Patee Sarasin, chief executive officer of Thailand regional airline Nok Air (Nok), has confirmed that none of the 737-400 series aircraft the airline operates are affected by an emergency safety directive issued by the US Federal Aviation Administration (FAA) for older Boeing 737 Classic series aircraft.
The FAA issued the inspection mandate yesterday, April 4, 2011, after unseen cracks expanded into a 0.5sq.m (5sq.ft) hole mid-flight late last week in the roof of a 737-300 operated by US carrier Southwest Airlines, causing it to make an emergency landing and seeing it suspend flight operations of all its 79 Boeing 737-300 aircraft.
The initial FAA order affects 175 of the 1,988 Boeing 737-300/-400/-500 series, termed the Boeing 7373 Classic Series, of short-to medium-range, narrow-body jet aircraft produced between 1981 and 2000, with 90 of the affected aircraft registered outside of the USA.
Built with a service life of about 20-years, the 737 is one of the world’s most flown aircraft, with an industry saying being that “it is estimated that a 737 is taking off or touching down somewhere in the world every five seconds”, with many aircraft still in service in excess of Boeing’s service life..
Mr. Patee said none of Nok’s 10 737-400 series aircraft, four of which are leased from national carrier Thai Airways International (THAI) and which have an average age of about 19 years, are affected by the FAA order, while the checking mandated (electromagnetic checking for microcracks), “is already part of our maintenance program, with or without the FAA directive”.
According to FAA Administrator Randy Babbitt, the initial mandate applies to Boeing 737 aircraft in the -300, -400 and -500 series that have accumulated more than 30,000 flight cycles.
The inspections are aimed to detect cracks in the planes‚Äô skin that can be caused by pressurization and depressurization of the cabin over tens of thousands of takeoffs and landings, but which are undetectable by visual inspection.
Mr. Babbitt said “these aircraft will need to be initially inspected using electromagnetic, or eddy-current, technology in specific parts of the aircraft fuselage, with repetitive inspections at regular intervals.”
Boeing said it was working closely with the National Transportation Safety Board (NTSB) and that: “Based on information from the NTSB investigation and Southwest’s inspections, Boeing is preparing a service bulletin that will recommend lap-joint inspections on certain 737-300/-400/-500 series airplanes”.
Mr. Patee said once the mandate from the FAA and/ or the Boeing service bulletin were received they would be examined, and if additional inspections are required they will be undertaken immediately.
Thai Airways 737-400s
With an average age of 12.1 years, about double that of regional air carrier giant Singapore Airlines, THAI operates one of the oldest fleets in the Southeast Asia region, with its four 737-400s having an average age of 15 years.
THAI said it “is waiting to be informed by the FAA via an AD notice if any of our aircraft required inspections. The FAA have details of all of our aircraft duty-cycles and if they are required to be inspected this will be undertaken immediately”, a THAI spokesperson not authorized to be quoted buy the media said. Neither Thai AirAsia or Bangkok Airways operate Boeing 737s.
In 2001 a 737-400 series aircraft operated by THAI exploded at (old) Bangkok Airport, totally destroying it and killing one crew member, moments before former prime minister Thaksin Shinawatra and 148 other passengers were due to board a flight to Chiang Mai.
At the time authorities blamed sabotage, but a later investigation showed the explosion and the resulting total destruction of the aircraft, valued than at Bt2.157 billion (about $US71,263 at current exchange rates), was the result of fuel vapors in an empty fuel cell exploding.
One of the most dramatic examples of a fuselage failure of a Boeing 737 occurred in Hawaii in 1988, when Aloha Airlines Flight AQ 243, a 737-200 aircraft with a duty cycle of 89,090 takeoffs and landings, suffered extensive damage after a mid-flight explosive decompression tore the entire top half of the aircraft fuselage off at the front of the aircraft, injuring 65 passengers and killing one flight attendant.
Up until January 2010 Boeing 737 Classic series 737-300/ -400/ -500 series aircraft have been involved in 266 “hull-loss” incidents resulting in 1,050 fatalities.
¬© John Le Fevre, 2011
Chiang Mai ‚Ä¢ Thailand current events ‚Ä¢ Thailand tourism ‚Ä¢ Thailand travel ‚Ä¢ Thaksin Shinawatra ‚Ä¢ Nok Air ‚Ä¢ Patee Sarasin¬†¬†¬† ‚Ä¢ Aloha Air Flight 243 ‚Ä¢ Boeing Classic Series ‚Ä¢ Boeing 737 ‚Ä¢ FAA air safety
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