Boeing should redesign engine covers on all its 737NG aircraft following an accident that killed a mother-of-two, investigators have said.
The National Transportation Safety Board (NTSB) looked at the April 2018 incident, which saw an engine fan blade break and its debris pierce the engine cover before hitting the fuselage near a window.
The window shattered, leading to rapid depressurisation and Jennifer Riordan, a 43-year-old banker and mother of two from Albuquerque, New Mexico, being partially sucked out of the plane.
Other passengers managed to pull her back inside but efforts to save her life were unsuccessful.
Southwest Airlines Flight 1380 had been travelling from New York City’s LaGuardia to Dallas when it made an emergency landing in Philadelphia with 144 passengers and five crew on board.
The NTSB said the 24 blades in the plane’s CFM-56-7B engine were 18 years old and had been used on more than 32,000 flights before that day.
But one of the blades was already cracked when it was last overhauled and the damage was not spotted. Inspections are now more rigorous and regular.
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NTSB chairman Robert Sumwalt said engine and aircraft manufacturers should develop stronger designs for engine casing to prevent broken fan blades from causing such a terrible tragedy again. Older aircraft of the same model should then be retro-fitted with the new design, he said.
He added: “That translates to a better chance that damage to the aircraft will be minimised during a (broken fan blade) event, improving the safety of the flying public.”
The NTSB did not say the planes should be grounded, adding that fan blades are being inspected more often now, usually every nine to 12 months.
Boeing also said the improved inspections meant its planes were safe but added that it is working on a “design enhancement” to address the recommendations. Southwest and the Federal Aviation Authority said they would review the findings.
The recommendations cover the NG (Next Generation) versions of the 737 but do not cover its successor the Boeing 737 MAX which was grounded following the fatal crashes of Lion Air flight 610 in Indonesia on 29 October 2018 and Ethiopia Airways in March this year.
The NTSB praised flight 1380’s pilots, former Navy pilot Tammie Jo Shults, and the first officer, former Air Force pilot Darren Ellisor, for managing to land the plane safely, despite a harrowing emergency descent from 32,000ft.
The NTSB said the pair had used unusual settings for the plane’s flaps because they feared losing control if they flew too slowly.
Mr Sumwalt said of Ms Shults: “Basically, she used airmanship, she used judgement, because she felt that was the safest thing to do.” He said this proved the value of well-trained and experienced pilots.
After the recommendations were reported, Mrs Riordan’s family gave a statement to ABC News: “Jennifer’s family would like to thank the NTSB for the investigation and hope that these recommendations are taken seriously to ensure no other family has to go through this type of tragedy ever again.
“In honour of Jennifer, please remember to be kind, loving, caring and sharing.”