Southwest Airlines Flight 1380 facts for kids
N772SW, the aircraft involved in the accident photographed in 2016
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| Accident summary | |
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| Date | April 17, 2018 |
| Summary | Engine failure leading to rapid depressurization |
| Place | Over Pennsylvania, United States |
| Passengers | 144 |
| Crew | 5 |
| Injuries (non-fatal) | 8 |
| Fatalities | 1 |
| Survivors | 148 |
| Aircraft type | Boeing 737-7H4 |
| Airline/user | Southwest Airlines |
| Registration | N772SW |
| Flew from | LaGuardia Airport, New York City, New York, United States |
| Flying to | Dallas Love Field, Dallas, Texas, United States |
Southwest Airlines Flight 1380 was a Boeing 737-7H4 that experienced a contained engine failure in the left CFM56-7B 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, causing explosive depressurization of the aircraft after damaging a cabin window. Other fragments caused damage to the wing. The crew conducted an emergency descent and diverted to Philadelphia International Airport. One passenger was partially ejected from the aircraft and later died. Eight other passengers received minor injuries. The aircraft was substantially damaged.
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 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 this engine because it 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.
Contents
Background
Flight 1380 was a regularly scheduled passenger flight from New York LaGuardia Airport to Dallas Love Field. The aircraft was a Boeing 737-7H4 with the registration N772SW, in service with Southwest Airlines since its manufacture in 2000. It was powered by CFM56-7B engines.
Tammie Jo Shults, aged 56, a former United States Navy fighter pilot, was the captain of the flight. 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, was the first officer. Captain Shults had been with Southwest Airlines since 1994 and had logged a total 11,715 flight hours, including 10,513 hours on the Boeing 737. First Officer Ellisor had been with the airline since 2008 and had 9,508 flight hours, with 6,927 hours on the Boeing 737. Five crew members and 144 passengers were on board.
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, Berks County, Pennsylvania, 60 miles (97 km; 52 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) 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 accumulateed 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.
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 2021, 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, 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.
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.
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, 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.
Captain Shults wrote a book about the incident titled Nerves of Steel. The book was published in the United States on October 8, 2019.
The aircraft, N772SW, a Boeing 737-7H4, 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. It has had its Southwest titles removed but remains in the basic Southwest livery.
Images for kids
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N772SW, the aircraft involved, seen at McCarren International Airport, in 2013, while still wearing its Canyon Blue livery.
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NTSB inspectors indicating the location of the missing fan blade
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Pieces of the engine nacelle were found in a Pennsylvania field.
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See also
In Spanish: Vuelo 1380 de Southwest Airlines para niños
