human error in maintenance (1)

7/17/2019 Human Error in Maintenance (1)

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Human Error in Maintenance

Presented by:

Alabama & Northwest Florida Flight

Standards District Office


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Section Objectives

After you complete this section you will be

able to:

Define two different types of human error.

!plain why people commit errors.

!plain how human error affects A"#. Name the types of error pre$ention.


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Defining Human Error

!ample: %ohn dri$es into standing water and beginsto hydroplane.

. Slip ' (a$ing a good plan) but bad e!ecution.

!: %ohn *nows he should pump his bra*es) butmisses the bra*e and steps on the gas instead


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+. "ista*e ' A bad plan is performed) though

not on purpose.

!: %ohn thin*s that speeding up will gi$e

control o$er his car. (e steps on the gas.


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,. -iolation ' #he wrong procedure isperformed intentionally.

!: %ohn learned in dri$ers education classthat he should pump his bra*es in this

situation. (owe$er) %ohn heard from hisolder brother that acceleration is best) sohe steps on the gas.


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Error and Aviation Maintenance

#his section describes how human error

affects the a$iation community) a$iation

maintenance and more specifically theA"#.


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Valuejet flight !"



Machine#Human $auses for

Accidents%Airline safety has impro$ed o$er the past /

years because of:

better aircraft.

better air traffic control.

better weather prediction.



Machine#Human $auses for

Accidents% (uman error defined

byred line.

"achine error definedby yellow line.

0

20

40

60

80

100

120

1850 1900 1950 2000 2050



Human Error Estimates&%

System 0 Due to (uman rror

Airlines 1/23/0

Air #raffic 4ontrol 5/0

Ships 3/0

6rocess 4ontrol 3/0

Nuclear 6ower 1/0

7oad #ransportation 380



'able of Aviation Accident

$ausal (actors%Causal Factors (1982-

1991)

No. of

Accidents

Onoard Fatalities

4ontrolled Flight into

#errain 94F#;

,< +



'able of Aviation Accident

$ausal (actors%@round Deicing>Anti2icing 5 ,3

ind shear / ,3

?n2contained ngine Fire 55

Out of 4onfiguration #a*e2off

33

Airport @round Ops.4ontrol

+, ,3

7eBected #a*e2off 5 8,

!O!A" #94 96#9



)ntroduction to Human Error

CFor want of a nail) the shoe was lost)

for want of a shoe) the horse was lost)

for want of a horse) the rider was lost)

for want of a rider) the battle was

lost

22EenBamin Fran*lin22



Heinrich *atio

Heinrich Ratio

Fatal Accident

Non2Fatal Accident /

7eportable ncident ,/

?nsafe Acts



Active and +atent Errors

#here are two basic *inds of human errors:

acti$e errors and latent errors.

Acti$e rror ' An action that has an

immediate effect.

=atent rror ' An action that has a delayed

effect

7eason) %. 955/;. (uman rror) 4ambridge) ?G: 4ambridge 6ress.




Acti$e errors' Actions that ha$e immediateeffect. 6eople are most familiar with acti$e

errors. An e!ample of an acti$e error wouldbe a pilot belie$ing his aircraft to be muchhigher than it really is and failing to adBusthis altitude accordingly. #his error leads tothe plane crashing into a mountainside) aneffect that is felt more or less immediatelyin the system.



Active and +atent Errors%

=atent errors' Actions that ha$e delayed effect.=atent errors) on the other hand) are errors whoseeffects are delayed in time and space and may not befelt immediately. An e!ample would be an A"#neglecting to chec* a *ey bolt supporting an engine toa wing. #his bolt happens to be corroded. O$er time)the engine support wea*ens and fails altogether. (ad

the A"# not committed the latent error of neglect)the corroded bolt would ha$e been replaced and thesupport would not ha$e been compromised.




Eecause of the time delay between error and

conseHuence) latent errors and their causes

are much more difficult to trace than areacti$e errors.



Human Error in Maintenance

#he a$erage cost of an in2flight engine shutdown is

I8//)///.

#he a$erage cost of a flight cancellation is I8/)///. #he a$erage cost of a return to gate is I8)///.

#he Airline #ransport Association estimates that ground

damage costs I38/ million>year.

#he a$erage ground damage incident costs I1/)///. One Airline estimates between I182I// million>year is

wasted on error


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A Hangar e,am-le


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E,am-le: *esulting Damage

=eft2hand horiJontal stabiliJer.

7udder.

7ear doc* stands.

(angar wall.


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E,am-le: $ost (actors

"aterial

7egular and o$ertime labor.

7epair to doc* stands and hangar wall. =oss of bay during e!tra repair duration.

Delayed or third party maintenance for other aircraft.

Operational complications due to aircraft a$ailability.

n$estigation and remediation.

stimated total cost K I5//)///.


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E,am-le: $ost )m-lications

Annual airline re$enue K I+)///)///)///.

7e$enue>day K I,,)///)///.

stimated profit margin K 80

6rofit per day K I)associated costs K I5//)///.Summary: Error Consumed day of total

profit!


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'o- Seven $auses of )n.(light

Shutdo/ns. ncomplete installation 9,,0;.

+. Damage on installation 9.80;.

,. mproper installation 90;.

. Huipment not installed or missing 90;.

8. Foreign obBect damage 9


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Other Maintenance 0 *elated

$auses of )n.(light Shutdo/ns "issing parts.

ncorrect parts.

orn parts. 4areless installation of O2ring.

E2nuts not safety wired.

E2nuts wired bac*wards.

Nuts not torHued O$er torHuing.

Not loosening both ends of connections.

7eplacing tube assembly without brea*ing connections.


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'o- Seven $ommon Maintenance

Errors. ncorrect installation of components.

+. #he fitting of wrong parts.

,. lectrical wiring discrepancies 9including cross2connection;.

. =oose obBects 9tools) etc.; left in aircraft.

8. nadeHuate lubrication.


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1hy Do 1e Ma2e Errors3

L


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Mental +imits: Disassembly


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Mental +imits: *eassembly


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Definition of $ulture

Culture' A pattern of beliefs and

e!pectations shared by an organiJation and

its members.


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$ulture

hat would happen if an air carrier made

on2time departure its number one priorityL

(ow would that affect safetyL

Do you thin* management would gi$e you

the time to ser$ice an airplane the right

wayL

Do you thin* you would be pressuredL


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$ulture


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+ist of Organi4ational and +ocal

(actors%OrganiJational =ocal

#raining and selection ofpersonnel. Gnowledge and s*ill ofpersonnel.

Muality of resources asdistributed.

Muality of resources onhangar floor.

OrganiJational Structure (angar en$ironment.

Opportunities for careerde$elopment.

"orale & personalities ofemployee.


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A Human (actors Accident

Scenario%Defenses

@aps

#eamwor*

7eliable "aintenance

@ood "anagement

Ambiguous instruction9goes unchallenged;

oung F>O lets it go

"is2Budgment by senr. 4apt.

"issing component

Operational pressure

(igh wor* load.


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Error Prevention

#hree Easic Strategies


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'y-es of Prevention Design

. !clusion Design ' #he design of a component

ma*es it impossible to commit an error.

+. 6re$ention Design ' #he design of a componentma*es it difficult) but not impossible for error.

,. Fail2Safe Design ' #he design of a component

reduces the conseHuences of errors without

necessarily reducing the li*elihood of errors.


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E,am-les of Prevention Design

. !clusion design

+. 6re$ention design

,. Fail2Safe design


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$onclusion

Flying is not inherently dangerous, but

to an even greater extent than the

sea, it is terribly unforgiving of

carelessness, incapacity, or neglect

human error in maintenance (1)

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