Southwest Airlines Flight 1380

Southwest Airlines Flight 1380 was a regularly scheduled passenger flight operating from LaGuardia Airport in New York City to Dallas love Field in Dallas, Texas. On April 17, 2018, 12 minutes after departure from LaGuardia, the Boeing 737-7H4 was climbing through 32,000 feet (9,800 m) when the aircraft's number one CFM56-7B engine suffered a contained engine failure. Fragments from the engine inlet and cowling struck the wing and fuselage, resulting in a rapid depressurization after the loss of one passenger window. The flight crew conducted an emergency descent and diverted to Philadelphia International Airport in Philadelphia, Pennsylvania. Of the 144 passengers and five crew members onboard, one passenger received fatal injuries and eight passengers received minor injuries. The airplane sustained substantial damage.

This accident was identical to the accident suffered 20 months earlier by Southwest Airlines Flight 3472 involving the same type of aircraft and engine. After that 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 do this as this engine was not within the parameters specified by the directive.

This was the first fatal airline accident involving a U.S. passenger carrier since the crash of Colgan Air Flight 3407 in February 2009, and the first aircraft accident involving Southwest Airlines that resulted in the death of a passenger.

Aircraft
The aircraft operating Flight 1380 was a Boeing 737-7H4, serial number 27880, registered N772SW, first flown on 26 June 2000 and delivered new to Southwest Airlines in the same year. The airframe had accumulated 63043 hours of flight time and 36728 cycles (takeoffs and landings) at the time of the accident. The aircraft was powered by two CFM56-7B engines.

After the accident the aircraft was subsequently flown to Boeing in Everett, on April 30, 2018 for repairs. The plane was moved into storage at Victorville on June 7, 2018. The aircraft remains there and has not made a scheduled revenue flight since.

Crew
The captain of Flight 1380 was 56-year-old Tammie Jo Shults, a former United States Navy pilot who served from 1985 to 1993. Captain Shults first joined Southwest Airlines in 1994 and had logged a total of 11,715 flight hours, including 10,513 hours on the Boeing 737. The first officer of the flight was 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 in the Iraq War. He had been with the airline since 2008 and had 9,508 flight hours, with 6,927 of them on the Boeing 737.

There were three flight attendants onboard Flight 1380, including Rachel Fernheimer, Seanique Mallory and Kathryn Sandoval. Mallory had previously worked as a customer survice agent before becoming a flight attendant, and Sandoval had just six weeks of experience working for Southwest Airlines.

Accident
At 11:03 am Eastern Daylight Time, the aircraft was climbing through 32,500 feet (9906 m) 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, causing damage to the leading edge of the left wing, the left side of the fuselage, and the left horizontal stabilizer. A portion of the fan cowl and latching mechanism struck the passenger window next to seat 14A and caused a rapid decompression. The flight crew conducted an emergency descent and diverted the flight to Philadelphia International Airport. One passenger sitting next to the broken window suffered fatal injuries while eight passengers sustained minor injuries.

The flight crew reported that immediately after the engine failure the aircraft yawed and set off several cockpit emergency alarms; 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.

In the cabin flight attendants helped people secure oxygen masks. Rachel Fernheimer was the first flight attendant to arrive at row 14, where passenger Jennifer Riordan's upper body had been pulled outside. Passenger Hollie Mackey had moved from her aisle seat to the middle seat and grabbed Riordan's belt loops in an attempt to pull her back in, but was unseccessful. Fernheimer joined in and grabbed onto Riordan's thighs, while passengers Tim McGinty from row 15 and Andrew Needum from row 7 joined in the effort. Needum, laid across the laps of passengers in the aisle and center seats with another passenger holding on to his ankles, put all of his weight into pulling Riordan back inside, but he had no leverage. Needum told Mackey and the passenger in the aisle seat to move, so Fernheimer took them to the flight attendant's jump seats at the front of the plane. McGinty and Needum tried once more to pull Riordan back in, but was again unsuccessful. Flight attendant Seanique Mallory called the flight deck, informed the pilots about the situation in the cabin and asked them to slow down so Riordan could be pulled back inside. Passengers in the cabin felt the deceleration as McGinty and Needum pulled Riordan back inside. Riordan was unconscious and bleeding. Needum checked for a pulse while Mallory put out a call for anyone who knew CPR. A retired school nurse named Peggy Phillips was on board, and she and Needum performed CPR while Fernheimer retrieved the emergency medical kit.

The captain asked the air traffic controller for a course diversion. She initially requested a diversion to the nearest airport, but then decided that Philadelphia International Airport was best equipped to handle the emergency. The controller quickly provided vectors Philadelphia International Airport. The flight crew reported initial communications difficulties because of the loud noises, distraction, and the wearing of 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 up the approach and expedite landing.

Flight 1380 landed on runway 27L at Philadelphia International Airport at 11:23 am Eastern Daylight Time. After landing the pilots set the flaps to 40 degrees, providing a slide to the ground in case anyone opened the over-wing exits and tried to get out. Flight attendents were instructed to put the girt bars up to prevent the slides from deploying when the the aircraft doors are opened. Agents from the Federal Bureau of Investigation boarded the plane to investigate whether the explosion was an act of terrorism, which they concluded was not.

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 International (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 as well. 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, Berks County, Pennsylvania, some 60 miles (100 km; 50 nmi) 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) based on it. The CFM service bulletin recommended ultrasonic inspections of all fan blades on engines that have 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 must 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) 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 a follow up airworthiness directive (AD), 2018-09-10, which expanded the inspections on CFM56-7B engines beyond the original EAD. The new AD required inspections of engines with lower cycles, and introduced repeat inspection requirements, as well. Effective with the issuance of this AD, operators are required to perform detailed inspections on each fan blade before it accumulates 20,000 cycles since new, or within 113 days, whichever occurs later. If cycles since new on a fan blade are unknown, then the airline is to perform an initial inspection within 113 days from the effective date of this AD. Thereafter, repeat this inspection no later than 3,000 cycles since the last inspection. If any unserviceable fan blade is found, it must be removed from service before further flight. The FAA estimates this AD affects 3,716 engines installed on aircraft of U.S. registry at an estimated cost of US$8,585 per blade replacement.

On June 7, 2018, the aircraft involved in the accident was flown from Everett to Southern California Logistics Airport in Victorville, California for storage. As of April 2020, the aircraft has not been flown.

Preliminary findings
On May 3, 2018, the NTSB released an investigative update with preliminary findings:


 * Initial examination of the aircraft revealed that the majority of the inlet cowl was missing, including the entire outer barrel, the aft bulkhead, and the inner barrel forward of the containment ring. The inlet cowl containment ring was intact, but exhibited numerous impact witness marks. Examination of the fan case revealed no through-hole fragment exit penetrations; however, it did exhibit a breach hole that corresponded to one of the fan blade impact marks and fan case tearing.
 * The number-13 fan blade had separated at the root; the dovetail remained installed in the fan disk. Examination of the fan blade dovetail exhibited features consistent with metal fatigue initiating at the convex side near the leading edge. Two pieces of the fan blade were recovered from within the engine, between the fan blades and the outlet guide vanes. One piece was part of the blade airfoil root that mated with the dovetail that remained in the fan disk; it was about 12 inches (30 cm) spanwise and full width and weighed about 6.825 pounds (3.096 kg). The other piece, identified as another part of the airfoil, measured about 2 inches (5 cm) spanwise, appeared to be full width, was twisted, and weighed about 0.650 pounds (0.295 kg). All the remaining fan blades exhibited a combination of trailing edge airfoil hard-body impact damage, trailing edge tears, and missing material. Some also exhibited airfoil leading-edge tip curl or distortion. After the general in situ engine inspection was completed, the remaining fan blades were removed from the fan disk and an ultrasonic inspection was performed, with no other cracks found.
 * The number-13 fan blade was examined further at the NTSB materials laboratory. The fatigue fracture propagated from multiple origins at the convex side and was centered about 0.568 inches (14.43 mm) aft of the leading-edge face of the dovetail, and was located 0.610 inches (15.49 mm) outboard of the root end face. The origin area was located outboard of the dovetail contact face coating, and the visual condition of the coating appeared uniform with no evidence of spalls or disbonding. The fatigue region extended up to 0.483 inches (12.27 mm) deep through the thickness of the dovetail and was 2.232 inches (5.669 cm) long at the convex surface. Six crack arrest lines (not including the fatigue boundary) were observed within the fatigue region and striations consistent with low-cycle fatigue crack growth were observed.
 * The accident engine's fan blades had accumulated more than 32,000 engine cycles since new. Maintenance records showed that the fan blades had been periodically lubricated as required, and that they were last overhauled 10,712 engine cycles before the accident. At the time of the last blade overhaul (November 2012), they were inspected using visual and fluorescent penetrant inspections. After an August 27, 2016, accident in Pensacola, Florida, in which a fan blade fractured, eddy-current inspections were incorporated into the overhaul process requirements. In the time since the fan blades' overhaul, the blade dovetails had been lubricated six times. At the time each of these fan blade lubrications occurred, the fan blade dovetail was visually inspected as required.
 * The remainder of the airframe exhibited significant impact damage to the leading edge of the left wing, left side of the fuselage, and left horizontal stabilizer. A large gouge impact mark, consistent in shape to a recovered portion of fan cowl and latching mechanism, was adjacent to the row 14 window, which was missing. No window, structural, or engine material was found inside the cabin.

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 had been and had failed, as was the case in this accident, that it would 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 seven safety recommendations to the FAA.

Final report
On November 19, 2019, following the aforementioned 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."



Aftermath
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, Lilia Chavez, a passenger on board the flight, filed a lawsuit against Southwest Airlines, claiming that she suffers from post-traumatic stress disorder since the accident. Her lawsuit was later settled.