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Maintenance Error

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Article Information
Category: Human Behaviour Human Behaviour
Content source: SKYbrary About SKYbrary
Content control: SKYbrary About SKYbrary


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.

Further Reading