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FAA issues new airworthiness directive for all CFM56-7B engines in wake of Southwest 1380 accident

The U.S. FAA issued a new airworthiness directive (AD) for all CFM International S.A. (CFM) Model CFM56-7B engines in the wake of the April 17 uncontained engine failure accident involving a Southwest Airlines Boeing 737-700.

The AD 2018-09-10 requires initial and repetitive inspections of the concave and convex sides of the fan blade dovetail to detect cracking and replacement of any blades found cracked.

The AD is effective May 14, 2018.

In response to the Southwest Airlines accident, the FAA issued Emergency AD 2018-09-51, to address certain high-time CFM56-7B engines, specifically including those with 30,000 or more total accumulated flight cycles since new. AD 2018-09-51 requires a one-time ultrasonic inspection (USI) of the concave and convex sides of the fan blade dovetail.

Since the issuance of that AD, the FAA states it has been working with CFM to develop an additional compliance plan to address the risk of fan blade failure for the entire CFM56-7B fleet. This AD addresses the unsafe condition affecting CFM56-7B engines by requiring initial and repetitive inspections of fan blades based on accumulated fan blade cycles.

NTSB: Pilots struggled to control damaged Southwest jet DALLAS (AP) - The pilots of a Southwest Airlines jet struggled to handle the plane after an engine blew apart at 32,000 feet over Pennsylvania last month. Investigators say the captain, Tammie Jo Shults, took over control from the co-pilot. She first asked air traffic controllers for permission to land at the nearest airport, but then aimed for Philadelphia, where the crippled plane made an emergency landing. The National Transportation Safety Board provided new details Thursday on the fatal accident aboard Southwest Flight 1380 on April 17. Investigators say metal fatigue caused the No. 13 fan blade in the left engine to separate at 10:03 a.m. that day. Engine debris damaged the wing and window of the Boeing 737. Crew members told the NTSB they heard a loud sound, felt vibration and saw a "gray puff of smoke." "The flight crew reported that the airplane exhibited handling difficulties throughout the remainder of the flight," the NTSB report said. Flight records show the plane descended nearly 20,000 feet in a matter of minutes. Flight attendants were assisting passengers with their oxygen masks when they found Jennifer Riordan, a passenger in row 14, partially sucked out of the airplane. Engine maker CFM International increased the frequency of recommended inspections in the wake of Flight 1380, according to the NTSB report. The left engine had been last overhauled 10,712 cycles before the accident, according to maintenance records. CFM now recommends inspections occur every 3,000 intervals in the future, according to an April 20 bulletin. The NTSB report indicates the engine had been properly inspected and lubricated before the accident. https://www.wfaa.com/article/news/nation/ntsb-pilots-struggled-to-control-damaged-southwest-jet/287-548568060 Back to Top

NTSB issues an investigative update on Southwest Airlines flight 1380 accident The U.S. NTSB issued an investigative update regarding the April 17 uncontained engine failure accident involving Southwest Airlines flight 1380. On April 17, 2018, a Boeing 737-700 experienced a failure of the left CFM-56-7B engine and loss of engine inlet and cowling during climb about flight level 320. Fragments from the engine inlet and cowling struck the wing and fuselage, resulting in a rapid depressurization after the loss of one passenger window. The flight crew conducted an emergency descent and diverted into Philadelphia International Airport (KPHL), Pennsylvania. Of the 144 passengers and five crewmembers onboard, one passenger received fatal injuries and eight passengers received minor injuries. Initial examination of the airplane revealed that the majority of the inlet cowl was missing, including the entire outer barrel, the aft bulkhead, and the inner barrel forward of the containment ring. The inlet cowl containment ring was intact but exhibited numerous impact witness marks. Examination of the fan case revealed no through-hole fragment exit penetrations; however, it did exhibit a breach hole that corresponded to one of the fan blade impact marks and fan case tearing.     Figure 1. Damage to cowl - inboard The No.13 fan blade had separated at the root; the dovetail remained installed in the fan disk. Examination of the No. 13 fan blade dovetail exhibited features consistent with metal fatigue initiating at the convex side near the leading edge. Two pieces of fan blade No. 13 were recovered within the engine between the fan blades and the outlet guide vanes. One piece was part of the blade airfoil root that mated with the dovetail that remained in the fan disk; it was about 12 inches spanwise and full width and weighed about 6.825 pounds. The other piece, identified as another part of the airfoil, measured about 2 inches spanwise, appeared to be full width, was twisted, and weighed about 0.650 pound. All the remaining fan blades exhibited a combination of trailing edge airfoil hard body impact damage, trailing edge tears, and missing material. Some also exhibited airfoil leading edge tip curl or distortion. After the general in-situ engine inspection was completed, the remaining fan blades were removed from the fan disk and an ultrasonic inspection was performed consistent with CFM International Service Bulletin 72-1033. No cracks were identified on the remaining blades. The No. 13 fan blade was examined further at the NTSB Materials Laboratory. Fatigue fracture features emanated from multiple origins at the convex side and were centered about 0.568 inch aft of the leading edge face of the dovetail and were located 0.610 inch outboard of the root end face. The origin area was located outboard of the dovetail contact face coating, and the visual condition of the coating appeared uniform with no evidence of spalls or disbonding. The fatigue region extended up to 0.483 inch deep through the thickness of the dovetail and was 2.232 inches long at the convex surface. Six crack arrest lines (not including the fatigue boundary) were observed within the fatigue region. The fracture surface was further examined using a scanning electron microscope, and striations consistent with low-cycle fatigue crack growth were observed. The accident engine fan blades had accumulated more than 32,000 engine cycles since new. Maintenance records indicated the accident engine fan blades had been periodically lubricated as required per the Boeing 737-600/700/800/900 Aircraft Maintenance Manual. According to maintenance records, the fan blades from the accident engine were last overhauled 10,712 engine cycles before the accident. At the time of the last blade overhaul (November 2012), blades were inspected using visual and fluorescent penetrant inspections. After an August 27, 2016, accident in Pensacola, Florida, in which a fan blade fractured, eddy current inspections were incorporated into the overhaul process requirements. In the time since the fan blade overhaul, the accident engine fan blade dovetails had been lubricated 6 times. At the time each of these fan blade lubrications occurred, the the fan blade dovetail was visually inspected as required for the fan blades installed in the accident engine. The NTSB materials group is working to estimate the number of cycles associated with fatigue crack initiation and propagation in the No. 13 fan blade and to evaluate the effectiveness of inspection methods used to detect these cracks. The remainder of the accident airplane's airframe exhibited significant impact damage to the leading edge of the left wing, left side of the fuselage, and left horizontal stabilizer. A large gouge impact mark, consistent in shape to a recovered portion of fan cowl and latching mechanism, was adjacent to the row 14 window; the window was entirely missing. No window, airplane structure, or engine material was found inside the cabin.  Picture of window 14 with portion of engine inboard fan cowl. Three flight attendants were assigned to the flight, and an additional SWA employee was in a jumpseat in the cabin. During interviews, the flight attendants and the employee reported that they heard a loud sound and experienced vibration. The oxygen masks automatically deployed in the cabin. The flight attendants retrieved portable oxygen bottles and began moving through the cabin to calm passengers and assist them with their masks. As they moved toward the mid-cabin, they found the passenger in row 14 partially out of the window and attempted to pull her into the cabin. Two male passengers helped and were able to bring the passenger in. The investigation is ongoing. https://news.aviation-safety.net/2018/05/03/ntsb-issues-an-investigative-update-on-southwest-airlines-flight-1380-uncontained-engine-failure-accident/ Back to Top

Failed Southwest Air Jet Engine Had Passed Seven Inspections By Alan Levin NTSB releases preliminary report on April 17 fatal accident More sophisticated testing ordered by FAA on similar engines NTSB investigators examine damage to the engine belonging Southwest Airlines Flight 1380 in Philadelphia on April 17, 2018. Photographer: Keith Holloway/National Transportation Safety Board The fan blade that failed on a Southwest Airlines Co. plane last month, killing a passenger, had been inspected seven times since late 2012 but without the sophisticated technology airlines are now under orders to use. The inspections relied on visual observations and there were no reports of cracks, according to a preliminary report issued Thursday by the National Transportation Safety Board. The investigation of the April 17 Southwest flight is one of the most significant in years, since it raises questions about the safety of the CFM56-7B engine, one of the world's most popular. Before engines like this get approval from aviation regulators, manufacturers must demonstrate that failed fan blades won't trigger extensive damage if they break loose. Since a similar fan blade failure on another Southwest plane in 2016, engine maker CFM International Inc. has urged airlines to use either ultrasound or electric-current tests designed to find cracks beneath the surface. The Federal Aviation Administration has issued two orders since April's accident on Flight 1380 for the more sophisticated testing of fan blades, touching off a rush by airlines to examine thousands of the blades. The orders call for the inspection of blades that have made at least 20,000 flights by the end of August. If a blade's number of flights isn't known, it must also be tested by the same deadline. Failed Blade's History The failed blade had made more than 32,000 flights, according to the NTSB. Southwest says it expects to complete all the inspections, even those with fewer than 20,000 flights, of its fleet in coming weeks. The most recent extensive inspection of the failed blade occurred in November 2012, using a dye designed to highlight small cracks on the surface. The engine had made 10,712 cycles -- starting and stopping the engine, usually associated with a flight -- since then, according to the NTSB. For the six inspections since 2012, the blades were lubricated and mechanics examined them visually for flaws. Southwest said in a statement on Thursday that the company was continuing "to cooperate fully with the National Transportation Safety Board's (NTSB) ongoing investigation into Flight 1380." CFM is a joint venture between General Electric Co. and France's Safran SA. A passenger, Jennifer Riordan, who was a vice president at Wells Fargo & Co. in New Mexico, was killed after being partly sucked out of the shattered window. The plane, a Boeing Co. 737-700 bound for Dallas from New York's LaGuardia airport, made an emergency landing in Philadelphia. While there have been fatal crashes involving cargo haulers, foreign airlines and charter operators, it was the first death of a passenger on a U.S. airline since 2009. Questions Remain The preliminary report doesn't say why the crack grew large enough for the blade to snap off or whether use of more sophisticated testing before the accident could have prevented the failure. When the blade broke loose -- the result of a crack that gradually expanded under the stresses of multiple flights -- it bounced forward and collided with the relatively unprotected engine inlet, tearing it apart and sending shrapnel into the fuselage and wing. Investigators may have identified the part that shattered the window. A metal piece that included a latching mechanism, which was recovered after the accident, matches "a large gouge impact mark" adjacent to the row 14 window that broke, NTSB said. An examination of the failed blade under an electron microscope showed evidence of "low-cycle fatigue," the NTSB said. That suggests that the crack grew relatively quickly, but investigators didn't provide any timeline. All the remaining blades on the failed engine were removed and tested using an ultrasonic device that can detect flaws beneath the titanium surface, but no additional cracks were found, NTSB said. The engine's containment shield, designed to prevent the kind of widespread damage that occurred in the accident, did block blade fragments from escaping. However, the majority of material at the front of the engine known as the "inlet cowl" was missing. The report also includes new information about what happened on the plane in the moments after the failure. The 737 banked more than 40 degrees to the left. The pilots recovered, but had to fight the controls. "The flight crew reported that the airplane exhibited handling difficulties throughout the remainder of the flight," the NTSB said. The plane's three flight attendants told investigators that they donned oxygen masks after the plane lost pressure and began moving through the cabin to assist passengers. That's when they noticed that Riordan had been sucked through the window. "As they moved toward the mid-cabin, they found the passenger in row 14 partially out of the window and attempted to pull her into the cabin," the report said. "Two male passengers helped and were able to bring the passenger in."