2018 aviation accident over Pennsylvania, U.S.
Southwest Airlines Flight 1380 was a Boeing 737-700 that experienced a contained engine failure in the left CFM International CFM56 engine after departing from New York–LaGuardia Airport en route to Dallas Love Field on April 17, 2018. The engine cowl was broken in the failure, and cowl fragments damaged the fuselage, shattering a cabin window and causing explosive depressurization of the aircraft. Other fragments caused damage to the wing. The crew carried out an emergency descent and diverted to Philadelphia International Airport. One passenger was partially ejected from the aircraft and sustained fatal injuries, while eight other passengers sustained minor injuries. The aircraft was substantially damaged and written off as a result of the accident.
This accident was very similar to an accident suffered 20 months earlier by Southwest Airlines Flight 3472 flying the same aircraft type with the same engine type. After that earlier accident, the engine manufacturer, CFM, issued a service directive calling for ultrasonic inspections of the turbine fan blades with certain serial numbers, service cycles, or service time. Southwest did not perform the inspection on the engine involved in this failure because it was not within the parameters specified by the directive.
Background.
The aircraft involved was a Boeing 737-7H4 with manufacturer's serial number 27880, fuselage line number 601, and registered as N772SW. The aircraft had been in service with Southwest Airlines for nearly 18 years since its manufacture in 2000. It was powered by two CFM International CFM56-7B24 engines.
Five crew members and 144 passengers were on board.
Tammie Jo Shults, aged 56, a former United States Navy fighter pilot, was the captain of the flight. She had been with Southwest Airlines since 1994 and had logged a total of 11,715 flight hours, including 10,513 hours on the Boeing 737.
Darren Lee Ellisor, aged 44, a former United States Air Force (1997–2007) pilot with experience in the Boeing E-3 Sentry and a veteran of the Iraq War, was the first officer. He had been with the airline since 2008 and had 9,508 flight hours, with 6,927 hours on the Boeing 737.
Accident.
At 11:03am Eastern Daylight Time, the aircraft was flying at and climbing when the left engine failed. As a result, most of the engine inlet and parts of the cowling broke off. Fragments from the inlet and cowling struck the wing and fuselage and broke a window at row 14 in the passenger compartment, which caused an uncontrolled decompression of the aircraft. The flight crew carried out an emergency descent of the aircraft and diverted it to Philadelphia International Airport (PHL).
The flight crew stated that the departure and climb from LaGuardia were normal, with no indications of any problems; First Officer Ellisor was the pilot flying at the time of the engine failure, and Captain Shults was monitoring. They reported that the aircraft yawed, several cockpit alarms went off, a "gray puff of smoke" appeared, and the aircraft's cabin suddenly lost air pressure. The flight crew donned their emergency oxygen masks, and the first officer began the emergency descent. The flight data recorder (FDR) showed that the left engine's performance parameters all dropped simultaneously, vibration became severe, and within five seconds, the cabin altitude alert activated. The FDR also showed that the aircraft rolled left by about 40° before the flight crew was able to counter the roll. The flight crew reported that the aircraft was very difficult to control throughout the remainder of the flight because of the extensive damage. The captain took over flying the plane, and the first officer carried out the emergency checklist. The captain asked the air traffic controller for a course diversion. She initially requested a course to the nearest airport but then decided that PHL was best equipped for this aircraft's emergency. The controller quickly provided vectors to PHL. The flight crew reported initial communications difficulties because of the loud noises, distraction and wearing oxygen masks, but as the aircraft descended, communications improved. The captain initially planned on a long final approach to make sure the crew completed all the emergency checklists. Upon learning of the passengers' injuries, however, she decided to speed the approach and expedite landing.
Three flight attendants, Rachel Fernheimer, Seanique Mallory, and Kathryn Sandoval, were assigned to the flight, and another Southwest Airlines employee was onboard as a passenger. All four reported that they heard a loud sound and felt severe vibration. The oxygen masks automatically deployed in the cabin. The flight attendants retrieved portable oxygen bottles and began moving through the cabin to assist passengers with their oxygen masks. As they moved toward the mid-cabin, they found an adult female passenger in row 14 partially blown out the broken window. With the help of two passengers, flight attendants pulled the victim inside the aircraft and other passengers performed CPR. The passenger died after being admitted to a local hospital for treatment. A spokesperson for the Philadelphia Department of Public Health stated the cause of death of the passenger was blunt force trauma to the head, neck and torso. Eight other passengers sustained minor injuries.
The aircraft was substantially damaged and written off as a result of the accident.
Investigation.
Initial investigation.
The participants in the investigation included the National Transportation Safety Board (NTSB), the United States Federal Aviation Administration (FAA), Boeing, Southwest Airlines, GE Aviation, the Aircraft Mechanics Fraternal Association, the Southwest Airlines Pilots' Association, the Transport Workers Union of America and UTC Aerospace Systems. Because the manufacturer of the failed engine (CFM) is a US-French joint venture, the French Bureau of Enquiry and Analysis for Civil Aviation Safety also contributed investigators. Technical teams from CFM assisted with the investigation. The NTSB expected the investigation to take 12 to 15 months.
NTSB investigators analyzed a recording of the air traffic radar plots and observed that the radar had shown debris falling from the aircraft and used wind data to predict where ground searchers could find it. Parts from the engine's nacelle were found in the predicted area at several locations near the town of Bernville in Berks County, Pennsylvania, northwest of Philadelphia.
On April 20, 2018, CFM issued Service Bulletin 72-1033, applicable to the CFM56-7B-series engine, and on the same day, the FAA issued emergency airworthiness directive (EAD) 2018-09-51 based on it. The CFM service bulletin recommended ultrasonic inspections of all fan blades on engines that had accumulated 20,000 engine cycles and subsequently at intervals not to exceed 3,000 engine cycles. The EAD required CFM56-7B engine fleet fan blade inspections for engines with 30,000 or greater cycles within 20 days of issuance, per the instructions provided in the service bulletin and if any crack indications were found, the affected fan blade was required to be removed from service before further flight. This directive was issued as a one-time inspection requirement. On the same day, European Aviation Safety Agency also issued EAD 2018-0093E (superseding EASA AD 2018-0071) that required the same ultrasonic fan blade inspections to be performed. The engine manufacturer estimated the new directive affected 352 engines in the US and 681 engines worldwide.
On April 23, 2018, Southwest Airlines announced that it was voluntarily going beyond the FAA EAD requirement and performing ultrasonic inspections on all CFM engines in its fleet, including two each on around 700 Boeing 737-700 and 737-800 aircraft.
On April 30, 2018, the aircraft involved in the accident was released by the NTSB and was flown by Southwest Airlines to a service facility performing major services on Boeing aircraft at Paine Field in Everett, Washington, for repairs.
On May 2, 2018, the FAA issued follow-up airworthiness directive (AD) 2018-09-10, which expanded the inspections on CFM56-7B engines beyond the original EAD 2018-09-51. The new AD required inspections of engines with lower cycles and introduced repeat inspection requirements, including a requirement to perform detailed inspections on each fan blade before it accumulated 20,000 cycles since new or within 113 days, whichever occurred later, or within 113 days from the effective date of the AD if cycles since new on a fan blade were unknown with repeat inspections no later than 3,000 cycles since the last inspection. If any unserviceable fan blade was found, it was required to be removed from service before further flight. The FAA estimated that this AD affected 3,716 engines installed on aircraft of U.S. registry at an estimated cost of US$8,585 per blade replacement.
After flying to Paine Field in Everett, the plane then moved to Southern California Logistics Airport in Victorville, California on June 7, 2018, where it was placed into storage. The aircraft remained there and never flew again. It had its Southwest titles removed, but remained in the basic Southwest livery. The aircraft was scrapped in 2022.
Preliminary findings.
On May 3, 2018, the NTSB released an investigative update with preliminary findings:
NTSB investigative hearings.
The NTSB held an investigative hearing on November 14, 2018. At the hearing, FAA Transport Standards Branch representative Victor Wicklund stated that the production inlets were not required to be subjected to certification testing, but if they were included and test damage mirrored that of the accident aircraft, it would most likely constitute a certification failure. He indicated that the cowling may require design changes.
The NTSB held a second investigative hearing on November 19, 2019. The NTSB also issued five safety recommendations to the FAA, one to EASA and one to Southwest.
Final report.
On November 19, 2019, during the second hearing, the NTSB released the final report on the accident. The probable cause reads:
The National Transportation Safety Board (NTSB) determines that the probable cause of this accident was a low-cycle fatigue crack in the dovetail of fan blade No. 13, which resulted in the fan blade separating in flight and impacting the engine fan case at a location that was critical to the structural integrity and performance of the fan cowl structure. This impact led to the in-flight separation of fan cowl components, including the inboard fan cowl aft latch keeper, which struck the fuselage near a cabin window and caused the window to depart from the airplane, the cabin to rapidly depressurize and the passenger fatality.
The major recommendation of the report was that the Federal Aviation Administration should require Boeing to discover, for this aircraft and engine type, which parts of the engine fan case were susceptible to transmitting damage to the fan cowl structure and then redesign the fan cowl so that it retains its integrity after such a "blade out" event.91
Nacelle inlet and cowl redesign.
The FAA required Boeing to redesign in compliance with applicable Part 25 regulations. A proposed rule receives comments until January 26, 2024. Approval of the rule will require airlines to make the relevant modifications by July 31, 2028.
Reactions.
On the day of the incident, Elaine Chao, the United States Secretary of Transportation, made a statement to "commend the pilots who safely landed the aircraft and the crew and fellow passengers who provided support and care for the injured, preventing what could have been far worse." Shortly thereafter, Martha McSally, then a member of the United States House of Representatives from Arizona, introduced a resolution in Congress commending Captain Shults.
On May 1, 2018, U.S. President Donald Trump welcomed crew members and select passengers in a ceremony at the Oval Office of the White House, thanking them all for their heroism.
Southwest Airlines gave each passenger $5,000 and a $1,000 voucher for future travel with the airline. Southwest Airlines bookings fell following the accident, resulting in a projected decline in revenue for the airline for the second quarter of 2018. Following the accident, passenger Lilia Chavez filed a lawsuit against Southwest Airlines claiming that she suffers from post-traumatic stress disorder since the accident. Her lawsuit was later settled.
Captain Shults wrote a book about the incident titled "Nerves of Steel". The book was published in the United States on October 8, 2019.
In popular culture.
The incident involving Flight 1380 was featured on the fifth episode of season 21 of the Canadian documentary series "Mayday", known in the United States as "Air Disasters". The episode is titled "Cabin Catastrophe".
References.
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