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 (1990 2005)

8 7 6 5 2 1 4 3 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% OTHERS 5% PILOT ERROR 57% MAINTENANCE 28%

Breakdown of Maintenance Related Accidents (1990-2005)

Technical Defects 60% Improper Maintenance 40%

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

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.