737-300S GROUNDED IN USA AS INSPECTIONS TAKE PLACE. THE AGE FACTOR IS THE GROWING STORY OF 2011 BUT IS THIS YET ANOTHER CHAPTER OR A LAPSE?

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By TESTCustomwebLP TESTCustomwebLP April 4, 2011 18:57

737-300S GROUNDED IN USA AS INSPECTIONS TAKE PLACE. THE AGE FACTOR IS THE GROWING STORY OF 2011 BUT IS THIS YET ANOTHER CHAPTER OR A LAPSE?

We always worry when there is a rush of similar mishaps with aircraft and we are at this time witnessing far too many occurrences of metal fatigue failures in many aircraft types including the older 737 types and 757 aircraft. All of this confirms the fact that aircraft age ranges and regulation of the same is the biggest story in aviation as we move through 2011.

The US market in particular is heavily affected and it may be that airlines have no alternative but to turn to the lessors.

Southwest Airlines cancelled 300 flights yesterday (Sunday) as it began inspecting 79 of its Boeing 737-300s…

The grounding of Southwest 737-300s follows an emergency on Friday when a flight from Phoenix to Sacramento had to make an emergency landing at the Marine Corps Air Station in Yuma, Arizona. Flight 812 had reached an altitude of 34,500 feet when a five foot section of the overhead fuselage ripped open, depressurizing the cabin and slightly injuring a flight attendant and one passenger. A lucky escape.

As grounded aircraft go into the hangers, inspectors will be looking for evidence of aircraft skin fatigue. On the aircraft that developed the fault, flight data recordings and maintenance records will be inspected too. Of the latter, FAA records show cracks were found and repaired a year ago in the frame of the Southwest Airlines Boeing 737-300 that made an emergency landing at an Arizona military base after a hole was torn from the passenger cabin.

Yesterday, federal investigators examining the damaged plane in Yuma said the entire length of a five-foot-long tear in the skin of the aircraft shows evidence of pre-existing fatigue cracking.

National Transportation Safety Board member Robert Sumwalt said that the rip was a foot wide, and that it started along a lap joint where two sections of the 737′s skin are riveted together. “We did find evidence of widespread cracking along this entire fracture surface,” Sumwalt said. He also noted that the extensive multi-site damage could have been spotted during routine maintenance. “We have no indication that something was missed in an inspection that should have been caught.” He told reporters.

Federal Aviation Administration records of maintenance for the aircraft showed that a March 2010 inspection found 10 instances of cracking in the aircraft frame, which is part of the fuselage, and another 11 instances of cracked stringer clips, which help hold the plane’s skin on. The records show the cracking was either repaired or the damaged parts replaced.

The cracking accounted for a majority of the 28 problem reports filed as a result of that inspection.

Three more Southwest Airlines planes have been found with similar small, subsurface cracks. Southwest said in a statement yesterday that it had found cracks in two Boeing 737-300s but a National Transportation Safety Board (NTSB) member later said a third plane was discovered to have the cracks as well.

The US fleet includes 288 Boeing 737-300s (about 170 of them flown by Southwest), and 931 operate worldwide.

According to Southwest, the airline over the years has replaced the skin on most of its 737-300s, which is the oldest aircraft in Southwest’s fleet. Those grounded for inspection this weekend had not yet had their skin replaced.

You may recall that in July, 2009, Southwest Flight 2294 flying from Nashville to Baltimore at 34,000 feet had a football-sized hole in its fuselage near the tail, which caused rapid decompression and a forced landing in Charleston, West Virginia. No one was injured. The NTSB determined that metal fatigue had been the cause.

Keep an eye on this story and the effect it has. We will be looking at the aircraft age range regulations and their impact in the next issue of Airline Economics out soon.

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By TESTCustomwebLP TESTCustomwebLP April 4, 2011 18:57
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