Definition

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.

Description

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.

Further Reading

• 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
• Maintenance Briefing Notes: Maintenance Documentation by Airbus
• 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
• Operator's Manual: Human Factors in Aviation Maintenance, FAA, 2014
• Advisory Circular 120-115: Maintainer Fatigue Risk Management, FAA, 2016
• Paper 2009/05: Aircraft Maintenance Incident Analysis, UK CAA, 2009
• CAP 1367: Aircraft Maintenance Incident Analysis, UK CAA, 2016