AAIB investigation to Boeing 737-4Q8, G-JMCR

Boeing 737- 4Q8 (G-JMCR), loss of electrical power, en route to East Midlands Airport, 12 October 2018.


The aircraft was operating a night flight to East Midlands Airport, with the left engine generator disconnected, and had just commenced its descent when the crew faced an unusual array of electrical failures on the flight deck. Despite the loss and degradation of a number of systems, the aircraft landed safely at East Midlands.

The electrical failures were caused by the right engine Generator Control Unit (GCU) which had been incorrectly secured in its mounting tray and had disconnected in flight. The investigation also uncovered a number of contributory factors including: the management of defects and Acceptable Deferred Defects (ADD), recording of maintenance, and a number of weaknesses in the operator’s Safety Management System with regards to managing risk.

Six Safety Recommendations are made to the operator regarding its safety management system and one to the Civil Aviation Authority.

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Boeing 737-4Q8, G-JMCR 10-19

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Glossary of abbreviations

Published 5 September 2019