Boeing says it’s fixing 737 NG part NTSB wants redesigned

Bloomberg

The US National Transportation Safety Board (NTSB) recommended that the Boeing Co 737 NG (Next Generation) be redesigned to prevent a repeat of a fatal accident last year in which an engine part broke off in flight, killing a passenger.
More than 7,000 so-called 737 Next Generation planes could be affected by the recommendation that the inlet to the engines be redesigned to contain parts that come loose in a failure.
The NTSB called on the Federal Aviation Administration (FAA) to require the repair be installed on new 737 NG aircraft and that it be retrofitted onto the thousands of planes in service.
“These recommendations show the way towards greater safety even when a fan-blade-out event occurs,” NTSB chairman Robert Sumwalt said at the conclusion of the meeting.
Boeing said in an emailed statement it is introducing enhancements to the part of the engine that failed in order to improve its ability to withstand a broken fan blade.
“Boeing is committed to working closely with the FAA, engine manufacturers, and industry stakeholders to implement enhancements that address the NTSB’s safety recommendations,” the company said in the statement. The FAA said it will review and respond to the NTSB
recommendations.
Boeing and the FAA said a significant amount of the risk has been eliminated because of newer, more thorough inspections of the fan blades. Previous inspections missed cracks that could lead to failures.
FAA, working with CFM, has issued several orders for inspections using different technology that works better to sense
hidden cracks on the more
than 350,000 fan blades on CFM56-7B engines.
However, blades can fail for several reasons, such as when planes hit birds, and the inspections can’t eliminate all the risk of such an event occurring.
The safety board issued the recommendation after a hearing on the April 17, 2018, incident in which a woman was partially sucked out from the Southwest Airlines jet and had to be pulled back into the plane by fellow passengers.
A fan blade on an engine made by CFM International Inc broke off, triggering the damage, the NTSB concluded.
The NTSB stopped short of asking for changes on other aircraft and engine combinations, but asked the FAA to improve how the structure at the front of the engine — a curved surface that provides a smooth flow of air into the power plants — is designed in the future.
The NTSB also urged the European Aviation Safety Agency to adopt the suggested improvements. While FAA has no legal authority outside the US, other nations typically follow its lead.
The NG model is a predecessor to Boeing’s 737 Max that has been grounded since the second of two deadly crashes in March.
At least part of the reason that the engine failure caused so much damage is the unusual shape of the structure outside 737 NG engine.
Instead of being circular, as is the case on most models, the NG is flattened on the bottom so the engine can fit on its relatively low wings.