After investigating an engine blowout that killed a Southwest Airlines passenger last year, federal security officials said Tuesday that Boeing should be ordered to overhaul the engine casing on its 737 NG aircraft, and airlines should retrofit more than 6,800 aircraft currently is operating worldwide.
In a frightening incident in April 2018, the left engine of 737 exploded and flying metal broke a passenger window. Jennifer Riordan, 43, the mother of two children, was partially sucked out of the plane.
The cause was a fan blade in the left engine that broke off and sent metal scrapers that raced through the engine compartment, pierced the fuselage and caused the cabin to decompress. Part of the bonnet hit and broke the window at Riordan's seat.
She died as a result of personal injury, the only fatal accident on board an American airline in the last decade.
The tragedy raised questions about safety oversight because of a similar engine explosion on another Southwest aircraft 1[ads1]9 months earlier. Following the previous incident, the Federal Aviation Administration (FAA) mandated inspections of engine fan blades – but the inspections failed to detect the broken fan blade that caused that fatal accident.
During a public hearing on Tuesday, NTSB) released its investigation of Southwest flight 1380, which departed from New York City on its way to Dallas, but diverted to Philadelphia after the engine explosion.
The NTSB issued a series of recommendations, including that the FAA requires Boeing to redo the enclosure around the engine to prevent hot metal shrapnel penetration in the event of an engine explosion.
On Flight 1380, it was the disintegration of the fan comb that did the most damage. It is the middle part of the pod that revolves around the engine. a section that opens on the hinges to provide access to maintenance.
The design requirements for the engine housing – known as the nacelle – were developed by Boeing. The 737 NG nacelles are then designed and built by a division of United Technologies.
737 NG, with nearly 7000 flights worldwide, is the model before the 737 MAX. MAX has another engine and casing and is not affected.
Boeing said it "is working on a design enhancement that will fully meet the NTSB security recommendation."
"Once approved by the FAA, that design change will be implemented in the existing 737 NG fleet," Boeing added.
The NTSB said the accident investigation revealed that when the fan blade broke, it hit the casing of a special The FAA recommended that other aircraft / engine combinations have similar critical locations where the casing may need to be strengthened.
A similar blowout in 2016
The NTSB found no fault with the Southwest.
Captain Tammie Jo Shults , a former Navy fighter pilot, guided the plane with 144 passengers and five crew to a safe landing 20 minutes after the explosion.
However, the tragedy followed a similar engine blowout on a Southwest flight from New Orleans to Orlando in August 2016 that departed Pensacola, Florida, 737 cabin decompressed, but no one was injured.
At the NTSB hearing Tuesday, FAA security engineer Christopher Spinney said the Pensacola incident was first destroyed the fan blade on a CFM56-7B engine of 300 million flight hours.
Because it was such a rare event and only resulted in a slow depressurization, the FAA first considered "that we would require some corrective action, in that it was a precarious condition, but we also decided we had some time," he said Spinney. 19659002] The FAA found that the reason why the Philadelphia engine failed to be metal fatigue cracks at the root of a fan blade, and it ordered inspections of specific fan blades on the CFM56-7B engines that powered the model 737. The blade that broke on flight 1380 was not part included in the directive.
In November 2017, a crack was found in another fan blade that was not covered by the original mandate, and the FAA determined that the error could potentially occur in any fan blade on a CFM56 -7 B engine.
On Tuesday, the FAA said it was working with engine manufacturer CFM International – a joint venture between GE and Safran in France – to develop and approve a comprehensive inspection program for all engine fan blades.
Before the fatal accident, it was preparing, but had not completed an airworthiness directive to mandate the increased inspections.
The FAA added that the CFM had already recommended to the airlines the same inspection regime and that Southwest Airlines and other airlines were proactively performing the inspections – even though they were not fully completed.
Three days after Riordan's accident and death, the FAA issued an Emergency Airworthiness Directive, which was extended the following month to require airlines to conduct detailed inspections on each fan blade before fan blade accumulates 20,000 cycles of take-off and landing, and to repeat inspection at the latest every 3,000 cycles.
FAA's Spinney told NTSB on Tuesday that the blowout over Pensacola had been so unusual that "we thought it was an anomaly."
"When the Philadelphia incident happened, we realized in coordination with our engine experts that the Pensacola incident was not, in fact, an anomaly. That's when we took immediate action with the Airworthiness Directive on the engine."
The FAA said Tuesday that "the relevant The CFM engines meet FAA safety standards. "
Boeing also said that" all 737 NGs are safe to continue operating normally as the problem is completely mitigated by fan blade inspections "in the FAA directives that followed the fatal accident.
Southwest i a statement said that it will review the NTSB recommendations and will continue "ongoing work with the manufacturers to prevent a similar incident from ever happening again."
The NTSB recommendation contributes to the rising afflictions of the jet family 737.
MAX is still grounded eight months after the second of two fatal accidents, and at 737 NG, cracks were recently discovered in a structural section called "jam cucumber, a heavy metal attachment between wing and fuselage.
Last month, the FAA issued an airworthiness directive requiring inspection in the next 1,000 cycles of pickles on all 737 NGs that have flown more than 22,600 cycles and instant inspection for those with more than 30,000 cycles.
Rob Morris, consultant to Cirium, an aviation data and analysis company, estimates that nearly 1,800 aircraft will require this inspection. From the beginning of this month, he said 1,100 aircraft had been inspected, 50 of which were found to need repairs that will take two to three weeks.
Airlines affected by pickle fork cracks include Southwest and Ryanair, each of which has two 737s under repair.