EMSG Conference 10 October 2007AAIB Farnborough

RISK IN THE MAINTENANCE ENVIRONMENT

ROYAL AERONAUTICAL SOCIETY

ENGINEERING MAINTENANCE STANDING GROUP CONFERENCE

AAIB FARNBOROUGH, 10 OCTOBER 2007

Alan P Simmons M.Sc., C.Eng., M.R.Ae.S.

Principal Inspector of Air Accidents,

Air Accidents Investigation Branch, United Kingdom

EMSG Conference 10 October 2007AAIB Farnborough

EMSG Conference 10 October 2007AAIB Farnborough

PRESENTATION OVERVIEW

SAFETY SYSTEMS AND HUMAN PERFORMANCE

MAINTENANCE ERROR AND BUSINESS RISK

REMEDIAL MEASURES

EMSG Conference 10 October 2007AAIB Farnborough

SAFETY SYSTEMS AND HUMAN PERFORMANCE

IN MAINTENANCE

Our safety systems have evolved:

• Checking/inspecting: Quality Control

• Controlling the production process: QC, TQM

• Managing safety: MEMS, SMS

EMSG Conference 10 October 2007AAIB Farnborough

SAFETYMANAGEMENT SYSTEMS

SAFETY SYSTEMS AND HUMAN PERFORMANCE

IN MAINTENANCE

EMSG Conference 10 October 2007AAIB Farnborough

LIMITATIONS OF HUMAN PERFORMANCE

Perception and Cognitive limitations

Optical and Auditory limitations

Tunnelling and focusing

SAFETY SYSTEMS AND HUMAN PERFORMANCE

IN MAINTENANCE

Man errs as long as he strives.

Goethe

EMSG Conference 10 October 2007AAIB Farnborough

ERROR TYPE MAINTENANCE EXPERT DATA

ASSESSMENT

Skip a step 0.15 0.001Skip a task 0.026 0.001Ignore a warning/caution 0.042 0.013Intentionally deviate 0.042 0.32Improperly remove/replace 0.033 0.02Improperly repair 0.089 0.0023Incomplete installation 0.089 0.01Improperly adjust 0.09 0.1Allow/cause debris to enter 0.17 0.01

SAFETY SYSTEMS AND HUMAN PERFORMANCE

IN MAINTENANCE

Source Ostrom et al, INEEL

EMSG Conference 10 October 2007AAIB Farnborough

PROCEDURES MITIGATE RISK OF HUMAN ERROR

Clear documentationParts kitsChecklistsInspections Function checks

Even pre-flight checks

SAFETY SYSTEMS AND HUMAN PERFORMANCE

IN MAINTENANCE

EMSG Conference 10 October 2007AAIB Farnborough

WHY PROCEDURAL ERRORS UNDERMINE SAFETY: Clear documentation is useless if not used

Parts control cannot work if uncontrolled stocks are held

Independent Inspections must be truly independent

Function checks must be carried out

SAFETY SYSTEMS AND HUMAN PERFORMANCE

IN MAINTENANCE

EMSG Conference 10 October 2007AAIB Farnborough

Can your maintenance staff actually perform the required inspections?

EMSG Conference 10 October 2007AAIB Farnborough

Do you have uncontrolled small parts?

EMSG Conference 10 October 2007AAIB Farnborough

Do your engineers improvise?

EMSG Conference 10 October 2007AAIB Farnborough

Are your engineers under pressure to avoid ground runs at night?

EMSG Conference 10 October 2007AAIB Farnborough

Do your engineers sign off task cards sight unseen?

EMSG Conference 10 October 2007AAIB Farnborough

Is the Approved Data correct and is there a viable procedure to amend errors?

EMSG Conference 10 October 2007AAIB Farnborough

MAINTENANCE ERROR AND BUSINESS RISK

EMSG Conference 10 October 2007AAIB Farnborough

MAINTENANCE ERROR AND BUSINESS RISK

EMSG Conference 10 October 2007AAIB Farnborough

Most maintenance error events investigated by AAIB are INCIDENTS not ACCIDENTS

Maintenance related incidents form a larger proportion of total maintenance related events investigated by AAIB than accidents

Incidents are less spectacular but very expensive

MAINTENANCE ERROR AND BUSINESS RISK

EMSG Conference 10 October 2007AAIB Farnborough

MAINTENANCE ERROR AND BUSINESS RISK

EMSG Conference 10 October 2007AAIB Farnborough

…

MAINTENANCE ERROR AND BUSINESS RISK

EMSG Conference 10 October 2007AAIB Farnborough

MAINTENANCE ERROR AND BUSINESS RISK

Procedural deviations are at the root of many maintenance related events

Maintenance error arising from non-procedural practices incurs a dual risk to the business:

1 The risk of exposure to loss (loss of safety,earnings)

2 The risk of fines, litigation, denied insurance claims

EMSG Conference 10 October 2007AAIB Farnborough

THE COSTS OF A MAINTENANCE EVENT

Rework/re-instatement costsAdditional hangar time costsRepair costs for consequential damageMaintenance re-scheduling and knock-on delaysOperational schedule related costsCompensation costsCost of hiring a replacement aircraftBusiness costs –

obtaining and retaining market share

MAINTENANCE ERROR AND BUSINESS RISK

EMSG Conference 10 October 2007AAIB Farnborough

Recent examples from AAIB investigations into actual incidents:

A technician assembled propeller de-icer boots without the required sealant materials, which were difficult to obtain. The boot detached causing injury and damage.

A mechanic assembled a helicopter rotor head without the required shims, because the job was urgent. The helicopter suffered severe vibration and blade cracking.

After major maintenance, an engineer stamped up a number of job cards to close all remaining open panels, but not all the panels were open at the time. One of the closed panels was not properly closed and latched. The panel came off and penetrated the cabin.

EMSG Conference 10 October 2007AAIB Farnborough

How can we reduce the risk of maintenance error?By promoting:

• A culture which rewards procedural compliance…

• …and discourages violations

• Error-tolerant systems

• Reporting systems which work and are used

• An analytical approach to risk

MAINTENANCE ERROR AND BUSINESS RISK

EMSG Conference 10 October 2007AAIB Farnborough

In 1994 AAIB stated: ‘The Civil Aviation Authority should formally remind engineers of their responsibility to ensure that all work is carried out using the correct tooling and procedures, and that they are not at liberty to deviate from the Maintenance Manual but must use all available channels to consult with a design authority where problems arise; if full compliance cannot be achieved the engineer is not empowered to certify the work’.

[Airbus A320, G-KMAM AAIB Report 2/95, Safety Recommendation 94-41]

This is still the only way forward.

MAINTENANCE ERROR AND BUSINESS RISK

EMSG Conference 10 October 2007AAIB Farnborough

THANK YOU FOR YOUR ATTENTION