MAINTENANCE ERROR
ACCIDENTS
By
Wg Cdr (Retd) M U Khan, VSM
Deputy General Manager (Flight Testing)
Hindustan Aeronautics Ltd
Maintenance Error Accidents
Maintenance is :
– Essential & Integral part of aviation
industry.
Thus
– Maintenance errors are likely to occur
just like the flight crew related errors.
Aim is to:
– Minimise the risk of maintenance
related accidents / incidents
Content
• Statistics of Indian Civil Helicopter
Accidents due to Maintenance reasons
• Contributory factors towards maintenance
errors
– Man
– Machine
– Environment
• New Safety Requirements
• Preventive and Predictive Maintenance
• Future Trends
Year Wise Statistics of Accidents (19902005)
8
7
No of Accidents
6
5
4
3
2
1
0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year
Total
Maintenance
Statistics of Accidents (1990-2005)
GROUND ACCIDENT
10%
MAINTENANCE
28%
OTHERS
5%
PILOT ERROR
57%
Breakdown of Maintenance Related
Accidents (1990-2005)
Technical Defects
60%
Improper Maintenance
40%
Fatal : 2
Substantial Damage : 8
Injury : 1
Total Loss
:3
Maintenance Issues
IMPROPER MAINTENANCE
•
Incorrect Attachment
•
Incorrect Connection
•
Omission
TECHNICAL DEFECTS
• Fatigue Failure
• Improper Manufacture
• Incorrect Assembly
•
Wrong part
• Internal Failures
•
Reversed Installation
•
Wrong Judgement
• Faulty Design
•
Improper tool/equipment
• Faulty Mfg Process
Maintenance Errors - Factors
MAN
MACHINE
ENVIRONMENT
Maintenance Errors
ERRORS
• Oversight
• Attention lapses
VIOLATIONS
• Non-compliance of laid
down instructions or
regulations
- Someone in most maintenance departments make
life or death decisions everyday.
- They determine if an aircraft is safe for flight or
not.
- Most component technical issues in helicopters
fall into shades of gray category
thus
• The maintenance personnel have a tough task to
perform to keep the fleet airborne.
• Their decision is easy if it’s a major safety of
flight issue – ‘The aircraft is down’.
• It is more difficult if it’s a minor discrepancy like
metal chips in a transmission, a leaky actuator or
minor cracks in secondary / tertiary structures.
• All military & commercial aircraft fly with minor
discrepancies.
THE INDIVIDUAL WHO MAKES SAFETY OF
FLIGHT DECISION CAN’T MAKE MISTAKES
However,
– Not all errors lead to incidents / accidents.
– Individuals usually realise their mistakes and
rectify them.
– Research has shown that people involved in
critical professions routinely make small
mistakes, which they detect and correct
themselves.
Other Human Factors
•
•
•
•
•
•
•
•
•
•
Lack of Communication
Complacency
Distraction
Lack of Knowledge
Lack of Teamwork
Fatigue
Lack of Assertiveness
Stress
Lack of Resources
Pressure
Environmental Aspects
• Mostly all maintenance activities take place by
night in artificial lighting conditions.
• Hangars & Tarmac may not be always available at
all times for maintenance operations.
• Heat, Dust, Rain etc can be source of initiation of
maintenance related incidents / accidents.
Errors due to the Machine
• The helicopter is a very complex machine as
compared to its fixed wing counterpart.
• It operates in adverse environment such as dusty
and salt laden atmosphere as well as close to
ground. Thus making it maintenance intensive.
• Present concept is to make the design for near
Zero routine maintenance for short terms and
‘inspect & replace’ for the longer term
maintenance cycles.
Avoid Maintenance Errors thru Design
• Design features known to be a source of human
errors are eliminated
• Software logic to prevent errors
• HUMS
(Health & Usage Monitoring system)
• IETMS
(Interactive Electronic Technical Manuals)
• Onboard Diagnostics
MODERN
HELICOPTER
ON-BOARD DIAGNOSTICS
Preventive Vs Predictive Maintenance
• Maintenance professionals emphasize prevention as an
inexpensive method of controlling maintenance costs
and ensuring safety.
• Technology has now advanced to such a point that a
new trend has emerged – Predictive Maintenance.
• But the two are not mutually exclusive.
• An operator who has adopted both approaches is
unlikely to get an unwelcome surprise from
maintenance problems.
• However the future is towards predictive maintenance.
Future Trends in Maintenance
• Onboard diagnostic systems to not only record but
also to analyse the data during the flight.
• Possibly relay the same to the maintenance agency
to ensure ‘just in time’ deliveries of replacement
parts rather than stockpiling them.
• Nanotechnology.
• Smart materials.
• Virtual Retinal Display.
Conclusion
• The human aspect of the maintenance personnel is
the most important area and needs careful
attention by both – the operator and the regulator.
• The environment plays a major role in ensuring
proper maintenance of our helicopters and thus
requires careful attention.
• Modern technologies can aid reduction in
maintenance error accidents.