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The unintended failure to carry out a maintenance task in accordance with the requirements of that task and/or not working in accordance with the principles of good maintenance practice.
Aviation industry studies have found that the origin of as many as 20% of all in-flight engine shutdowns can be traced to maintenance error.
Typical maintenance errors include:
- Electrical wiring discrepancies.
- Loose objects left in airplane.
- Incorrect installation of components.
- Fitting of wrong parts.
- Inadequate lubrication.
- Access panels, fairings, or cowlings not secured.
- Fuel or oil caps and fuel panels not secured.
For installation errors on engines, one specific study found the following types of error:
- Boroscope plug not refitted
- Engine Driven Pump (EDP) drive shaft seal not fitted
- Engine attachment bolts incorrectly fitted
- Anti Ice valves locked out
- Fire bottle squibs not fitted
- Fuel pipe not secured
- Magnetic Chip Detectors (MCDs) not fitted
- Prop spinner fitment not completed
- Fuel Control Unit (FCU) controls not fitted
The circumstances in which maintenance error occurs are the focus of human factors methodology.
- Analysis of maintenance error data collected by a group of UK Maintenance Organisations found that when the type of error was classified, four categories accounted for 78% of the errors. These were Installation error - 39%, Inattention (damage) - 16%, Poor inspection standards - 12% and Approved data not followed - 11%.
- The presentation of this data was accompanied by some solutions for both ‘people’ and ‘process’ for all the main types of error found. See: http://www.chirp-mems.co.uk/CHIRP-MEMS%20data%20review_files/frame.htm
- ATSB Transport Safety Report - AR-2008-055: An Overview of Human Factors in Aviation Maintenance, Alan Hobbs Ph.D.
- Airbus Maintenance Briefing Note Maintenance Error Management
- Human Factors in Aircraft Maintenance, Colin G. Drury, State University of New York
- Safety Behaviours: Human Factors Resource Guide for Engineers - Chapter 2: Error Management - CASA (Australia), 2013