HUMAN FACTORS IN AIRCRAFT MAINTENANCE RELATEDACCIDENTS AND INCIDENTS

by

George Leath

A Graduate Research Project (Proposal) Submitted to the ExtendedCampus in Partial Fulfillment of the Degree of

Master of Aeronautical Science

Embry - Riddle Aeronautical UniversityExtended Campus

Houston Resident CenterApr-23

HUMAN FACTORS IN AIRCRAFT MAINTENANCE RELATEDACCIDENTS AND INCIDENTS

by

George Leath

This Graduate Research Project (Proposal)was prepared under the Direction of the candidate’s Research Committee

Member, Mr. Wesley Zubkow Instructor, Extended Campus,and the candidate’s Research Committee Chair,

Dr. Walter Sipes, Associate Professor, Extended Campus, and has been approved by the Project Review Committee. It was submitted to the

Extended Campus in Partial Fulfillment of the Degree ofMaster of Aeronautical Science

PROJECT REVIEW COMMITTEE

_____________________________Mr. Wesley ZubkowCommittee Member

_____________________________Dr. Walter SipesCommittee Chair

ii

ACKNOWLEDGEMENTS

The writer wishes to express special thanks to his Research Committee Chair,

Ph. D. and Committee Member, for their valuable guidance and inspiration

throughout the entire research process. Additional thanks to my family for their

patience, understanding, and assistance. Special thanks is due to and his

Houston Center staff for their support and guidance, without their special help

and encouragement, this study could not have been completed.

iii

ABSTRACT

Researcher: George Leath

Title: HUMAN FACTORS IN AIRCRAFT MAINTENANCE RELATED ACCIDENTS AND INCIDENTS

Institution: Embry-Riddle Aeronautical University

Degree: Master of Aeronautical Science

Year: 2003

Aviation accident statistics reveal that maintenance errors were a contributing

factor in 12% of aircraft accidents and incidents. An in-depth review of aviation

case studies indicate, that a series of human errors was allowed to form until the

accident or incident occurred. Human Factors (HF) has emerged as critical to

the safety of aviation maintenance, the industry responded by introducing HF

training. HF training has been mandated by the Federal Aviation Administration

(FAA). This research examined the effect HF training has had on the occurrence

of aviation maintenance errors and to make recommendations for future

improvements. The data was retrieved from databases maintained by the FAA

and the National Transportation Safety Board (NTSB).

iv

TABLE OF CONTENTS

Page

PROJECT REVIEW COMMITTEE ii

ACKNOWLEDGEMENTS iii

ABSTRACT iv

LIST OF TABLES vii

LIST OF FIGURES viii

I INTRODUCTION 1

Background of the problem 1

Statement of the Problem 5

Sub Problems 5

Hypothesis 6

Assumptions and Delimitations 6

Definition of Terms 7

II REVIEW OF RELEVELANT LITERATURE AND RESEARCH 8

Introduction to the Literature 8

Academic and Private Sector Participation 9

Government Involvement 10

Industry Efforts 14

Statement of the (Hypothesis or Research Question) 22

v

III RESEARCH METHOLODGY 23

Research Design 23 Research Model 23

Observation Criteria 23

Sources of Data 24

The Data Gathering Device 24

Distribution Method 24

Reliability 25

Validity 25

Treatment of Data and Procedures 25

IV RESULTS 9

V DISCUSSION 10

VI CONCLUSION 11 VII RECOMMENDATIONS 12 REFERENCES 22

APPENDICES

A BIBLIOGRAPHY 14

B PERMISSON TO CONDUCT 16

C DATA COLLECTION DEVICE (an example) 17

D TABLES 22

E FIGURES 24

vi

LIST OF TABLES

vii

LIST OF FIGURES

Figure Page

1 Aloha Airlines Accident 1

2 Typical Aircraft Maintenance Department 4

3 Typical Aviation Communications 5

4 MEDA Process Flow 17

viii

ix

CHAPTER I

INTRODUCTION

Background of the Problem

Aviation is considered one of the safest means of travel in the world today,

yet every now and then, an accident or incident occurs which shakes us out of

complacency. Aviation history abounds with descriptions of accidents and

incidents attributable to maintenance error. An in-depth review of actual aviation

case studies will reveal, time and time again, that a series of human errors (known

as a chain of events) was allowed to form until the accident or incident occurred

(Shepherd, 1991). One of the most spectacular was the Aloha Airlines accident in

Hawaii on April 28, 1988. In this event, the forward upper fuselage of the aircraft

separated in-flight from a point near the floor line (see figure 1).

Figure 1. Aloha airlines accident. Note. From Embry-Riddle Aeronautical University DCE web page, 2002

1

Passengers seated in this area were pummeled by slipstream and flailing

structural wreckage, but through a combination of extreme good fortune and pilot

skill, the airplane was landed with the unfortunate loss of one life, a flight

attendant, who was standing in the aisle at the moment the surrounding structure

disintegrated. Subsequent investigation revealed that the airplane had been

showing plenty of signs of impending structural failure but the airline’s

maintenance staff had overlooked these.

A commuter airline accident highlights the importance of communication

and work conditions in aircraft maintenance. A Continental Express Embraer

Brasilia was undergoing routine maintenance in the evening prior to its dispatch to

service the following morning. One of the tasks that was to be performed was the

replacement of the horizontal stabilizer de-ice boots. One of the boots was

successfully removed and replaced; however, the second boot installation was

only partly completed by one shift of workers. The following work shift was not

informed of the incomplete status of the boot repair. Numerous attaching screws

on the upper surface had been left out. Incoming workers examined the T-tail

surface from the ground with a flashlight, since the aircraft was being worked on in

darkness outside the hangar. Since the structure appeared to be in good order,

the aircraft was dispatched for service. In a subsequent flight the boot separated

from the stabilizer resulting in structural failure of the empennage and loss of the

aircraft with all aboard.

Following the Aloha Airlines accident, the Office of Aviation Medicine (AAM)

was tasked by the Offices of Airworthiness and Flight Standards to take a closer

2

look at aircraft maintenance Human Factors (HF) issues. A review of HF research

revealed an almost total lack of information concerning the factors that affect the

performance of Aircraft Maintenance Technicians (AMTs). Hundreds upon

hundreds of studies and reports exist related to pilot and air traffic controller

performance, but virtually nothing on mechanics and inspectors. This lack of

research is somewhat puzzling, in view of the demonstrable fact that maintenance

error can have just as devastating a result as pilot or air traffic controller error.

The AAM research program has concluded that most HF problems in aircraft

maintenance belong to one or more of the following categories (see figure 2):

The worker

The workplace

Communication

Training

Figure 2. Typical aircraft maintenance department. Note. From Embry-Riddle Aeronautical University DCE web page, 2002

3

“Accident statistics reveal that maintenance errors were a contributing

factor to the chain of events in 12% of major airplane accidents many, if not most,

of these accidents involved some degree of human error “(Shepherd, 1991).

When we look at an aviation accident or incident where maintenance had a

contributing link in the chain of events we sit back and wonder how could this have

happened with all the Regulatory Compliance Programs that are imposed on the

industry today. In some cases the error itself was the primary cause of the

accident, whereas in other cases, the resulting maintenance discrepancy was just

one link in the chain of events that led to the accident. As HF has emerged as

critical to the safety of maintenance, a major response by the industry has been to

introduce HF training. The natural response is "If HF are such a problem, then let's

train our technicians in HF" (Cronie, 1999). HF training, commonly called

Maintenance Resources Management (MRM), has been developed by airlines,

manufacturers and training organizations and has been mandated by the Joint

Aviation Authority / Federal Aviation Administration (JAA / FAA). The industry is

committed to training as a remedy for human factors problems. “If we can break

the chain of events at the maintenance level, the accident will not likely happen”

(Shepherd, 1991). A further study of such cases shows that there could have

been safety nets put in place in the maintenance department to prevent this

incident from ever happening. HF re-emphasizes the requirements for the

workforce to create safety nets in the workplace.

At a time when aviation organizations increasingly expect employees to

work with minimal supervision and to show more initiative, competent

4

communication skills are becoming a must. Without communication in

maintenance, not a single aircraft could safely leave the ground. “The type and

level of communication that must go on among operators, manufacturers,

designers, records keepers, passengers, pilots, dispatchers, trainers, students, the

public, government authorities (the list is seemingly endless) is positively mind-

boggling” (Shepherd, 1991), as shown in figure 3.

Figure 3. Basic aviation communication. Note. From Galaxy scientific corporation, 2002.

Statement of the Problem

In the days of the DC-3, there were only a few airplanes and their maintenance

requirements were, by today’s standards, decidedly “low-tech” (Cronie, 1999). “Today HF

related to some type of maintenance error has contributed to 12% of all major aircraft

accidents / incidents” (Cronie, 1999). This research is interested in determining exactly what

impact the mandated Aviation Safety Research Act of 1988, (which, specifically authorized

5

research to be performed by AAM) has had on maintenance error in aviation accidents and

incidents. AAM’s goal was to reduce maintenance-related accidents and incidents resulting

from human error by 20% by the year 2003.

Statement of the Hypothesis

Null (Ho) - The introduction off MRM into aviation maintenance has reduced

maintenance human error related aircraft accidents and incidents.

Alternate (Ha) – The introduction of MRM Training in aviation maintenance has not

reduced maintenance human error related aircraft accidents and incidents.

Assumptions

This research is being accomplished for the sole purpose of fulfilling the

requirements of the MAS program at Embry Riddle Aeronautical University; no

outside funding will either be provided or solicited. It will be completed in a timely

manner based on the researchers resources and capabilities, and university

guidelines. All incidents and accidents were investigated by the NTSB or the FAA,

and all data facts will be presented unbiased, and as they where discovered.

Delimitations

The data collected will be from United States General Aviation and United

States Commercial Air Carriers only. Foreign or military data will not be included in

this research; this will be a study of data submitted before and after MRM training.

6

Definition of TermsA/C Aircraft

AAIB Air Accidents Investigation Branch

AAM Office of Aviation Medicine

AANC (US) Ageing Aircraft Inspection Validation Center

AAR Office of Aviation Research

AD Airworthiness Directive

ADAMS (Human Factors) in Aircraft Dispatch and Maintenance

AIDS Accident and Incident Data System

AMC Acceptable Means of Compliance (for JARs)

AME Aircraft Maintenance Engineer

AMPOS Aircraft Maintenance Procedure Optimization System

AMT Aircraft Maintenance Technician

AOG Aircraft On the Ground

ASRS Aviation Safety Reporting System

ATA Air Transport Association of America

ATC Air Traffic Control

AWN Airworthiness Notice

BASIS British Airways Safety Information System

BASIS MEI BASIS Maintenance Error Investigation

BCAR British Civil Airworthiness Requirements

CAA (UK) Civil Aviation Authority

CAMC Canadian Aviation Maintenance Council

7

CARMAN Consensus Based Approach to Risk Management

CASA (Australian) Civil Aviation Safety Agency

CBT Computer Based Training

cd candela

CEO Chief Executive Officer

CFS Chronic Fatigue Syndrome

CMI Computer Managed Instruction

CRM Crew Resource Management

DDA Document Design Aid

DOD Department of Defense

DOE Department of Energy (USA)

DOT Department of Transportation

ERAU Embry Riddle Aeronautical University

ERNAP Ergonomics Audit Program

FAA Federal Aviation Administration

FAR Federal Aviation Regulation

FEMA Failure Modes and Effects Analysis

fL footLambert

FODCOM Flight Operations Department Communication

GAIN Global Aviation Information Network

HAZOP Hazard and Operability study/ assessment

HF Human Factors

8

HFRG (UK) Human Factors in Reliability Group

HRA Human Reliability Assessment

HSE (UK) Health and Safety Executive

IBT Internet Based Training

ICAO International Civil Aviation Organization

IEM Interpretative/ Explanatory material (for JARs)

IES (US) Illuminating Engineering Society

IFA International Federation of Airworthiness

IMIS Integrated Maintenance Information System

JAA Joint Aviation Authority (European)

JAR Joint Aviation Requirement

LAE Licensed Aircraft Engineer

lm lumen

LOFT Line Oriented Flying Training

lux lumens/m²

MARSS Maintenance and Ramp Safety Society

MEDA Maintenance Error Decision Aid

MEDA Maintenance Engineering Decision Aid

MEMS Maintenance Error Management System

MEMS FMS Maintenance Error Management System Free MEDA

Software

MESH Maintenance Engineering Safety Health

9

MHFWG JAA Maintenance Human factors Working Group

MM Maintenance Manual

MOE Maintenance Organization Exposition

MOR (UK) Mandatory Occurrence Report

MRM Maintenance Resource Management

NAA National Aviation Authority

NAS National Airspace System

NASA National Aeronautics Space Administration

NASA TLX NASA Task Loading Index

NASDAC National Aviation Safety Data Analysis Center

NDI Non-Destructive Inspection

NDT Non-Destructive Testing

NPA Notice of Proposed Amendment (for JARs)

NTSB National Transportation Safety Board

OJT On-the-Job Tuition

OSHA Occupational Safety and Health Administration

PC Personal Computer

PRA Probabilistic Risk Assessment

PSA Probabilistic Safety Assessment

R&D Research and Development

REM Random Eye Movement

ROI Return on Investment

10

SA Situational Awareness

SB Service Bulletin

SHEL Model Software, Hardware, Environment, Liveware

SMM Shift Maintenance Manager

SMS Safety Management Systems

STAMINA (Human Factors) Safety Training for the Aircraft Maintenance

Industry

SWAT Subjective Workload Assessment Technique

TC holder Aircraft Type Certificate holder

TGL Temporary Guidance Leaflet (for JARs)

TQM Total Quality Management

TWA Time Weighted Average sound level

UK HFCAG UK Human Factors Combined Action Group

UK OTG UK Operators’ Technical Group

UK RAF SAM UK Royal Air Force School of Aviation Medicine

VIRP (US) Visual Inspection Research Program

11

CHAPTER II

REVIEW OF RELEVELANT LITERATURE AND RESEARCH

Introduction to the Literature

Aircraft accidents and incidents are events that involve direct or potentially

direct effects on the safety of aircraft operations and of persons involved in those

operations. Accidents result in death or serious injury to a person in, upon, or

about the aircraft, or in substantial damage to the aircraft itself. Incidents are less

serious events "that affect or could affect the safety of operations." (FAA, 1996b).

The literature review will examine various studies of HF related to aviation

maintenance, which is one of the most promising means of increasing aviation

safety (Shepherd, 1997).

In the following studies and or research the authors attempt to explore how

HF tries to identify and reduce the chances for human error through improvements

in design and training. HF related aviation accidents and incidents remain

subjects of great public concern. Despite the aerospace industry's success at

developing ever more sophisticated and reliable technology, the proportion of

human error-related accidents and incidents remains remarkably constant (Kraus,

1998). This fact, combined with expected growth rates and the requirement to

12

increase productivity, has resulted in considerable attention to HF research and

application programs over the last several years (Shepherd, 1997). Valuable

programs in aviation human factors have been underway for many years at the

FAA, NASA, and DOD, as well as in academic and industry sectors.

Academic and Private Sector Contribution

Embry-Riddle Aeronautical University (ERAU) offers a workshop on HF In

Aircraft Maintenance, the workshop focuses on the variety of HF that come into

play in the course of an AMT’s work. The workshop is specifically for aircraft

technicians, and their supervisors. Aircraft maintenance is a training orientated

industry. General and specific competencies are developed through basic and

type training. These competencies are enhanced and updated through continuous

training. If an inadequacy is identified, a new type of aircraft is purchased or new

maintenance techniques developed, appropriate courses are sought out for AMT,s

(Cronie, 1999).

As HF has emerged as critical to the safety of maintenance, a major

response by the industry has been to introduce HF training. The natural response

is "If HF are such a problem, then let's train our technicians in human factors."

(Cronie, 1999). HF training has been developed by airlines, manufacturers and

training organizations and has been mandated by the JAA and FAA. The industry

is committed to training as a remedy for HF problems (Cronie, 1999). A review of

HF research by AAM, revealed an almost total lack of information concerning the

factors that affect the performance of AMT, s. “Hundreds upon hundreds of

13

studies and reports exist related to Pilots and Air Traffic Controllers (ATC,s)

performance, but virtually nothing on mechanics and inspectors. This lack of

research is somewhat puzzling, in view of the demonstrable fact that maintenance

error can have just as devastating a result as pilot or air traffic controller error”

(Shepherd, 1991).

The AAM research program has concluded that most human factors

problems in aircraft maintenance belong to one or more of the following

categories:

The Worker

Aircraft maintenance is frequently performed at night because most flights are

conducted during the day. Physiologically and mentally, we are most alert during

daytime hours and prefer to rest or sleep during nighttime hours. Many people find

it difficult to disturb this pattern. When they are required by their jobs to sleep

during the day and work at night, work performance deficits frequently ensue. This

effect can clearly have serious implications for aviation safety. The result can be a

fatigued technician with a greater tendency toward work error. AAM research is

evaluating the effects of shift work and fatigue on technician performance and has

developed software that allows maintenance managers to assess the “degree of

difficulty” of tasks and to make appropriate work assignments.

The workplace

Aircraft maintenance workplaces can range from climate-controlled, well-lit,

relatively quiet hangars to nighttime, outdoor, noisy ramps in cold, rainy weather.

Obviously, the first set of conditions is preferred to the second because it is likely

14

to foster error-free and efficient work. On the other hand the conditions in the

second example, individually or collectively will likely impair technician

performance. Noise on ramps from aircraft operations, or in hangars from riveting

or power unit operation, can be distracting, have obvious health implications, may

result in heightened response of the human autonomic nervous system, and often

increase fatigue. Lighting in aircraft maintenance, particularly on inspection tasks,

can mean the difference between flaw detection and non-detection; between a

correct or incorrect repair. Flashlights are frequently seen in aircraft maintenance.

They can be very useful in illuminating areas that are not lit by ambient lighting,

but they also often encumber the use of one hand, making it difficult to perform

some tasks. Also, flashlights often lack the brightness needed for some jobs.

Better solutions entail use of portable lighting that can be easily moved or affixed

to an adjacent structure.

Communication

In the days of the DC-3, maintenance communication was relatively

straightforward. There were only a few airplanes and their maintenance

requirements were, by today’s standards, decidedly “low-tech.” A single recent

example shows how much change has occurred. In 1988, Boeing Commercial

Airplane Company’s publication activity included maintaining 1,126 active manuals

for 5,300 airplanes and 425 worldwide operators. This amounts to nearly 20 million

page sets, with each manual being revised about every 120 days. Boeing

publishes a paper stack every year that exceeds the height of Mt. Everest. Most, if

not all, major airframe manufacturers now produce their maintenance

15

documentation in electronic form. A technician can now access maintenance

information from tape or disc and present it on a video terminal. With these recent

enhancements in computer capabilities, it is now possible, for example, to perform

full text searches for key words, to display information one page at a time, or

jumping through several pages at a time, to have the computer lead the user to

related information located in several different sources, or to use the system for

on-line training and job-aiding. AAM is working with a number of airlines to develop

and evaluate some of these innovative electronic systems under actual working

conditions. AAM is evaluating PEN-Based computer systems in aircraft

maintenance and for use by FAA Aviation Safety Inspectors. These systems allow

rapid access to stored information such as regulations, airworthiness directives,

repair procedures, and parts lists. PEN computers also have on-screen written

input capabilities, which with a special stylus and hand writing recognition software

permit the user to file reports, fill out forms, and provide input to main frame

computer data bases. By some estimates, paperwork now consumes 25% of

available technician and inspector time.

If these new systems could reduce this odious communication burden by

even a few percent, there would be dramatic improvements in the bottom-line

performance of FAA inspection and airline maintenance organizations by making

this time available for the work the technicians and inspectors are hired for. AAM

research on these systems is providing a head start to airlines and FAA on

automating systems that are currently heavily paper oriented.

16

Training

New training technologies are being studied by AAM along with the new

communication technologies described in the previous paragraph. These new

training methods can be used to supplant or supplement on-the-job-training at the

work site, or more formal classroom and laboratory training, as found in technician

training schools. New training technology might be loosely defined as training with

computers. This can include such methods as time-tested computer-based

instruction, interactive videodisc, computer-controlled simulators, computer-

controlled real equipment, and computer-based testing.

AAM’s research into aircraft maintenance human factors is one of only a few

leading-edge projects worldwide in this area. It is already paying dividends through

heightened awareness of the importance of technician performance to flight safety.

However, the real payoffs will come later, when the AAM-developed systems,

tools, and technology are in regular use within FAA and the airline industry. AAM

currently has ongoing research tasks in each of these areas.

Government Involvement

The Human Factors Division (AAR-100) of the FAA provides scientific and

technical support for the civil aviation human factors research program and for

human factors applications in acquisition, certification, regulation, and standards. It

develops and assures implementation of human factors policies, regulations,

programs, and procedures, which promote the safety and productivity of the

National Airspace System (NAS). It also formulates and manages the aviation

17

human factors research program and provides human factors support to

acquisition and regulatory activities. The U.S. civil air carrier fleet requires a well-

trained and accountable maintenance workforce to provide continuing safe and

reliable air transportation. However, acquiring this workforce is a growing problem

due to a shortage of Aviation Maintenance Technicians (AMT, s) to support an

ever-increasing number of aircraft. The linchpin of this system is the human,

recognizing this the FAA has pursued human factors research by placing an

increased emphasis on technical and human factors training. Previously, the

training concerns of the aircraft maintenance environment had focused on

technical / procedural skills. But, these training issues need to be supplemented

with maintenance human factors training at the same level and with the same

emphasis as crew resource management (FAA, 1996), (human factors training for

the flight deck crews).

The NTSB maintains a database on aircraft accidents and serious incidents,

and also publishes hardcopy reports on the most serious accidents. The FAA

maintains the Accident and Incident Data System (AIDS), which contains

information on incidents, and also maintains specialized databases on specific

types of incidents. Specialized FAA incident databases include human factor

issues such as Pilot Deviations, Near Midair Collisions, and Operational and

Maintenance Errors. In addition, the Aviation Safety Reporting System (ASRS)

database contains voluntary reports of safety incidents. The FAA collects and

reports (e.g., FAA (1996b) a variety of data that can be used to measure or

evaluate air carrier safety and the safety of the aviation system. Most data

18

reported today looks at safety levels in a highly aggregated format. Databases

containing information on NTSB aviation accident reports and safety

recommendations are available online at the FAA's Office of System Safety

homepage. Monthly flight hours and accident and incident rates for large air

carriers, commuters, air taxis, general aviation, and rotorcraft are also available in

the Aviation System Indicators at this web site. Descriptive information is available

for individual airlines from the carriers themselves and in the Vital Information

Subsystem. There are a wide variety of aviation events that are categorized as

aviation incidents; information on these is available at FAA's National Aviation

Safety Data Analysis Center (NASDAC) system. All of these accident and incident

data are available to the public. Because accidents and incidents, once reported

and investigated, are believed to represent a relatively unambiguous record of

unfavorable safety events, they are the safety measures most commonly used by

researchers for analyzing changes in aviation safety over time and differences

among carriers and groups of carriers. However, the raw data on accidents and

incidents must be converted to accident and incident rates before it can

legitimately be used for making comparisons about safety over time, among

groups of carriers, or among individual carriers. This type of conversion, is called

normalization and some observers have suggested that the classification scheme

for aviation accidents used by reporting agencies is needlessly arcane, and the

Federal Aviation Authorization Act of 1996 directs the NTSB, in conjunction with

FAA, to develop a more comprehensible and refined classification of accidents

involving fatalities, injuries, or substantial damage. (Congress House, 1996).

19

The NTSB has recently responded with a proposed classification format that

addresses these concerns, (NTSB, 1996). Computation of an accident or incident

rate requires normalizing information about the level of exposure to risk. For

comparative purposes, it is essential that accident and incident data be normalized

in some way, since the system's exposure to risk changes over time. Accident

and incident rates commonly reported to the public by FAA, the NTSB, and

intermediaries such as the media and consumer groups thus combine event data-

accident counts and incident counts-with exposure data to provide a measure of

the frequency with which events have occurred. This study will try and relate the

maintenance department and associated human factors into the accident and

incident rates.

Industry Efforts

As a result of the 1997 merger with McDonnell Douglas, the Maintenance

Error Decision Aid (MEDA) process offered by Boeing is now available to

operators of Douglas-designed commercial airplanes and their maintenance

organizations (Allen, Rankin, and Sargent, 1998) Since its introduction two years

ago, a growing number of maintenance organizations for Boeing-designed

airplanes have adopted MEDA, which is a tool for investigating the factors that

contribute to maintenance errors. MEDA provides a comprehensive approach for

conducting thorough and consistent investigations, determining the factors that

lead to an error, and making suggested improvements to reduce the likelihood of

future errors. Maintenance errors cost operators of commercial airplanes millions

of dollars each year in rework and lost revenue, and present potential safety

20

concerns. For example, aviation industry studies indicate that as many as 20

percent of all in-flight engine shut downs and up to 50 percent of all engine-related

flight delays and cancellations can be traced to maintenance error, Allen et al.

(1998).

In response, Boeing developed the MEDA process to help maintenance

organizations identify why these errors occur and how to prevent them in the

future. Successful implementation of MEDA requires an understanding of the

following:

The MEDA Philosophy

Traditional efforts to investigate errors are often aimed at identifying the employee

who made the error. The usual result is that the employee is defensive and is

subjected to a combination of disciplinary action and recurrent training. Because

retraining often adds little or no value to what the employee already knows, it may

be ineffective in preventing future errors. In addition, by the time the employee is

identified, information about the factors that contributed to the error has been lost.

Because the factors that contributed to the error remain unchanged, the error is

likely to recur, setting what is called the "blame and train", Allen et al., cycle in

motion again. To break this cycle, the maintenance organization's MEDA

investigators learn to look for the factors that contributed to the error, rather than

the employee who made the error. The MEDA philosophy is based on these

principles:

21

positive employee intent.

Maintenance technicians want to do the best job possible and do not make errors

intentionally). Contribution of multiple factors (a series of factors contributes to an

error). Manageability of errors (most of the factors that contribute to an error can

be managed). This principle is key to a successful investigation. Traditional

"blame and train" Allen et al., investigations assume that errors result from

individual carelessness or incompetence. Starting instead from the assumption

that even careful employees can make errors, MEDA interviewers can gain the

active participation of the technicians closest to the error. When technicians feel

that their competence is not in question and that their contributions will not be

used in disciplinary actions against them or their fellow employees, they willingly

team with investigators to identify the factors that contribute to error and suggest

solutions. By following this principle operators can replace a negative "blame and

train" pattern with a positive "blame the process, not the person" (Allen et al)

practice.

contribution of multiple factors.

Technicians who perform maintenance tasks on a daily basis are often aware of

factors that can contribute to error. These include information that is difficult to

understand, such as work cards or maintenance manuals; inadequate lighting;

poor communication between work shifts; and airplane design. Technicians may

even have their own strategies for addressing these factors. One of the objectives

of a MEDA investigation is to discover these successful strategies and share them

with the entire maintenance operation.

22

manageability of errors.

Active involvement of the technicians closest to the error reflects the MEDA

principle that most of the factors that contribute to an error can be managed.

Processes can be changed, procedures improved or corrected, facilities

enhanced, and best practices shared.

Because error most often results from a series of contributing factors, correcting or

removing just one or two of these factors can prevent the error from recurring.

The MEDA Process

To help maintenance organizations achieve the dual goals of identifying

factors that contribute to existing errors and avoiding future errors, Boeing initially

worked with British Airways, Continental Airlines, United Airlines, a maintenance

workers' labor union, and the U.S. Federal Aviation Administration, Allen et al. The

result was a basic five-step process for operators to follow (see figure 4).

23

EVENT OCCURS

Investigation reveals event caused by maintenance error

DECISION

INVESTIGATION

Determine who made the error Interview responsible personnel

- Find contributing factors- Get ideas for progress improvement

Follow up to obtain additional contributing factors and information

Add to maintenance error database

PREVENTION STRATEGIES

Make process improvements based on contributing factors

- Based on this event- Based on analysis of data for

multiple events

FEEDBACK

Provide feedback to all employees affected by process improvements

Figure 4. MEDA process flow. Note. From the Boeing company 1998

event.

An event occurs, such as a gate return or air turn back. It is the responsibility of

the maintenance organization to select the error-caused events that will be

investigated.

decision.

After fixing the problem and returning the airplane to service, the operator makes a

decision: Was the event maintenance-related? If yes, the operator performs a

MEDA investigation.

investigation.

Using the MEDA results form, the operator carries out an investigation. The

trained investigator uses the form to record general information about the airplane,

when the maintenance and the event occurred, the event that began the

investigation, the error that caused the event, the factors contributing to the error,

and a list of possible prevention strategies.

prevention strategies.

The operator reviews, prioritizes, implements, and then tracks prevention

strategies (process improvements) in order to avoid or reduce the likelihood of

similar errors in the future.

Feedback.

The operator provides feedback to the maintenance workforce so technicians

know that changes have been made to the maintenance system as a result of the

24

MEDA process. The operator is responsible for affirming the effectiveness of

employees' participation and validating their contribution to the MEDA process by

sharing investigation results with them. MEDA is a long-term commitment, rather

than a quick fix. According to Dr. Jim Reason, professor of psychology at the

University of Manchester, MEDA is "a good example of a measuring tool capable

of identifying accident-producing factors before they combine to cause a bad

event",

Management Resolve.

The resolve of management at the maintenance operation is key to

successful MEDA implementation. Specifically, after completing a program of

MEDA support from Boeing, managers must assume responsibility for the

following activities before starting investigations:

1. Appoint a manager in charge of MEDA and assign a focal organization.

2. Decide which events will initiate investigations.

3. Establish a plan for conducting and tracking investigations.

4. Assemble a team to decide which prevention strategies to implement.

5. Inform the maintenance and engineering workforce about MEDA before implementation.

MEDA is a long-term commitment, rather than a quick fix. Operators new to

the process are susceptible to "normal workload syndrome." This occurs once the

enthusiasm generated by initial training of investigation teams has diminished and

the first few investigations have been completed. In addition to the expectation that

they will continue to use MEDA, newly trained investigators are expected to

25

maintain their normal responsibilities and workloads. Management at all levels can

maintain the ongoing commitment required by providing systematic tracking of

MEDA findings and visibility of error and improvement trends.

Implementing MEDA

Many operators have decided to use MEDA initially for investigations of

serious, high-visibility events, such as in-flight shut downs and air turn backs. It is

easy to track the results of such investigations, and the potential "payback" is very

noticeable. In contrast, according to David Hall, deputy regional manager in the

British Civil Aviation Authority (CAA) Safety Regulation Group, a high-visibility

event may not present the best opportunity to investigate error. The attention of

operators' upper management and regulatory authorities could be intimidating to

those involved in the process. In addition, the intensity of a high-level investigation

may generate too many possible-contributing factors to allow a clear-cut

investigation of the event. Hall has recommended that operators look at the

broader potential for improvement by using MEDA to track the cumulative effects

of less-visible errors. Providing management visibility of the most frequently

occurring errors can, in the long run, produce profound improvements by

interrupting the series of contributing factors. According to Dr. Jim Reason,

professor of psychology at the University of Manchester, MEDA is "a good

example of a measuring tool capable of identifying accident-producing factors

before they combine to cause a bad event."

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The Benefits of MEDA

About 60 operators have already implemented some or all of the MEDA

process. Participating airlines have reported several benefits, including the

following improvements:

A 16 percent reduction in mechanical delays.

Revised and improved maintenance procedures and airline work

processes.

A reduction in airplane damage through improved towing and headset

procedures.

Changes in the disciplinary culture of operations.

Elimination of an engine servicing error by purchasing a filter-removal tool

that had not previously been available where the service was being

performed.

Improvements in line maintenance workload planning.

A program to reduce on-the-job accidents and injuries based on the MEDA

results form and investigation methods.

The MEDA process offered by Boeing continues to help operators of airplanes

identify what causes maintenance errors and how to prevent similar errors in the

future. Because MEDA is a tool for investigating the factors that contribute to an

error, maintenance organizations can discover exactly what led to an error and

remedy those factors. By using MEDA, operators can avoid the rework, lost

revenue, and potential safety problems related to events caused by maintenance

errors.

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Statement of the (Hypothesis or Research Question)

Recently it has been more widely acknowledged that aircraft maintenance requires

human factors resources like with those that have been applied to other aspects of

aviation. The general causes of human error and the means for error prevention,

originate in basic human capabilities, limitations and training (Royal Aeronautical

Society, 1991). In aircraft maintenance there is a small margin for error, for a set

of tasks done day in and day out, a set of tasks that can determine the outcome of

hundreds of passengers. To the AMT, these tasks can become routine causing

them to inadvertently skip steps in a maintenance procedure. This research is

concerned with past statistical studies that show that 12% of aircraft accidents and

incidents involved some form of human factor error. The Aviation Safety Research

Act of 1988 specifically authorizes research to be performed by the Office of

Aviation Medicine. It’s goal was to reduce maintenance-related accidents and

incidents resulting from human error by 20% by the year 2003, by implementing

Maintenance Resource Management (MRM) training curricula and techniques.

This research will collect data on major accidents and incidents for a prescribed

period to determine exactly what affect MRM training has had on human error

elated aircraft accidents and incidents.

CHAPTER III

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RESEARCH METHOLOGY

Research Design

The research design will be a Time – Series Experiment consisting of making a

series of observations of aviation accident and incident investigation data

contained in government databases.

Research Model

The study is intended to develop and validate an observation instrument that

assesses the affect Human Factors Training (MRM) has had on the frequency of

maintenance error occurrences in aviation maintenance related accident and

incident probable cause data. Three year observations will be made before the

implementation of MRM, and an additional three year observations will be

conducted after MRM was officially introduced and a comparison will be made of

the results.

Observation Criteria

The Aviation Safety Research Act of 1988 specifically authorizes research to be

performed by the Office of Aviation Medicine. It’s goal was to reduce

maintenance-related accidents and incidents resulting from human error by 20%

by the year 2003. Creation and distribution of MRM prototype training materials

for airline use were developed, implemented, evaluated and distributed by 1998

and beyond as requirements dictate. Observations will be taken three years prior

to implementation of MRM (1988) and the three years prior to 2003.

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Sources of Data

The observation data will be taken from The NTSB aviation accident database

which contains information from 1962 and later about civil aviation accidents and

incidents within the United States, its territories and possessions, and in

international waters. Generally, a preliminary report is available online within a few

days of an accident. Factual information is added when available, and when the

investigation is completed, the preliminary report is replaced with a final

description of the accident and its probable cause. Full narrative descriptions may

not be available for dates before 1993, cases under revision, or where NTSB did

not have primary investigative responsibility.

The Data Gathering Device

The author will utilize a computerized approach of collecting and organizing the

data, the data will be extracted from NTSB, and FAA accident / incident

investigation data basses and organized into spreadsheets or tables designed to

test the stated hypothesis. The world wide web, ERAU’s library resources, and

local public libraries will be the sources of information.

Reliability

All accidents / incidents included in the observations will include NTSB / FAA ID

numbers and dates to ensure data can be linked to an actual accident and for

follow up research purposes.

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Validity

Factors such as:

The researcher's holds an FAA airframe power-plant mechanic certificate and

has 25 plus years in aviation maintenance, both as an Inspector and Mechanic.

The strict methodology used to gather, organize, test, and conduct the

experiment enhanced the validity of this study and the fact that the data was

retrieved from official accident and incident investigations.

Treatment of Data and Procedures

All data will be retrieved from government data basses and will show the human

errors involved in aircraft accidents / incidents before and after MRM was

introduced into the system.

 

CHAPTER IV

RESULTS

The results of this experiment are described in the following summary tables, the

raw data is contained in tables located in Appendix D. The NTSB concluded

10,099, aviation investigations from 1983 to 1985 of these, 9732 were accidents

and 367 were incidents. were contributed to some sort of maintenance error.

This constituted ___% of all aviation accidents/incidents involving US registered

aircraft investigated by the NTSB for this period, see tables below.

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Table .1 Accidents/Incidents investigated by the NTSB 1983 - 1985

Table 2 Maintenance error related accidents/Incidents by category 1983-1985.

TOTAL ACCIDENTS

MAINTENANCE ERROR ACCIDENT

TOTAL INCIDENTS

MAINTENANCE ERROR INCIDENT TOTAL

91 – General Aviation

103 - Ultra light

121 – Air Carrier

133 – Rotorcraft Ext. Load

135 – Air Taxi & Commuter

137 - Agricultural

Table .3 Accidents/Incidents investigated by the NTSB 2000-2002.

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Table 4 Maintenance error related accidents/incidents by category 200-2002.

CFR14 - PART TOTAL ACCIDENTS

MAINTENANCE ERROR ACCIDENT

MAINTENANCE ERROR INCIDENT

TOTAL

91 – General Aviation

103 - Ultra light

121 – Air Carrier

133 – Rotorcraft Ext. Load

135 – Air Taxi & Commuter

137 - Agricultural

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CHAPTER V

DISCUSSION

Maintenance Resource Management (MRM) has become an umbrella term that has yet to

be clearly defined.  Some current MRM programs may parallel the Crew Resource

Management (CRM) programs used for improving team communication and performance

in the cockpit.  By defining resource management for maintenance and investigating

related issues, this research will develop guidelines and related training and reference

materials for MRM through extensive cooperation with the airline industry. Error

reduction is a key activity for the research program.  The program seeks to develop

methodologies or techniques to proactively minimize aircraft maintenance errors and

enhance safety.  General areas for research include error classification, identification,

mitigation, and reduction. Aircraft maintenance human factors research is particularly

critical for improving aviation safety.

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CHAPTER VI

CONCLUSION

To meet these challenges without sacrificing safety, individual technician responsibilities and skill levels must increase.  The industry must work together to ensure that workers become more qualified and that maintenance tasks and procedures are adapted to meet human capability.  Attention to human factors in aircraft maintenance will ensure not only continuing performance enhancement of the technician workforce, but also continuing flight safety.

The research program has emerged as the most significant program of its kind related to human factors in aviation maintenance.  The aviation industry, the Department of Defense, national and international organizations, and governments around the world participate in the annual conference and use the products and reports that the program generates each year.

35

The success of the program is based on the commitment to the application of solid scientific principles to deliver pragmatic solutions.  The research shall continue to be driven by user requirements.  The research shall continue to use the aviation maintenance environment as the most important daily laboratory to conceptualize, design, develop, implement, and test procedures and products to enhance human performance.

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CHAPTER VII

RECOMENDATIONSIt is important that all errors are reported, especially those which jeopardise aircraftairworthiness or cause unacceptable economic harm to the Company, so thateffective remedial action can be taken.All levels of staff must be encouraged to report all errors to their supervisor or linemanager immediately after they occur. Once the error has been reported theemployee concerned must clearly state how they wish the error to be investigatedand reviewed. If they decide to use the Engineering and Maintenance Mishap Policythis must be confirmed in writing.Once a decision has been made to use the Engineering and Maintenance MishapPolicy the supervisor (or member of management) will then collect all available datarelating to the error, i.e. details of the staff concerned, the time and date of the error,the airframe worked on, the type of error made and any other pertinent details andimmediately forward these to the Engineering Manager.

37

REFERENCES

Allen, J., Rankin, B., Sargent, B. (1998). Maintenance human factors. The

Boeing Company. Retrieved February 17, 2003, from

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html

Cronie, S (1999). Human factors training in aircraft maintenance. Research fellow

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Kraus, D. C. (1998). Proceedings of the Human Factors and Ergonomics

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Minter, B. (2002). Human factors in aviation maintenance work shop. Retrieved

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Html

Rivera, G. A. (1991). Human factors issues in interactive electronic technical

Manuals for aircraft maintenance.

Shepherd, W. T. (1991). Human factors issues in aircraft maintenance. FAA. The

federal air surgeon’s medical bulletin, Washington, D.C.

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Shepherd, W. T. (1997). Proceedings of the Human factors and ergonomics

Society ... Annual Meeting, Santa Monica; Vol. 2; pg. 1152, 2 pgs

Shepherd, W. T., W. B. Johnson, C. G. Drury, and D. Berninger. (1991). Human

Factors in Aviation Maintenance. Phase one: Progress report. Federal

Aviation Administration, Office of aviation medicine report AM-91/16.

Washington D.C.

Skormin, V. A., Gorodetski, V. I., & Popyack, L. J., Factors in aircraft accidents.

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maintenance. One day conference London, UK.

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APPENDIX A

BIBLIOGRAPHY

American Psychological Association (2001). Publication manual of the American

Psychological Association(5th ed.). Washington, DC:

N

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APPENDIX C

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