National Grid failures led to fire that caused Heathrow shutdown, report says

STORY: A fire that shut Heathrow Airport in March, stranding thousands of passengers, was caused by National Grid's failure to maintain an electricity substation.

That's according to an official report released Wednesday.

The closure of Heathrow, the busiest airport in Europe, cost airlines tens of millions of pounds.

It also raised questions about the resilience of Britain's infrastructure.

The report follows a review of the incident on March 21 by the National Energy System Operator.

It manages the electricity network and was separated from National Grid last year.

As a result of the report, Britain's energy regulator Ofgem launched an enforcement investigation.

It said its review had seen evidence that a “catastrophic failure” on one of the transformer’s high voltage bushings at the substation caused the transformer to catch fire.

And that National Grid controls in place were not effective.

A National Grid spokesperson said that the company had a comprehensive asset inspection and maintenance programme in place.

And that it had taken further action since the fire.

Ofgem plans to review whether National Grid had complied with the relevant legislation and licence conditions.

As well as an independent audit to review whether the failings were a one-off or systemic.