it's Thursday the 5th of December my name is Juan Brown welcome to the Blanco Lirio channel we're back in the hangar today and today we're gonna go over in depth what the NTSB board meeting came up with regarding the Southwest Airlines flight 1380 engine failure due to a fan blade out and subsequent depressurization back in April of 2018 [Music] this was the first fatal accident in the airline industry in the United States in over nine years this is one of only two fan blade out incidents in millions of hours of flying and the cfm56 - 7 B engine series unfortunately both of these happened at Southwest Airlines the first partial fan blade out event happened in 2016 or the aircraft diverted into Pensacola and of course this latest one in April of 2018 where the crew diverted into Philadelphia the Pensacola incident also lost the inlet to the engine but resulted in no injuries after hours of exhaustive investigation the NTSB has come up with 13 findings and seven safety recommendations which we'll talk about today but the bottom line of all of this is the importance of having a current and qualified and experienced crew onboard the aircraft piloting the aircraft to do the right thing when the stuff hits the fan so let's go in and break down exactly what happened to Southwest Airlines flight 1380 from a mechanical point of view but before that we got to review some terminology the Boeing 737 ng or its 700 series of aircraft is powered by the cfm56 - 7 Bravo series of engines these engines have 24 fan blades right at the front of the engine when you look into the engine Inlet that's the first thing you see is that's the high bypass fan blades all 24 of them surrounding those titanium they're solid titanium by the way and I found out in the investigation they're about 52,000 dollars per pair to replace these fan blades of replacement pairs to maintain the balance surrounding the fan blades section is the fan case this is the honeycomb section of material that you see that has a very fairly close tolerance fit around the fan blades the fan case the job of the fan case is to keep any fan blade failure contained within the engine in this case this was technically a contained blade failure the the fan case worked and the fan remained inside the engine however the cowling blew apart resulting in nearly the same destruction as what a uncontained engine failure would produce but technically this was a contained engine failure here you can see the fan case portion of the engine in blue and here's what the fan case looks like on the damaged engine from Southwest flight 1380 outside of the fan case is the cowling or fan cowling and that's divided up into an inboard and outboard section inboard being onboard of the aircraft and outboard on the outboard cowling similar to the mighty Luscombe here it's just a aerodynamic structure or a structure to maintain the aerodynamics of the engine forward of the cowling on the 737 is the inlet and nose ring section the inlet and wrinkle sections shown here in silver and grey and of course is missing on the damaged engine hi in the fan cowling on the 737 is the thrust reverser or thrust reverser section thrust reverser cowling so again here's the inlet section highlighted in yellow the fan cowl section in the middle of the engine and after the fan cowl section is the thrust reverser section now as we've learned from the 737 max series the 737 has developed and changed over the years over I think 16 iterations of the design initially the first 737 the 200 series were powered by small turbojet engines which had round cowlings symmetric cowlings the 737 was intentionally designed to be low to the ground because their ports at the time didn't always have gates and so were they needed to be able to easily load and unload the aircraft using ground equipment and stairs over the years the 737 is designed to bigger and bigger more efficient high-bypass engines the cfm56 series of engine requires a cowling that's flat on the bottom this flat part of the cowling on the bottom is required for ground clearance particularly in crosswind landings when you need to get the wind into the wing to maintain directional control on a crosswind landing so that you're landing more like this and not like this putting a hell of a load on the landing gear while landing in crosswind conditions the critical part that keeps the cowling flat on the bottom on the 737ng series of aircraft is at park called a radial restraint fitting it pulls the bottom of the cowl and attaches it directly to the and case directly connecting the bottom of the fan case to the fan cowling here's the radial restraint fitting circled in orange connecting the bottom of the fan cowl to the fan case so this will all become important as we discuss the sequence of events of what exactly failed on this flight Southwest Airlines flight 1380 departed LaGuardia New York's LaGuardia Airport enroute to Dallas Love Field their hub for Southwest climbing up through the flight levels they were finally cleared to their final altitude of 38,000 feet or flight level 300 about 11 o'clock in the morning as they were climbing through 3 to O or 32,000 feet at 11:03 the number 13 blade lucky number 13 fan blade on the left engine of the 737 let go due to fatigue cracks what they call a low cycle fatigue crack in other words it's cracked before it should have in its lifetime in its time span up the blade the blade failed in the six o'clock position only that one blade failed that one blade hammered down on the six o'clock position it twisted out of the fan case it twisted forward out of the fan case and into the engine Inlet when the fan blade hit the fan case right above the radial restraint fitting the radial restraint fitting did not fail as designers originally thought it would in such a situation the radial restraint fitting initially stayed intact and transmitted the sudden load from the fan case to the fan cowling resulting in the fan cowling latches breaking apart opening up and breaking apart at the same time the displacement wave traveling through the fan casing broke apart the inlet structure of the cowling so within hundredths of a second the fan let's go at the six o'clock position hits the bottom of the fan casing transmits that load through the radial restraint fitting blows apart the cowling and simultaneously blows apart or knocks off the inlet to the engine the fan blade itself slides out through the forward end of the fan case investigators were able to use the scratch marks inside the fan case to determine the trajectory of the fan blade fragments as the fan blade did break up once it hit the case now let me get standby part was that when the cowling flew apart the lower aft inboard section a section of that cowling flew up and hit the fuselage right at the window at row 14 a blowing out that window being at 32,000 feet the fuselage is pressurized and once you hit the window and blow it out air is going to escape and a rapid or almost explosive depressurization by putting the pieces of the puzzle back together after the accident investigators were able to determine that it was this lower aft corner section of the inboard fan cowl that took out the window the window on a modern airliner has three panes on it the outside pane that you can replace as it gets scratched up over de-icing facilities the middle pane which is the structural portion of the window and then an inner pane can get scratched up by the passengers you'll see the little hole in there to allow the pressurization to move through up against the middle pane when that piece of cowling hit that window it blew the whole window out and that's what began the sequence of events that caused the eventual fatality of the passenger in seat 14 a so unlike what you may have heard on media reports it was not a fan blade that hit the window it was a chunk of the cowling that hit the window that broke it other pieces of the cowling hit numerous other sections of the aircraft especially along the leading edge of the slats of the left wing typically as a career when you reach up to cruise altitude it's a time to relax you've gotten through all the pressure of getting out of a busy busy airport on time and it's time to travel bag of peanuts and begin to relax on the cruise portion of the flight this crew faced simultaneously as I counted up nearly five emergencies if you broke him down nearly simultaneously their first indications there was a problem was the loud bang and what appears to be an engine fire on the number one engine followed by almost immediately an altitude a cabin altitude alert warning indicating that the cabin altitude was exceeding 14,500 feet you were depressurizing along with the loss of the engine which any fire indications or activity went out right away and it it soon became an engine severe damage separation event along with the loss of the engine of course they also lost the hydraulics on that side but most noticeable to the crew was the loss of control initially of the aircraft when that engine let go and that cowling let go the engine banked up over 40 degrees a bank it's completely surprising the crew so the crew was stuck struggling with maintaining control of the aircraft maintain control of the aircraft analyzed the situation and land as soon as conditions permit this crew was so impacted with so many emergencies at once that they continued to come back to the maintained aircraft control they didn't have a whole lot of time to analyze the situation and they went straight to land as soon as conditions permit during that process in my previous video I described all the various checklists that are involved with such a scenario and it took me longer to talk our way through those checklists than it did for the crew of flight 13 80 to get the aircraft back safely on the ground they simply did not have to run through all the checklists that are typically run or are required so to speak for such an emergency because eventually the captain has authority to overrule these checklists in the event of an emergency and that's what they did they overrode a lot of these checklists but because of their experience and their ability they were able to a maintain aircraft control and B take care of the critical things through memory by the memorization of the fundamental steps in such an emergency they got the engine shut down or caged as we call it a secured in less than a minute they got their masks on and started their emergency descent in that same time period all just from memory reaction to the emergency at hand it wasn't till well later into the profile that they even began to bother with the cleanup items as we call them that's the items after the memory items of the engine severe damage failure checklist until probably 5 or 10 minutes from landing dare on the downwind base leg they were just running through some of those cleanup items they were busy doing job number one maintaining aircraft control and for that the crew got a fine pass for not going through every detailed step of all these checklists sometimes you think after going through a simulator sex session you think these checklists are written by lawyers they've cut so much detail in there some of it not really germane to the task at hand that you can see where it would distract you and take time away from the critical task of job number one maintaining aircraft control the other issue this crew was dealing with was communications it was just so loud in the cockpit with the explosive depressurization plus the complication of using the oxygen masks it made communication very difficult flight 1380 had 144 passengers on board they also happened to have 144 seats it was a completely full flight plus five crew members the two pilots and the three flight attendants when the window went out on seat 14 a that passenger was partially ejected out of that window but passengers flight attendants along with the help of the passengers were able to pull the passenger from seat 14 a back into the aircraft and begin resuscitation that meant that that entire row of seats of that aircraft were no longer usable one of them one of the big things we've learned in this incident is there's no guidance for this situation from the FAA or manufacturers what do you do in the event of a loss of in-flight seating during an emergency when this thing began to wrap up the jump seats were occupied by folks that were displaced from those those three seats of the row 14 seats though I think the forward jump seat was left empty and the flight attendants were left to sit on the floor of the aircraft as the aircraft landed and for this they were fairly well criticized because it's common knowledge and in the procedures that the flight attendants need to be in their jump seats for every landing especially an emergency landing because then they need to be able bodied enough to help with and in the event of an emergency evacuation sitting on the floor being restrained by passengers is not enough if the aircraft were to have a problem on landing back to the flight crew for a minute along with the engine failure severe damage hydraulic failure rapid or an explosive depressurization they've also got primary flight control difficulties they don't it's not clear to them what has happened to the aircraft and why are they having such difficulty in controlling the aircraft in fact the crew up front didn't know about the passenger situation in back and till within about five minutes of landing that's when they decided to abbreviate their approach into Philadelphia and get in there even faster and this is where experience comes into play the captain being a former fighter pilot knows that speed is life when you're learning to fly and fighter type aircraft sometimes you can you do a lot of formation flying and sometimes in formation flying you can run into each other fighter type aircraft have the luxury of an ejection seat but in the event that there is a some kind of a structural problem with your fighter type aircraft you can often if the aircraft is flying you can rejoin with your formation partner try to sort out what happened with the aircraft what the damage is but then you kind of got to do a flight profile to determine what the stalling speed of the aircraft is how are you going to land the aircraft at what configuration are you gonna land the aircraft the crew of Southwest Airlines 1380 obviously didn't have that that capability but from that training and experience the captain knew that speed is life faster is better I don't know what the stall speed of this aircraft is I don't know what's wrong with this aircraft I don't know why it's handling so bad well I've got I'll hold so much right aileron into this thing to keep it right and level I mean I know they know they knew something happened to the engine but to what extent they don't know and it's the aerodynamic drag of the cowling blowing out there plus all the damage to the leading edge of the wing that's causing all the problems and you don't know what's happened to your flaps and slats and the last thing you want to get is an asymmetric flap or slat situation while configuring for landing so the crew upfront debates back and forth what to do typically on a single-engine landing you call four flaps fifteen into a flaps fifteen landing as opposed to full flaps so that you have reserve energy in the event of a go-around single-engine go around going around on one engine that you've got enough power to do that and enough aerodynamic capability or not so much drag to to prevent that from happening so they debated back and forth whether it's going to be a flaps 15 landing or not and in the end the captain decided to go with flaps 5 I've landing and landed at a very high rate of speed I think something about him 180 190 miles an hour in order to maintain speed speed his life if you go through the cockpit voice recorder transcript you'll hear on the approach to landing you'll hear a lot of low altitude warnings and a lot of glideslope warnings well that's planned they're coming in fast and hot and low and flat and so they're flying below the glide path and close to the terrain setting off the train warnings in order to achieve a high speed landing the trick is you got to land you still got to land the aircraft in the zone and that's where Navy carrier training comes in the captain was able to easily get it in the zone on the end of the runway which is tricky to do at that very high rate of speed and not blow past the landing zone and jeopardize rolling out or landing too long on the runway now let's talk a little bit about the main inside of this engine and fan blade in particular this cfm56 - 7b engine was manufactured in 2000 along with the blades as well and installed in 2001 into the airframe this particular engine and fan blade section had 32,000 630 cycles the fan blade section I assume the entire engine was overhauled in 2004 and again in September of 2012 during those two overhauls the protocol at the time was for a fluorescent penetrant inspection or what we call dye penetrant and inspection where you squirt the penetrate on there and then you've got a solution that that mixes in with it that will bring out any hard-to-see or impossible to see visual cracks the blades never indicated any cracks during those two overhauls yet the size of the failure of this crack indicates to investigators that this crack had began nearly 20,000 cycles ago this crack was there while that blade was overhaul the fluorescent penetrate inspection didn't catch it why in part because the coat the dovetail section of the fan blade is coated with a hardened coating and that can mask cracks underneath that hardened coating so as a result of the first fan blade partial fan blade out event where the aircraft diverted into Pensacola CFM manufacturers FAA everybody got together and began revising the inspection protocol and procedures and began introducing ultrasound testing same thing you use during pregnancy and eddy current testing here's how each of the 24 titanium alloy blades slide into the fan disc near the contact face section of the dovetail is hardened often masking or making it difficult to find cracks below the hardened surface these fan blades also require periodic lubrication and at Southwest Airlines it appears that they remove these fan blades about every fifteen hundred cycles the lubrication involves also a visual inspection of the fan blades why do you got to lubricate the fan blades when you when you the engines are spinning when the winds blown through the engine maybe after you D playing off of the aircraft you can hear the fan blade section rotating and you hear it clattering away those fan blades need to fit in the dovetail section with a little bit of looseness to them and that looseness needs to be there so that when you apply power to the fan blades section it seats in its proper location and reduces n1 vibration of the engine so you keep them lubricated basically to minimize vibration and if any of you cfm56 technicians are out there watching this please leave it in the comment section below any more information that you can give us about the lubrication of these fan blades so there's several different types of overhauls there's on wing inspection and an off wing or different levels of shop maintenance facilities of overhaul and on winning an on wing inspection where technicians can pull the blades off while the engines still on the airplane at that point through all these series of service bulletins and airworthiness directives folks are now checking these blades are required to check them every fifteen to sixteen hundred cycles if you do an on wing inspection as I understand it you're required to do an ultrasound inspection if you do an off wing inspection at 1600 cycles you're required to do an eddy current inspection remember an 80 current you can run a magnetic field over a metal object and if there's a crack in that metal object it disrupts the fields and it'll show up on the on the test manufacturers have developed special tools to get these tests done on these fan blade dovetail sections what about the passenger oxygen we've all seen the picture on the in the media there where the passengers are improperly wearing their masks again we don't know if that they were below 10,000 feet they were beginning to take their masks off or they simply didn't pay attention to the briefing but nevertheless that's one of the many outcomes of this is pay attention to the flight attendant briefings remember to when we're talking about oxygen passenger oxygen passenger emergency oxygen you need to jerk to begin the flow of oxygen you've got a jerk on the I want to call Dixie club or the line lightly enough to fire off the trigger to set off the chemical reaction and the little chemical canisters that are located in the overhead bin to begin the flow of oxygen and your baguette may or may not fill up just depends on your breathing at the time the thing we've found out with this incident is you don't want a jerk too hard or you'll pull the line right off the end of the emergency oxygen canister and flight attendants we're having to take some time going around the cabin and reattaching folks is lying back to the emergency cannister so they the passengers had their emergency walk-around oxygen bottles which they can carry with them and then they would find a passenger that was having problems with their emergency oxygen the flight attendant mask share it with the passenger while they reattached the line back to the emergency cannister so so when you jerk to inflate or begin the flow of oxygen don't you think it too hard but that's going to be a challenge and something is terrifying is this so amongst many findings how come this cowling reacted so much differently than the certification testing as required by the FAA well they got into depth in the discussion about test rigs and how these aircraft are certified when they're certified they're certified using test rigs that is maybe a portion of the assembly not the complete assembly is tested they'll take a portion of the engine that they want to test for a fan blade out operation and just ensure that the fan case does its job and contains the fan blade out if they don't necessarily have the entire engine there maybe they don't even have the entire inlet and cowling on the engine when they do these tests and maybe they don't even test it well I'm not sure how much they test each clock position of the fan blade according to one investigator he did say that they they checked it about every 30 minutes of rotation from the 12 back to the 12 o'clock position to see to see how the cowling would react but I'm not sure how you'd get the data on that other than through structural analysis once they get some solid data points then they can go into computer modelling and see how the cowlings going to react nevertheless these cowlings failed catastrophically and they're one of the findings and one of the directives is to basically redesign or beef up or change slightly the design of the 737ng cowling series and they want to first start with new 737 maxes cowlings and apply what they've learned from this incident and then go back and retrofit cowlings for previous already built versions of the 737ng and of course the other findings are the increased or stepped-up inspection of the fan blades themselves out of the stepped-up inspections that they've done since these two incidents they found only a total of 23 blades with cracks out of the hundreds of thousands of blades that are out there in service so again a very tiny remote chance of this happening it happened twice and the other safety recommendation from the NTSB to forward to the FAA is to do some research on what do we do in the event of loss of seating in an emergency situation that's something we've never really considered before now that flights are so darn full we need additional guiding for flight crews flight of tents as to what to do in the event that you have lost seating capability of seating all of your passengers while in flight one thing we've got to remember is the role of the FAA and the NTSB remember the FAA has a dual mandate of enforcing the rules in aviation they also have a dual role of promoting aviation as well that's why when you see recommendations for changes through normal airworthiness directives the FAA is required to do a cost analysis and make sure that the cost well that they factor in the cost of the requirement that they're about to impose in the case of an emergency air worthiness directive that's not the case it's just get er done and that's where the role of the NTSB steps in the NTSB was created some years ago to be a bit of an oversight to the EMT SB to the FAA however the NTSB cannot does not make regulations the NTSB can only make recommendations to the FAA and it's up to the FAA to carry out the recommendations of the NTSB so from this incident we've learned more about how these aircraft are certified we've learned more about the testing and inspecting of fan blades particularly in the cfm56 series of aircraft they're bolstering those inspections we've also learned about passenger reactions in the event of explosive depressurization and the loss of seating in an emergency plus the use of checklists in the event of an emergency versus the need to maintain aircraft control and land as soon as conditions permit so lots of important information is coming out of this investigation this is how we learn in aviation this will be passed on and we can continue to maintain our excellent aviation safety record here in the United States see you here [Music] [Music] you [Music]
I've been wondering what happened with this flight! Thanks for posting!
Also found this CVR https://youtu.be/FkVTdvcghHc