In May, just two months before a Southwest plane developed a hole in its fuselage during flight, the Federal Aviation Administration issued new regulations that required far more detailed inspections of Boeing 737 fuselages "for any chafing or crack in the fuselage skin."
The directive applied to the tail-fin area of the plane, just a few feet from where the football-sized hole developed on Monday during Southwest Flight 2294 from Nashville, Tenn., to Baltimore. The Boeing 737-300 was carrying 131 people and made an emergency landing in West Virginia with no injuries.
Federal investigators are now scouring the plane's maintenance records for a clue as to what caused the fuselage skin to peel away.
The plane, which went into service in 1994, had undergone regularly scheduled maintenance and inspections, and no problems were found, Southwest Airlines said Thursday. In addition, notes Southwest spokeswoman Marilee McInnis, "Boeing and the FAA have confirmed there are no regulations or service bulletins that call for skin inspections in that area."
But the new FAA inspection regulation issued in May, called an airworthiness directive (AD), does affect an area not far away from where the hole in the Southwest plane developed. The AD was issued as a result of an "18-inch crack found in the fuselage skin area under the blade seals of the nose cap of the dorsal fin" in another Boeing 737 in 2004.
The May AD required much more detailed inspections of the fuselage around the tail-fin area. The FAA estimated that the old inspection methods would take only two hours, while the new, more detailed inspection was estimated to take 15 hours. The inspections are supposed to be done after every 9,000 cycles (one cycle is each time a plane takes off and lands).
It's unclear whether the Southwest plane that developed the hole had undergone the new inspection procedure. The National Transportation Safety Board has impounded the plane's maintenance records as part of its investigation.
At this point, the FAA says, there appears to be no direct connection between the AD and Monday's incident, but there could be an indirect one.
"One possibility is that in doing the work that was required by that AD, mechanics may have had to walk on the area where the incident occurred. But we just don't know because the investigation is at such an early stage," says Les Dorr, an FAA spokesman. "But there's nothing to suggest at this point the two are directly connected."
In March, Southwest paid the FAA a $7.5 million fine, the second largest in FAA history, for flying 46 Boeing 737s without performing mandatory inspections for fuselage cracks in 2007.
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