AMERICA’S AVIATION AUTHORITY has demanded that all airlines using a certain older model of Boeing jet conduct immediate tests for “fatigue damage” after a five-foot hole emerged in the fuselage of one such plane during a flight last week.

All Boeing 737 jets from the -300, -400 and -500 series having accrued more than 30,000 flight cycles will be required to undergo initial inspections “using electomagnetic, or eddy-current, technology in specific areas of the aircraft”, according to an order of the Federal Aviation Administration taking effect today.

The investigations follow an in-flight emergency when a hole measuring five-foot long and one foot wide emerged in the roof of a 737-300 operated by Southwest Airlines during an internal flight last Friday.

An ongoing investigation into Southwest’s fleet in the wake of that incident – which thankfully did not cause injury – saw the airline reveal that three other 737-300 jets had developed sub-surface cracks.

The New York Times suggests that the investigations into Friday’s events – the third incident so-called ‘metal fatigue’ in as many years – had focussed on the airline’s intensive flight schedules, which can see its planes complete up to 12 flight segments a day.

“Safety is our number one priority,” the US’s transportation secretary Ray LaHood said. “Last Friday’s incident was very serious and could result in additional action depending on the outcome of the investigation.”

The announcement will apply to 175 planes worldwide, 80 of which are in the United States.

The announcement does not affect either Ryanair of Aer Lingus; the former’s fleet is comprised exclusively of Boeing 737-800s, which entered service in 1998, while the latter’s current fleet is manufactured entirely by Airbus.

In Aer Lingus’s case, any planes that might have been subject to the mandatory inspections were retired by 2005 at the latest.