Federal Investigators Detail Probe of Southwest’s Emergency Landing at PHL

The National Transportation Safety Board says the fan blades in Flight 1380’s failed engine made more than 32,000 trips.

Image via 6ABC Action News

Captain Tammie Jo Schults, a former Navy pilot, remained calm after taking over the controls from her co-pilot aboard the sputtering Southwest Flight 1380 last month. With its engine blown and cabin breached with damage to a passenger window, the National Transportation Safety Board says Schults coolly requested that air traffic controllers permit an emergency landing at the nearest airport before settling on Philadelphia International on April 17th.

More details of that harrowing flight have come to light with the NTSB’s update of its investigation into the incident, which resulted in the death of a 43-year-old woman.

While it was initially believed that a detached fan blade directly caused the crack in the window that the woman was partially sucked out of, the federal agency has now determined that a piece of the engine called the inboard fan cowl was what actually struck the aircraft.

Photo courtesy of the NTSB.

NTSB investigators found that a faulty engine fan blade snapped off due to metal fatigue, which triggered a chain of events that eventually led to the inboard fan cowl hitting the aircraft. According to the NTSB report, Southwest maintenance records show that the fan blades in Flight 1380’s failed engine had made more than 32,000 trips in their lifetime. All fan blades are inspected only by sight, with fluorescent dye used to find any surface defects.

Since the emergency landing, Southwest says crew members have examined more than 25,000 blades in its fleet and found only one other that showed signs of cracking. The Federal Aviation Administration has ordered the inspection of more than 3,700 planes for defective fan blades in response.

The report also provides details about what was happening inside the cockpit and cabin during the incident:

During interviews, the flight crew stated the climbout from LaGuardia was normal with no indications of any problems; the first officer was the pilot flying and the captain was the pilot monitoring. They reported experiencing a sudden change in cabin pressure, aircraft yaw, cockpit alarms, and a “gray puff of smoke.” They donned their oxygen masks, and the first officer began a descent.

Flight data recorder data showed that the left engine parameters all dropped simultaneously, vibration increased, and, within 5 seconds, the cabin altitude alert activated. The FDR also indicated that the airplane rolled left to about 40 degrees before the flight crew was able counter the roll with control inputs. The flight crew reported that the airplane exhibited handling difficulties throughout the remainder of the flight…

The flight crew reported initial communications difficulties because of the loud sounds, distraction, and wearing masks, but, as the airplane descended, the communications improved. The captain initially was planning on a long final approach to make sure they completed all the checklists, but when they learned of the passenger injuries, she decided to shorten the approach and expedite landing.

The following companies/agencies assisted the NTSB in its probe: the FAA, Southwest Airlines, GE Aviation, Boeing, the Aircraft Mechanics Fraternal Association, the Southwest Airlines Pilots Association, Transport Workers Union Local 556, and UTC Aerospace Systems.