| Date: | Tuesday 17 April 2018 |
| Time: | 11:04 |
| Type: |  Boeing 737-7H4 (WL) |
| Owner/operator: | Southwest Airlines |
| Registration: | N772SW |
| MSN: | 27880/601 |
| Year of manufacture: | 2000 |
| Total airframe hrs: | 63043 hours |
| Cycles: | 36728 flights |
| Engine model: | CFMI CFM56-7B24 |
| Fatalities: | Fatalities: 1 / Occupants: 149 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | 105 km NW of Philadelphia, PA -
 United States of America
|
| Phase: | En route |
| Nature: | Passenger - Scheduled |
| Departure airport: | New York-La Guardia Airport, NY (LGA/KLGA) |
| Dallas-Love Field, TX (DAL/KDAL) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
Southwest Airlines flight 1380 diverted to Philadelphia Airport, Pennsylvania, USA, after suffering an in-flight uncontained engine failure.
The aircraft, a Boeing 737-700, originated from New York-La Guardia Airport at 10:43 for a flight to Dallas-Love Field, Texas. About 11:04, when the aircraft was climbing through FL325, the no.1 engine (CFM56-7B24) suffered an uncontained failure. The flight crew noticed that the no.1 engine rpm dropped to zero, as did the oil pressure. The cabin altitude horn sounded and the aircraft experienced a sudden, uncommanded, left roll of a 41° bank angle. The pilots leveled the wing, donned their oxygen masks and initiated an emergency descent. The flight crew then requested air traffic control to give them vectors to the nearest suitable airport.
As a result of the uncontained failure, a fan blade and parts of the engine cowling and engine air inlet cowl had separated. Debris impacted a window frame of row 14, causing the window and frame to break away. This resulted in a decompression of the aircraft. Additional debris impacted and damaged the leading edge of the left hand wing.
The flight was vectored towards Philadelphia Airport, where the crew requested an extended final approach due to concerns of aircraft controllability. It was decided to land with flaps 5 for that reason, and an approach speed of 165 knots. The aircraft landed on runway 27L at 11:19 hours and the aircraft was stopped on a taxiway. ARFF services attended to the no.1 engine while injured passenger who was seated near the lost window was rushed to hospital. The passenger is reported to have died.
Preliminary findings of the NTSB show that the no.13 fan blade of engine no.1 was missing. It appears to have broken away at the hub. There is evidence of metal fatigue in the area where the blade broke.
Also, a part of the no.1 engine cowling was reported to have been found at Burnville, PA.
Probable Cause: 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.
Accident investigation:
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Sources:
Location
Images:
photo (c) NTSB; Philadelphia International Airport, PA (PHL/KPHL); 17 April 2018; (publicdomain)
photo (c) NTSB; Philadelphia International Airport, PA (PHL/KPHL); 17 April 2018; (publicdomain)
photo (c) NTSB; Philadelphia International Airport, PA (PHL/KPHL); 17 April 2018; (publicdomain)
photo (c) NTSB; Philadelphia International Airport, PA (PHL/KPHL); 17 April 2018; (publicdomain)
photo (c) NTSB; near Burnville, PA; 18 April 2018; (publicdomain)
photo (c) NTSB; near Burnville, PA; 18 April 2018; (publicdomain)
photo (c) NTSB; Philadelphia International Airport, PA (PHL/KPHL); April 2018; (publicdomain)
photo (c) NTSB; Philadelphia International Airport, PA (PHL/KPHL); 2018; (publicdomain)
photo (c) NTSB; Philadelphia International Airport, PA (PHL/KPHL); 2018; (publicdomain)
photo (c) Flightaware/Google; 17 April 2018
Revision history:
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