ROYAL AERONAUTICAL SOCIETY
ENGINEERING MAINTENANCE STANDING GROUP
CONFERENCE
AAIB FARNBOROUGH, 10 OCTOBER 2007
RISK IN THE MAINTENANCE
ENVIRONMENT
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 2007
AAIB Farnborough
EMSG Conference 10 October 2007
AAIB Farnborough
PRESENTATION OVERVIEW
SAFETY SYSTEMS AND HUMAN PERFORMANCE
MAINTENANCE ERROR AND BUSINESS RISK
REMEDIAL MEASURES
EMSG Conference 10 October 2007
AAIB 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 2007
AAIB Farnborough
SAFETY SYSTEMS AND HUMAN PERFORMANCE
IN MAINTENANCE
SAFETY
MANAGEMENT
SYSTEMS
EMSG Conference 10 October 2007
AAIB Farnborough
SAFETY SYSTEMS AND HUMAN PERFORMANCE
IN MAINTENANCE
LIMITATIONS OF HUMAN PERFORMANCE
Perception and Cognitive limitations
Optical and Auditory limitations
Tunnelling and focusing
Man errs as long as he strives.
Goethe
EMSG Conference 10 October 2007
AAIB Farnborough
SAFETY SYSTEMS AND HUMAN PERFORMANCE
IN MAINTENANCE
ERROR TYPE
Skip a step
Skip a task
Ignore a warning/caution
Intentionally deviate
Improperly remove/replace
Improperly repair
Incomplete installation
Improperly adjust
Allow/cause debris to enter
MAINTENANCE
DATA
0.15
0.026
0.042
0.042
0.033
0.089
0.089
0.09
0.17
EXPERT
ASSESSMENT
0.001
0.001
0.013
0.32
0.02
0.0023
0.01
0.1
0.01
Source Ostrom et al, INEEL
EMSG Conference 10 October 2007
AAIB Farnborough
SAFETY SYSTEMS AND HUMAN PERFORMANCE
IN MAINTENANCE
PROCEDURES MITIGATE RISK OF HUMAN ERROR
Clear documentation
Parts kits
Checklists
Inspections
Function checks
Even pre-flight checks
EMSG Conference 10 October 2007
AAIB Farnborough
SAFETY SYSTEMS AND HUMAN PERFORMANCE
IN MAINTENANCE
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
EMSG Conference 10 October 2007
AAIB Farnborough
Can your maintenance staff actually perform the
required inspections?
EMSG Conference 10 October 2007
AAIB Farnborough
Do you have uncontrolled small parts?
EMSG Conference 10 October 2007
AAIB Farnborough
Do your engineers improvise?
EMSG Conference 10 October 2007
AAIB Farnborough
Are your engineers under pressure to avoid
ground runs at night?
EMSG Conference 10 October 2007
AAIB Farnborough
Do your engineers sign off task cards sight unseen?
EMSG Conference 10 October 2007
AAIB Farnborough
Is the Approved Data correct and is there a viable
procedure to amend errors?
EMSG Conference 10 October 2007
AAIB Farnborough
MAINTENANCE ERROR AND BUSINESS RISK
EMSG Conference 10 October 2007
AAIB Farnborough
MAINTENANCE ERROR AND BUSINESS RISK
EMSG Conference 10 October 2007
AAIB Farnborough
MAINTENANCE ERROR AND BUSINESS RISK
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
EMSG Conference 10 October 2007
AAIB Farnborough
MAINTENANCE ERROR AND BUSINESS RISK
EMSG Conference 10 October 2007
AAIB Farnborough
MAINTENANCE ERROR AND BUSINESS RISK
…
EMSG Conference 10 October 2007
AAIB 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 2007
AAIB Farnborough
MAINTENANCE ERROR AND BUSINESS RISK
THE COSTS OF A MAINTENANCE EVENT
Rework/re-instatement costs
Additional hangar time costs
Repair costs for consequential damage
Maintenance re-scheduling and knock-on delays
Operational schedule related costs
Compensation costs
Cost of hiring a replacement aircraft
Business costs –
obtaining and retaining market share
EMSG Conference 10 October 2007
AAIB 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 2007
AAIB Farnborough
MAINTENANCE ERROR AND BUSINESS RISK
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
EMSG Conference 10 October 2007
AAIB Farnborough
MAINTENANCE ERROR AND BUSINESS RISK
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.
EMSG Conference 10 October 2007
AAIB Farnborough
THANK YOU FOR YOUR ATTENTION
EMSG Conference 10 October 2007
AAIB Farnborough