Maintenance-Related Accidents

Maintenance errors contribute to a significant share of accidents, though they rarely act alone. The typical pattern is an error made days, months or even years before the accident flight: a wrong part fitted, a panel or cap left unsecured, an inspection skipped or signed off without being done, a procedure changed to save time.

The error then waits, hidden, until the conditions for an accident come together. Investigations look at the organisation as much as at the individual: shift handovers, time pressure, instructions that were unclear or impractical, poor lighting, and fatigue among technicians working through the night. The human factors programmes now required of maintenance organisations, the human factors training of EASA Part-145 and Part-66, and the list of common error causes known as the Dirty Dozen all grew from accidents like these. For flight crews, the lesson is that a careful walk-round and an attentive reading of the technical log are the last defences against an error made by someone else, somewhere else. The reports below trace how each error reached the flight.

The investigations

AAIASB · 2005

Helios Airways Flight 522

14 August 2005 · Boeing 737-31S (737-300)

A 737 left Larnaca with its pressurisation in manual; the crew mistook the cabin altitude horn, lost consciousness from hypoxia, and the aircraft flew on autopilot until its fuel ran out.

PressurisationIncapacitationMaintenanceCRMHuman factors

GPIAA · 2001

Air Transat Flight 236

24 August 2001 · Airbus A330-243

A fuel leak from a mis-installed engine tube, crossfed instead of isolated, left an A330 without fuel over the Atlantic; the crew glided it to a landing in the Azores.

FuelMaintenanceHuman factorsEngine failure

NTSB · 2000

Alaska Airlines Flight 261

31 January 2000 · McDonnell Douglas MD-83

An MD-83's stabiliser trim jackscrew lost its nut threads through lack of grease, and extended check intervals let the wear go undetected until pitch control was lost.

MaintenanceFlight controlsLoss of control

NTSB · 1989

United Airlines Flight 232

19 July 1989 · McDonnell Douglas DC-10-10

A DC-10's tail engine fan disk burst in cruise and cut all three hydraulic systems; the crew steered it to Sioux City using engine thrust alone.

Engine failureFlight controlsMaintenanceCRMSurvival

Crash Investigations pages summarise official investigation reports for study and exam preparation. The investigating body's report is the authoritative account and prevails wherever it differs from this page. Under ICAO Annex 13, an investigation exists to prevent accidents, not to apportion blame or liability.