Federal aviation investigators say Boeing Co. needs to redesign a flawed engine casing after a deadly accident on Southwest Airlines flight 1380 last year.
Ending a 19-month investigation into the flight that killed passenger Jennifer Riordan when she was partially sucked out a broken window, the National Transportation Safety Board said Tuesday that the design of the fan cowl was to blame for the damage from the accident, as well as a cracked fan blade that broke during flight.
“The blade was contained,” said NTSB vice chairman Bruce Landsberg. “But unfortunately, the cowling was not.”
The NTSB said Boeing needs to redesign the fan cowl and that Boeing 737 NG customers should retrofit planes with the new parts.
Southwest Airlines flight 1380 had to make an emergency landing on April 17, 2018, after a fan blade broke, causing the engine to blow apart. Debris slammed against the plane and broke a window. Riordan’s death was the first on-board fatality in Southwest’s then 47-year history.
The engine’s explosion caused rapid depressurization inside the plane, which was traveling from New York to Dallas Love Field. The pilots said the plane was difficult to control as they diverted to land in Philadelphia.
Meanwhile, passengers and crew struggled to pull Riordan back inside the plane. Riordan, a 43-year-old bank executive from New Mexico, suffered fatal injuries. Eight passengers had minor injuries.
The NTSB also said airplane and engine makers need to rethink testing because the fan blade did not break off from the engine in a way anticipated during design and testing. Engines are meant to contain incidents such as a fan blade breaking, but the fan cowl failed, investigators said.
The fan casing was a new design on the Boeing 737 NG. It’s oblong on the bottom so it doesn’t scrape the ground.
Boeing also had to redesign engines and wings to accommodate larger engines on its future 737 Max model, which has been grounded because of two crashes tied to the larger engines and a software fix meant to make the plane easier to fly.
Boeing spokesman Peter Pedraza said the company is working on “enhancements” to the 737 NG cowls. He said all Boeing 737 NG planes are safe to fly and the cowl problem does not affect the Boeing 737 Max line.
“Boeing is committed to working closely with the FAA, engine manufacturers, and industry stakeholders to implement enhancements that address the NTSB’s safety recommendations,” Pedraza said in an email.
NTSB chairman Robert Sumwalt also said Southwest identified 16 other planes in its fleet with cracked engine fan blades out of 23 total.
The NTSB criticized Southwest Airlines flight attendants for not returning to jumpseats during landing but acknowledged it might have been hard to hear commands from the cockpit. The agency also said Capt. Tammie Jo Shults and First Officer Darren Ellisor didn’t complete all the flight-required checklists for an emergency situation, although the duo were commended for guiding the plane to safety as they struggled to control the aircraft without an engine and with a hole in the fuselage.
“And I’m not one to ever advocate skipping checklists … but in a situation like this, frankly, the most important thing to do is to get the airplane on the ground, keep the blue side up, get the landing gear down, put it on the concrete. And they did that.”
Southwest spokesman Chris Mainz said the company has started an accelerated program for ultrasonic testing on questionable turbine blades. It finished a complete inspection of all 1,600 blades on Southwest planes in August 2018.
“We look forward to reviewing the NTSB’s recommendations and working with the manufacturers to prevent this type of event from ever happening again,” Mainz said in a statement. “We support the actions of our crews, and we remain forever grateful for their professional and heroic actions. Southwest will also fully support any regulatory changes that may further enhance aviation safety.”
The cracked engine blade in question was manufactured by CFM International, which is co-owned by GE. CFM has called for engine owners to increase inspections on engines, a recommendation that came from the NTSB after another Southwest Airlines flight in 2016 had a similar cracked blade problem that caused the loss of an engine. No one was hurt in that incident.