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

0

1

2

3

4

5

6

7

8

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Year

No

of A

ccid

en

ts

Total Maintenance

Year Wise Statistics of Accidents (1990-2005)

Statistics of Accidents (1990-2005)

PILOT ERROR57%

MAINTENANCE28%

GROUND ACCIDENT10%

OTHERS5%

Breakdown of Maintenance Related Accidents (1990-2005)

Improper Maintenance

40%

Technical Defects

60%

Fatal : 2

Injury : 1

Substantial Damage : 8

Total Loss : 3

Maintenance Issues

IMPROPER MAINTENANCE

• Incorrect Attachment

• Incorrect Connection

• Omission

• Wrong part

• Reversed Installation

• Wrong Judgement

• Improper tool/equipment

TECHNICAL DEFECTS

• Fatigue Failure

• Improper Manufacture

• Incorrect Assembly

• Internal Failures

• Faulty Design

• 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

• H U M S (Health & Usage Monitoring system)

• I E T M S (Interactive Electronic Technical Manuals)

• Onboard Diagnostics

MODERN HELICOPTER MODERN HELICOPTER ONON--BOARD DIAGNOSTICSBOARD 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.