The US Federal Aviation Administration (FAA) had warned of a "cracking" problem on Boeing-777 airplanes, just days before the Malaysia Airlines flight MH370 went missing.
However, the FAA "airworthiness directive (AD)", dated March 5, only applied to Boeing 777-200, -200LR, -300, -300ER, and -777F series airplanes, and not the B777-200ER, which is the model of the missing Malysian Airline flight MH370.
The FAA cautioned against a link between the directive and the accident, and Laura Brown, the aviation regulator's deputy assistant administrator for public affairs, told Xinhua Wednesday "this applies only to US registered aircraft".
"The civil aviation authorities in other countries usually issue identical or similar directives that apply to aircraft registered in their countries," Brown added.
The FAA said the directive was prompted by a report of cracking in the fuselage skin underneath the satellite communication (SATCOM) antenna adapter.
"We are issuing this AD to detect and correct cracking and corrosion in the fuselage skin, which could lead to rapid decompression and loss of structural integrity of the airplane," the US aviation regulator said.
"This AD requires repetitive inspections of the visible fuselage skin and doubler if installed, for cracking, corrosion, and any indication of contact of a certain fastener to a bonding jumper, and repair if necessary," it said.
The directive, first drawn up Sep 26, 2013, was approved Feb 18 and published in the US Federal Register March 5. It is due to take effect April 9.
In the notice, the FAA said one operator had reported a 16-inch (40.6-cm)) crack under the three-bay SATCOM antenna adapter plate in the crown skin of the fuselage on an airplane that was 14 years old with approximately 14,000 total flight cycles.
It said following the crack finding, the same operator inspected 42 other airplanes between six and 16 years old and "found some local corrosion, but no other cracking".
The FAA said 120 airplanes of US registry are affected by the directive.
Meanwhile, search operations for the Beijing-bound Malaysian airliner that went missing Saturday continued for the sixth day Thursday.
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