By David Millward, US Correspondent
The Telegraph
11 Mar 2014

Potential weakness in fuselage of Boeing 777s was identified by the Federal Aviation Administration last year

American transport officials warned of a potential weak spot in Boeing 777s which could lead to the “loss of structural integrity of the aircraft” four months before the disappearance of Malaysia airlines Flight MH370.

The Federal Aviation Administration in Washington drew up an Airworthiness Directive in November. It was triggered by reports of cracking in the fuselage skin underneath a Boeing aircraft’s satellite antennae.

In its directive the FAA, which is responsible for supervising the safety of American-made aircraft such as Boeing, told airlines to look out for corrosion under the fuselage skin.

This, the FAA said, could lead to a situation where the fuselage was compromised leading to possible rapid decompression as well as the plane breaking up.

“We received a report of cracking and corrosion in the fuselage skin underneath the SATCOM antenna adapter,” the FAA warned. “During a maintenance planning data inspection, one operator reported a 16-inch crack under the 3-bay SATCOM antenna adapter plate in the crown skin of the fuselage on an aeroplane that was 14 years old with approximately 14,000 total flight cycles.

“Subsequent to this crack finding, the same operator inspected 42 other aeroplanes that are between 6 and 16 years old and found some local corrosion, but no other cracking. Cracking and corrosion in the fuselage skin, if not corrected, could lead to rapid decompression and loss of structural integrity of the aeroplane.”

The FAA directive in November called for additional checks to be incorporated into the routine maintenance schedule of the worldwide 777 Boeing fleet.

According to a Malaysia Airlines spokesman, the missing aircraft was serviced on February 23, with further maintenance scheduled for June 19.

The FAA stated that carrying out necessary inspection work would cost airlines $3.060 (£1,841).

With terrorism now appearing less likely as a cause of the Malaysian airlines disaster, which claimed 239 lives, focus has switched to problems with the aircraft or pilot error.

Despite both the Boeing 777 and Malaysia Airlines having good safety records, there have been other incidents which could prove relevant during the investigation of the disappearance.

In 2005, a 777 operated by Malaysia Airlines suffered problems with its autopilot system on a flight between Perth and Kuala Lumpur.

It led to the plane pitching up into a sudden 3,000-foot climb, almost causing the plane to stall.

The problem led to another airworthiness directive to correct a computer fault that had been found on 500 Boeing 777s.

Airworthiness directives are commonplace, similar to car recalls.

In the majority of cases, airlines are told to look for and correct the fault, if found, during maintenance.

On rare occasions an entire fleet will be grounded as happened in January last year when the FAA ordered Boeing to stop flying its flagship 787 Dreamliner after faults were discovered with the plane’s batteries.

While investigators from Malaysia and the National Transportation Safety Board in Washington search for the plane’s black box, they will also be able to glean vital information from a live-data stream broadcast during the flight.

Known as Aircraft Communications Addressing and Reporting System, it is the equivalent of an “online black box”.

However James Healy-Pratt, an aviation lawyer who has represented bereaved families in other air accidents, warned they face a long wait before the original black boxes are recovered.

A Boeing spokesman said it was working with the NTSB as a technical adviser.

“The team is now in position in the region to offer whatever assistance is required.”

The company declined to comment further.