New Details on Southwest 1380

There are new details emerging about the deadly Southwest Airlines engine failure yesterday. The NTSB reports that a fan blade on the engine was missing and there are striking parallels between yesterday's accident and a 2016 incident on another Southwest 737.

The 737-700 uses CFM 56-7B engines manufactured by CFM International, a joint venture between GE and Safran Aircraft Engines. The original CFM 56 first ran in 1974 and has been continuously updated since then. The -7 version of the engine dates back to 1995 and is used on a large number of 737 variants. The shutdown rate of the CFM 56 is reported to be only only one for every 333,333 hours and the engines log an average of one million flight hours every eight days.

The CFM 56 is classified as high bypass turbofan, meaning that most of the air that passes through the engine flows around the sides through bypass ducts rather than through the engine's combustion section. The engine's fan is the large rotating set of blades that can be seen at the engine inlet. Behind the fan is a series of compressors, turbines and igniters that first compress the intake air, mix it with jet fuel and then it burn it under high pressure to create thrust.

The CFM 56 has had a history of fan blade problems, although most of the incidents occurred with older versions of the engine. In 1989, a 737-400 fitted with CFM 56-3C engines suffered a fan blade failure. The pilots of the British Midlands jet shut down the wrong engine and the damaged engine subsequently quit completely. The resulting crash killed 47 people and injured 74 in what became known as the Kegworth air disaster. Two other 737-400s fitted with the same engines experienced fan blade problems shortly after, resulting in a fleet wide grounding of all 737-400s while fans were replaced and engine controls were modified to reduce the engine's maximum thrust.

The -7 version of the engine experienced a comparable problem in 2016 when Southwest Flight 3472 experienced a fan blade separation very similar to yesterday's incident. On the flight from New Orleans to Orlando, the 737-700 suffered a fan blade failure that also caused engine parts to puncture the cabin pressure vessel and led to a depressurization. There were no serious injuries and the incident led to a requirement to inspect fan blades for corrosion and cracks caused by metal fatigue.

CNN reports today that NTSB Chairman Robert Sumwalt said that one of the accident aircraft engine's 24 fan blades was missing and that there was evidence of metal fatigue where the blade attached to the spinner hub.

Sumwalt cautioned against drawing conclusions based on the earlier Southwest incident. “We want to look at this particular event and see what the factors are surrounding this and maybe they’re related and maybe not,” he told Flight Global. “We need to understand what’s going on here.”

Southwest CEO Gary Kelly said after the incident that the engine had been inspected on April 15 and returned to service. It is not clear if the recent inspection included checks for metal fatigue or focused on the fan blades.

Although it is still early in the investigation, it seems that fan blade separation due to metal fatigue is the likely cause of the accident. If this is confirmed, the NTSB and FAA may issue an inspection directive similar to 2016. With the CFM 56-7B powering some 13,400 airliners worldwide, inspections could be an expensive proposition in terms of both compliance and scheduling. In addition to Southwest, the 737-700 is operated in the US by several other carriers including Delta, United and Alaska Airlines.

When asked about the parallels between Southwest 3472 and whether the NTSB would recommend a fix or inspection for fatigue in the fan section, Sumwalt answered, “I don’t have that information right now. Our focus is getting out the door at headquarters and getting on this airplane so we can get up to Philadelphia.”

Originally published on The Resurgent

Southwest Engine Failure Kills Passenger

A Southwest Airlines flight from New York's LaGuardia airport to Dallas suffered a catastrophic engine failure yesterday that left one woman dead. The fatality was the first US airline death in nine years.

Southwest 1380 was a Boeing 737-700 twin-engine airliner operated by the Dallas-based, low fare airline. The flight is typically scheduled to take just under four hours. The aircraft left the gate at LaGuardia at 10:27 a.m., three minutes early, and took off 16 minutes later.

As the airplane climbed to its planned cruising altitude of 38,000 feet, it suffered what appears to be an uncontained failure of the left engine. Radar data from FlightAware.com shows that the plane only attained an altitude of about 32,000 feet before it started its descent. By this point, the plane was northwest of Philadelphia and about 20 minutes into the flight.

Generally, when pilots say they “lost an engine” they mean they lost power on the engine. In this case, it looks as though the Southwest crew lost large pieces of their engine. Pictures of the engine show the cowling at the front the engine nacelle peeled back or missing with much of engine's interior exposed.

On the portion of the air-traffic audio that has been released, a Southwest pilot tells the controller, “We have a part of the aircraft missing, so we're going to need to slow down a bit.” This indicates that the crew suspected structural damage after the engine explosion and didn't want to stress the airplane with high speed flight.

Jet engines contain a number of fans and turbines that spin at a high rate inside the engine cowling. In the case of Southwest 1380, it appears that finely-machined guts of the jet engine came apart violently, turning fan blades and other engine parts into shrapnel that peppered the fuselage. One of the pieces of engine hit a cabin window, causing a small hole and injuring a female passenger. A passenger reported that the crew was trying to plug the hole when the window completely shattered, pulling the female passenger partly outside the plane.

The woman's head and arms were outside the window and “passengers right next to her were holding onto her. And meanwhile, there was blood all over this man's hands. He was tending to her,” passenger Marty Martinez told CNN.

Airline cabins are pressurized by excess air from the engines. Contrary to popular belief, it takes a large hole to affect the cabin pressure. There are even holes built into the fuselage called outflow valves that allow excess cabin air to be dumped overboard to prevent overpressurization. In the case of window breaking, the engine air cannot keep up with the pressurization demands of the cabin and the airplane experiences a rapid decompression.

In a rapid decompression, the air inside the airplane rushes out quickly with a loud noise and the temperature quickly drops to below freezing. Wind and engine noise through the open window add to the chaos.

A rapid decompression is a maneuver that jet pilots routinely train for in the simulator. The pilots first don their oxygen masks since the thin air at high altitudes will render a person unconscious in a matter of seconds. The next step is to put the airplane into a steep dive to a safe lower altitude while making sure that the passenger oxygen masks have deployed in the cabin.

This steep, controlled dive may have given some passengers the incorrect idea that the airplane was descending out of control. FlightAware shows that the airplane descended from 30,000 to 10,000 feet, which is considered a safe altitude for an unpressurized aircraft, in about five minutes as it turned toward Philadelphia.

As the crew approached the airport, the pilot said, “Could you have the medical meet us there on the runway as well? We've got injured passengers.” She said that airplane was not on fire, but repeated, “Part of it's missing.”

“They said there's a hole and someone went out,” she added.

The plane landed uneventfully in Philadelphia about 20 minutes after the engine failure. One passenger was killed, but there were no other serious injuries reported among the 143 passengers and 5 crew members. Seven passengers reported minor injuries. The entire flight lasted only 40 minutes.

The only fatality was Jennifer Riordan, of Albuquerque, N.M., the New York Daily News reported. Riordan, vice president of community relations at Wells Fargo, is assumed to be the female passenger who was pulled partially out of the window, but this has not been confirmed.

US airline accidents have become exceedingly rare. The last fatal accident was in 2009 when the crash of Colgan 3407 left 49 passengers and crew dead as well as one person on the ground.

There have been similar accidents in US history where the endings were more tragic than Southwest 1380. In 1989, an engine exploded on a United Airlines DC-10, severing the flight controls and leaving the crew airborne with no way to control the airplane. Using the throttles for the remaining engines, the crew of United 232 was able to steer the plane to a crash landing in Sioux City, Iowa that left 111 of the 296 passengers and crew dead.

A year earlier in 1988, Aloha Airlines Flight 243 suffered a rapid decompression when a section of the cabin ceiling peeled off the aircraft at 23,000 feet. A flight attendant was sucked out of the 737-200 over the Pacific Ocean near Maui and her body was never recovered. The crew safely landed the airplane with no further deaths.

Southwest CEO Gary Kelly said that the engine had been inspected on April 15 and had flown about 40,000 cycles. It had been about 10,000 cycles since the engine's last overhaul.

“I'm not aware of any issues with the airplane or any issues with the engine involved,” Kelly said.

The cause of the catastrophic engine failure is not known. While extremely reliable, jet engines are not infallible. National Transportation Safety Board Chairman Robert Sumwalt said that board sees “about three or four [uncontained failures] a year, but not all involve US airlines. With airlines flying about 17 million hours annually, three or four failures is about as close to error-free as any transportation system can get.

In fact, aviation machines are so reliable that the weak link often lies with pilots and maintenance personnel. Southwest has been fined several times by the FAA for maintenance violations, but this is not unusual in itself. Many of the violations are technical and other airlines such as United and Delta have also been fined by the FAA.

In modern times, our machines are so reliable that we forget that flying five miles above in the earth in a pressurized metal tube that hurtles along 500 miles per hour is inherently dangerous. Things can and do go wrong, sometimes for no apparent reason and with no one to blame. It is at that time that the pilots truly earn their pay. The pilots of Southwest 1380 certainly earned theirs.

Originally published on The Resurgent

Jenni Rivera killed in Mexican Lear crash

The National Transportation Safety Board has confirmed in a press release today that Mexican-American singer Jenni Rivera has died in a plane crash in Mexico. The NTSB is assisting Mexican civil aviation authorities in the investigation.

According to preliminary details published on Aviation-Safety.net, the crash occurred on December 9 at approximately 4:00 a.m. local time. The crash occurred shortly after takeoff from Monterrey, Mexico (MMMY). The aircraft was enroute to Toluca airport (MMTO) near Mexico City. The crash site is reportedly near the town of Iturbide, Mexico which is located approximately 100 miles south of Monterrey.

Weather reports from the time of the crash available on aviationweather.gov indicated visibility as low as one eighth of a mile in fog and mist. The fact that Monterrey is surrounded by high terrain coupled with the low visibility at the time of the accident point to controlled flight into terrain as a possible cause of the accident.

The accident aircraft was N345MC, a 1969 Lear 25 private jet. The aircraft was registered Starwood Management of Las Vegas according to FlightAware.com. Although the aircraft has a capacity of eight passengers and two crewmembers, only five passengers were aboard the accident flight. All five passengers and both crewmembers were reportedly killed in the accident. The aircraft was totally destroyed.

Aviation-Safety.net’s accident database lists a total of 55 Lear 25 accidents dating back to 1969 when the aircraft was first produced. Forty of the accidents resulted in fatalities. Production of the model ended in 1984 with 373 airplanes.

Originally published on Examiner.com:
http://www.examiner.com/article/ntsb-confirms-jenni-rivera-killed-mexican-plane-crash?cid=db_articles