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.
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.