Raise the work surface for work that requires precision, so it is closer to your eyes

 Lower the work surface for work that requires more force so your arms are in a more neutral position

 Boeing airplanes are designed for people from 157 cm to 193 cm

 A drill which allows the user to change grip positions

 A component work bench which holds the component in the center and the tools around it

 Getting a ladder so that you are not working over your head

 Raising a manual to see detail

or a component work bench which moves up and down.

 A component work bench which holds a hydraulic pump at about waist high

Fatigue

and

86

Fatigue



EASA-145 requires the organisation’s

planning procedures to take into

account the limitations of human

performance, focusing on fatigue.

Definitions



Fatigue—A feeling of lack of energy,

weariness or tiredness. Also called

tiredness, weariness, exhaustion, or

lethargy. Fatigue is a normal response to

physical exertion, emotional stress, and

lack of sleep.



Alertness—Vigilantly attentive and

watchful; mentally responsive and

perceptive.

88

Effects of Fatigue



More than 100,000 car accidents annually in

the US are fatigue-related



Disasters such as:

Chernobyl (Russian nuclear power plant)

Three Mile Island (US nuclear power plant)

Bhopal (chemical release in India)

Exxon Valdez (oil supertanker accident in Alaska)

were officially attributed to errors in

judgment induced by fatigue.

Effects of Fatigue

Overall performance gets worse Loss of motivation Slowed reactions Forgetful Poor cognitive functioning Thinking Reasoning/judgment Problem solving/ Loss of creativity

Withdrawal from social situations

Mood changes

Increase alcohol use

Long term health can degrade

90

Our Circadian Sleep Wake Clock

A le rtn es s Low High 6 am Noon 6 pm Midnight 6 am Time of Day 3-5 am and pm = sleepy 9-11 am and pm = alert

Sleep



Sleep is defined as a state of partial or full

unconsciousness during which voluntary

functions are suspended and the body rests

and restores itself.

Lying down

Little movement

Do not respond as readily to disturbances

Reversible—can wake up

92

Sleep

Still not totally sure why we need sleep, but there are two theories…

Energy conservation—sleep to conserve energy (old theory)

Restoration (new theory)

 Neural circuits in the brain are “rewired”

 Memory is consolidated and strengthened

 Short-term memory items move into long-term memory

 Growth hormone levels are restored

 Blood pressure drops

 The cells in your organs are strengthened by protein synthesis

 Sleep breaks your stress pattern.

Also, we know that bad things happen if we do not sleep.

Effects of Missing Sleep

A person who loses one night’s sleep will generally be irritable and clumsy during the next day and will either become tired easily or speed up because of adrenalin.

After missing two night’s sleep, a person will have problems concentrating and will begin to make

mistakes on normal tasks.

Three missed nights and a person will start to visually hallucinate and lose grasp of reality.

94

How Much Sleep Do You Need?

Depends on…

Age

Health

Circadian rhythm

Body metabolism

Physical exercise level

The quality of the sleep

Amount of recent sleep

Body temperature Personal differences. “Magic number” of 8 hours of sleep is an average. Short sleepers—Need around 6 hrs of sleep. Long sleepers—Need around 9 hrs of sleep. 1 in 25 people need more than 10 or less than 5 hrs of sleep.

Avoiding Fatigue—No Shift Rotation

Getting a Good Night’s Sleep

Get up and go to bed at the same time.

If you are tired, go to bed early.

Use your bed only to sleep—no reading, eating, etc.

Keep the bedroom dark, quiet, and cool (58ºF/15ºC).

Exercise in the morning or early afternoon, not evening.

Do not eat a heavy meal before bed--a light snack at most.

No alcohol before bedtime, no caffeine after early afternoon, and avoid nicotine.

Quit worrying about falling asleep—it keeps you from falling asleep!

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Avoiding Errors While Fatigued

Admit you are tired!

Remain physical to remain alert.

Exercise/stretch at frequent intervals.

Talk to people.

Drink plenty of liquids.

Take a nap.

Avoid tedious, boring work.

Work with somebody else so you can catch each other’s errors.

Drugs and Diet

 Using drugs to get to sleep should be a last resort, because these drugs decrease REM and deep sleep.

 But, remember, there are “drugs” in food, also (like caffeine in coffee, tea, soft drinks, and chocolate).

 Thus, it makes sense to approach food and drugs together.

 Food and drugs release chemical that interact with our basic body rhythms. This interaction is one cause of the varied effects they produce.

 One step in controlling the bad effects of foods and certain drugs is to control when we consume them.

 If you are a “morning person,” the use of “uppers” like coffee and sugar-coated cereal in the morning makes no sense.

 Another control strategy is to avoid the combined consumption of food and drugs that have similar effects.

 For example, combining “downers,” such as alcohol, sleeping pills, and pain medication can be particularly dangerous.

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Drugs and Diet

Food in the stomach causes the stomach walls to stretch. The more the stretch, the stronger the signal to the body to send blood to the stomach to aid digestion.

Diverting too much blood to the stomach by overeating can create a shortage of blood elsewhere, like your brain, which causes you to feel sluggish following a big meal.

Eating frequent, smaller meals is preferable to eating a few large meals before and during work.

Eating smaller meals in the hours prior to heavy physical work is a key dietary strategy for shift workers.

Physical Fitness

The Drug and Diet control strategies that we have discussed are meant to decrease the build up of stress resulting from shift work.

However, some stress will still occur.

One factor that clearly improves our ability to cope with stress is physical fitness.

Shift work tends to drain your energy levels; fitness tends to build up your energy levels.

Physical activity can burn off excess energy and start the cycle

leading to a relaxed state that leads to good deep (non-REM) sleep.

Regular physical activity can help stabilize body rhythms and is

helpful in speeding the resettling of body rhythms in the first few days of a shift change.

100

“Putting It All Together” to Get a

Good Sleep after Your Night Shift

Determine how much sleep you need and try to get it every day. Use naps, as necessary.

Mental relaxation before bed

Physical relaxation before bed

Control your drugs and diet

Get physically fit

Deal with any sleep-related medical problems

Keep the bedroom dark, quiet, and cool (15ºC)

Use sun-blocking shades

Work with family and neighbors for bedroom quiet

Wear sunglasses on the drive home to “fool” your brain

Take a nap before the night shift starts in addition to your after-shift sleep.

Repetitive Tasks

Complacency

102

Complacency



Complacency

= Self-satisfaction

accompanied by unawareness of actual dangers or deficiencies.

Mechanics can become complacent when they have done a task over and over again without making an error.

Inspectors can become complacent when they have done an inspection many times before

without finding a problem.

Complacency

104

Environment



Stress and anxiety

Definition Why worry? Symptoms Stressors Physical Psychological



Conditions of the

work environment

Cold Heat Illumination Noise level

What Are Stress and Anxiety?

 Stress is a physiological reaction to physical and psychological factors (stressors) in our environment.

 Anxiety (also called angst or worry)…

 Is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components.

 It is the displeasing feeling of fear and concern in either presence or absence of psychological stress.

 Anxiety can create feelings of fear, worry, uneasiness, and dread.

 Anxiety is also considered to be a normal reaction to a stressor.

 In other words, stress and anxiety are about the same thing.

Stress/anxiety

Stressors Adaptations

106

Stress/Anxiety and Performance

Physical & Psychological Stressors

Physical stressors Illness  Acute  Chronic Environment  Temperature  Vibration  Noise  Fumes Fatigue  Shift work

 High work load.

Psychological stressors Unpredictability Uncertainty Uncontrollability Bereavement/tragedy Daily annoyances  Time pressure  Peer pressure  Management pressure Chronic stressors  Home environment

108

Why Worry About Threat

Stress/Anxiety?

Human Error Injury Illness Reduced Productivity

Conditions of the

Work Environment

110

Another Effect of Heat and Cold

on Work Performance

Some airlines have noted an increase in

maintenance errors in line maintenance during the summer. Why?

It is so hot outside or on the aircraft that the mechanic works quickly so that he can get back to the

air-conditioned building.

 Speed/accuracy trade-off applies, so errors increase.

Similar thing happens during winter

Work quickly to get in out of cold.

Have to wear heavy gloves and clothing, so that it is harder to do the work. Thus, errors increase.

V. Procedures,

Information, Tools, and

Practices

112

Procedures, Information,

Tools, and Practices



Visual inspection



Task inspections/duplicate inspections



Planning



Work logging and recording



Procedure—practice mismatch



Technical documentation—access

and quality.

Visual Inspection Outline

Definitions

Visual inspection—search and decision

Factors affecting visual inspection

Task Factors

Subject Factors

Equipment Factors

Environment Factors

Social Factors

Concept of Damage Tolerance

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Visual Inspection

Over 80% of inspections on aircraft are visual inspections.

Visual inspection is often the most economical and fastest way to find defects on an aircraft.

Airframe manufacturers and airlines depend on regular visual inspections to ensure the continued airworthiness of their aircraft.

Definition of Visual Inspection

Visual Inspection means inspection using either or all of human senses such as vision, hearing, touch and smell.

Visual Inspection typically means inspection using raw human senses and/or any non-specialized

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Types of Inspection

General visual inspection (GVI)

Detailed inspection (DET)

Definition of General Visual

Inspection (GVI)

 A visual examination of an interior or exterior area, installation or assembly to detect obvious damage, failure or irregularity. This level of inspection is

made from within touching distance unless

otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is

made under normally available lighting conditions such as daylight, hangar lighting, flashlight or

drop-light and may require removal or opening of access panels or doors. Stands, ladders or

platforms may be required to gain proximity to the area being checked.

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Definition of a Detailed Inspection

(DET)

An intensive visual examination of a specific

structural area, system, installation or assembly to detect damage, failure or irregularity. Available

lighting is normally supplemented with a direct source of good lighting at an intensity deemed

appropriate by the inspector. Inspection aids, such as mirrors, magnifying lenses, etc. may be used. Surface cleaning and elaborate access procedures may be required.

Some of the “Operating Rules”

Normal cleanup procedures are to be used prior to

conducting general visual or detailed inspections. Specified cleanup procedures are to be used for special detailed

inspections, if necessary. Sealant and corrosion protection finishes should only be removed when specified and

restored in accordance with the Corrosion Prevention Manual after the task is completed.

Excessive dust, debris, or overspray of corrosion inhibiting compounds found during any inspection are considered to be an unsatisfactory condition possibly reducing the fire resistance of the airplane design. Cleanup of these

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Definition of a Special

Detailed Inspection (SDI)

An intensive examination of a specific item(s),

installation or assembly to detect damage, failure or irregularity. The examination is likely to make

extensive use of specialized inspection techniques and/or equipment.

Special detailed inspections are to be used when

specified for inspecting hidden details or may be used as alternatives to detailed inspections.

NDT

Typical Aircraft Defects Found by

Visual Inspection

Typical airframe defects that can be found by visual inspection include…

Cracks

Corrosion

Disbonding

Other defects that can be found by visual inspection include…

System and component wear

Accidental damage

Environmental damage from long-term storage, sunlight, etc.

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Factors Influencing

Visual Inspection



Task Factors



Subject Factors



Equipment Factors



Environment Factors



Social Factors

Task Factors



Size/complexity of the object searched—

in general, search time is linearly related to either

search field area or number of inspectable items in the field.



Number of different types of defects

—the

greater the number of types of defects, the slower the search performance and/or the lower the “hit” rate.



Defect/background contrast—

higher

defect/background contrast produces faster and more accurate searches.

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Task Factors contd.



Defect size—

larger defects are generally found more accurately and faster than smaller defects.



Probability that the item contains a defect

—

the a priori probability that there will be a defect is positively related to hit rate and false alarm rate.



Timing/pacing

—in general, a self-paced

inspection task is more effective than an externally-paced task.

Task Factor—Company

Inspection Instructions

Before certifying any work, you must be satisfied that all

components, parts and materials utilized have been obtained from approved sources, are of the correct specification, and are completely serviceable. You must also ensure that all work are performed in accordance with current and approved Maintenance Schedules, Maintenance Manuals, Overhauls Manuals, Repair Test Schedules/Capabilities List, Drawings or any other relevant technical publications, and that all applicable Mandatory

Modifications, Inspections or any other special requirements have been duly carried out. In the case of repairs not covered by the approved technical publication, all work performed must be in accordance with the approved instructions of the equipment owner, e.g., Engineering Notes issued by the Engineering Department.

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Subject Factors

Inspector demographics—age, experience, and gender (no affect)

Training—not the same as experience. Even experienced inspectors can improve their performance (often dramatically) with a well-designed training program, which is based on a task analysis and which provides Knowledge of Results to the trainees.

Visual performance—not related to visual acuity as measured by a Snellen Chart. The size of the visual lobe is a predictor of inspector performance.

 However, studies done by the US FAA found that 20/20 vision or correctable to 20/20 should be required

for inspectors.

Cognitive performance—people with the ability to dis-embed objects from a complex/confusing background make better inspectors.

Hidden Figure Example

Inattentional Blindness and

Human Errors/Accidents

Someone performing a task simply fails to see what should have been plainly visible and cannot explain the lapse

afterwards.

Inattentional blindness causes accidents when attention mistakenly filters away important information, due to a

combination of factors: low conspicuity, divided attention, high expectation, low arousal.

People are unaware of the blindness. Training mainly affect conscious, voluntary behavior.

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Equipment Factors



Magnification

—increasing magnification may only change the speed-accuracy trade-off with higher

magnification improving target detection at the expense of speed.



Field integration

—using a “known perfect item” for comparison during the inspection.



Visual enhancement

—specific to NDI.



Human/machine function allocation

—specific to NDI. Typically shows that a hybrid of human and machine functions work better than either alone.

Environment Factors

Visual environment—correct lighting is important both for physical inspection and to avoid glare in computer-based inspection.

Auditory environment—no necessarily clear affects, although some studies show that noise >90 Db worsened inspection performance.

Thermal environment—some data to suggest that really hot and really cold environments have a negative affect on inspection.

Workplace comfort—no data. However, the myth that comfortable inspectors lose vigilance has been refuted.

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Social Factors

Working period—detection performance decreases rapidly over the first 20-30 minutes of a vigilance task (e.g., watching radar), although this phenomenon is hard to replicate in typical visual inspection tasks.

Job design—rest periods have been shown to improve performance.

Supervision, instruction and other pressures—from

signal detection theory, we know that criterion used by an inspector for reporting defects is influenced by the sum of all biases on the inspector. These biases are affected by a priori probability of a

defect and also by the perceived costs of misses and false alarms, which can be affected by supervisory instructions/reprimands.

Information environment—both feedback of inspection

performance (knowledge of results) and feed forward information (where to look for a defect) have been shown to improve inspection performance.

Summary

Over 80% of inspections on aircraft are visual

inspections, which are often the most economical and fastest way to find defects on an aircraft.

Visual Inspection means inspection using either or all of human senses such as vision, hearing, touch and smell.

A visual inspection includes a search and a

decision. The decision criteria can be influenced by outside factors, such as management pressure.

Common aircraft visual inspections include system inspections, structural inspections, and zonal

Error Capturing/

Task Inspections

and Duplicate

Inspections

Error Capturing



Error capturing = Adding a task to find a

mistake.



Common error capturing tasks

Operational/functional checks

Mechanic/pilot pre-flight walk around checks

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Task Inspection

Task (Job) cards typically have two types of signoff:

Worked by (Discussed later under “Norms.”)

Checked by

What does SIAEC’s GMM say the “checked by” person is supposed to do in order to feel

comfortable in signing off the task or sub-task?

Supposed to watch the whole task, or the critical parts of the task, being performed?

Must have a “high degree of confidence that the work has been carried out correctly.”

What Standard Do You Inspect To?

Many are found in the Aircraft Maintenance Manual (AMM)…

Chapter 20 Airframe Standard Practices

Chapter 51 Standard Practices and Structures

Planning of Tasks,

Equipment, and

Planning of Tasks,

Equipment, and Spares



Planning of Tasks, Equipment and Spares

•EASA 145 does not require a procedure

on the planning of work.

•EASA 145 and AMC material clarifies the

objective of good planning and includes

the elements to consider when

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Planning of Tasks, Equipment,

and Spares

Planning is critical to ensure that there are adequate…

Appropriately qualified and alert maintenance staff

Tools

Equipment

Material

Maintenance data

Facilities

for scheduled and un-scheduled maintenance.

Long-term planning.

Planning of Tasks,

Equipment & Spares

Planning consideration should be given to…

Logistics.

Inventory control.

Space availability (hangar and floor space).

Man-hours estimation.

Man-hours availability.

Preparation of work.

Co-ordination with internal and external suppliers.

Scheduling of safety-critical tasks during periods when staff are likely to be most alert, and avoiding periods when

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Work Logging and Recording

Importance of proper work logging/recording



All work on an aircraft should be documented.



Work sign-offs should occur soon after the

sub-task is completed. Do not wait until the end of

the task to sign off all “worked by” blocks.



Any work done on the aircraft that is not

covered in the maintenance manual (e.g.,

loosening a clamp on a wire bundle in order to

get access to a part) should be recorded,

Technical Documentation



EASA 145 addresses technical

documentation (poor maintenance data)



Inaccurate, ambiguous, incomplete

maintenance procedures, practices,

information or maintenance instructions

contained in the maintenance data used by

personnel must be reported to the author of

the data.

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Technical Documentation



The US Federal Aviation Administration

recently did a study of aircraft maintenance

manuals (AMMs). They found that:

The manuals rarely had technical errors in them, but…

The manuals were “not written by mechanics,”

meaning that the order of the tasks typically does not follow the way in which a mechanic would

Documentation and

Maintenance Errors

MEDA investigations have found that

documentation is the most frequent contributing factor to maintenance error.

Problems include

Not used (50% in MEDA investigations)

Not understandable

Incorrect step

Conflicting information

No illustration.

Team Behavior

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Overview



What Affects

Team Behavior?



Responsibility



Motivation



Norms



Culture



Effective Team

Behaviors



Communication



Assertiveness



Situation

Awareness



Leadership

Responsibility



Responsibility is...

Recognizing that you can affect the team’s success.

Choosing to act to help that success.



In a team, we tend to feel less

responsible.

“Someone else will do it.”

“The whole team agreed.”

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Social Influence



How behavior is influenced by the

social environment and the presence of

other people



Obedience to authority

Examples of Taking

Responsibility



Admitting and fixing errors.



Saying something about a situation when

you know there is something wrong.



Addressing non-critical problems

 Picking up debris from the ramp

 Finding the safety wire you dropped.



Maintaining professional responsibility.

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Professionalism—Some Examples of

“Unprofessional” Behaviors in Maintenance

Memorizing tasks instead of using manuals/cards.

Not using torque wrenches or other calibrated tooling.

Troubleshooting through experience, instead of using the Fault Isolation Manual (FIM).

Deviating from maintenance manual procedures.

Failing to attach “Do Not Use” tags when pulling circuit breakers and switches.

Skipping operational or functional tests.

Signing off for tasks neither seen nor checked.

Providing minimum information in task handover log.

Failing to document work not specified in the manual (e.g., loosening a clamp on a wire bundle).

Why Do We See

“Unprofessional” Behavior?

Behavior starts to “stray” from the professional

standard for various reasons (uncomfortable, time constraints, calibrated equipment unavailable).

Supervisor does not intervene.

Staff believe that supervisor does not care.

Behavior is seen as low risk.

Unprofessional behavior becomes the norm.

Existing workers put peer pressure on new hires to conform to these behaviors.

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Why Do We See

“Unprofessional” Behavior?

Supervisor actually rewards unprofessional behavior.

“We’ve got 4 days of work to do in 2 days. I don’t care what you do, just get it done. I am going into my office and closing the door. [After meeting the 2-day deadline.] Way to go guys!! Pizza for everybody.”

Supervisor threatens punishment for carrying out professional behavior.

“What do you mean you don’t feel qualified to do the job? You’re trained. You’re certified. Go out there and do that work. You want to keep your job, don’t you?”

Then How Do We Move Back to

Professional Behaviors?



What not to do…

Pick out an offender and punish him/her in front of their work group.

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Then How Do We Move Back to

Professional Behaviors?

What you should do…

Management decides what behaviors are desired.

Management and labor meet to agree on the new behaviors. Address issues brought up by labor, e.g.,

 Time it will take

 Availability of equipment, calibrated tools, parts, etc.

Supervisors are provided training on new expectations

 No threats to staff if they are doing correct behavior.

 Reward correct behavior and model correct behavior.

Labor told of progressive punishment for failure to exhibit new behaviors

 Verbal warning

 Letter to file

Motivation



Motivation = A process within a person that

causes the person to move toward a goal

that is rewarding.



Two types of motivation:

Intrinsic—We move toward a goal because of

rewards that are internal to ourselves (e.g., feelings of satisfaction or accomplishment).

Extrinsic—We move toward a goal because of

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Motivation Affected by Beliefs



Motivation is determined both by…

The intrinsic or extrinsic reward, and

The belief that effort will result in achieving the reward.

Example: Someone who does not believe they can win a race will not be motivated to try hard

to prepare for and win the race, no matter how badly they want the $100K prize money.

Performance = Skill X Motivation

Performance is determined by BOTH:



Skill

&



Motivation

Example: Someone with medium skills

and high motivation can out perform

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Implications for Management

Management must not only provide hygiene factors to avoid employee dissatisfaction, but must provide motivation factors intrinsic to the work itself in order for employees to be satisfied with their jobs.

The job should have sufficient challenge to use the full abilities/skills of the employee.

Employees who demonstrate increasing levels of ability/ skill should be given increasing levels of responsibility.

If a job cannot be designed to use an employee’s full abilities/skills, then the organization should consider replacing the employee with one who has fewer

abilities/skills. If an employee’s abilities/skills cannot be fully used, then there will be a motivation problem.

Norms

Definition: Typical behavior in a social group or

organization.

 Norms are simply the state of actual conditions

 They can be effective or ineffective in the performance of quality work

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Some Ineffective Norms

We Have Seen at Airlines

Memorizing tasks instead of using manuals/cards

Not using torque wrenches

Troubleshooting through experience, instead of using the Fault Isolation Manual (FIM)

Deviating from maintenance manual procedures

Failing to attach “Do Not Use” tags when pulling circuit breakers and switches

Skipping functional or operational tests

Signing off for tasks not seen nor checked

Providing minimum information in shift handover log

Failing to document work not specified in the manual (e.g., loosening a clamp on a wire bundle)

Norms



The Asch studies suggest that new staff

will quickly pick up the existing norms in

their work group. If these are norms like

 Memorizing tasks instead of using manuals/cards

 Not using torque wrenches,

then new staff will quickly learn these

behaviors.

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Procedural Non-Compliance

EASA 145 requires that procedural

non-compliance be addressed. Very important!

There is an assumption that people will follow the procedure as written.

When this assumption is broken, the whole basis of the safety system is put at risk.

Maintenance requirements, therefore safety, are based almost solely on an assumption that people will follow the procedures.

Therefore, maintenance organizations should:

Not allow procedural non-compliance to become a normal behavior (norm), and

Make sure written procedures are easy to follow so that they will be used.

Signing Tasks Not Seen

Nor Checked



EASA 145 requirement to address this

issue.



New Alternate Means of Compliance

material elaborates on the meaning of

“sign-off” and the need to check or

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Signing Off Tasks

A “sign-off” is a statement by the competent person performing or supervising the work that the task or group of tasks has been correctly performed. This is a “worked by” off, not a QC inspection sign-off nor a release to service sign-sign-off.

Research has shown that many maintenance

tasks, which are carried out by workers who are not competent to sign off on their own work (e.g.,

temporary staff or trainees), are signed-off unseen by the person supervising the work.