The Latest: Fire chief: 1 critical after emergency landing

[Gerald]

A Southwest Airlines flight was diverted to Philadelphia after a plane sustained damage on Tuesday, April 17. The flight had left La Guardia Airport in New York and was headed to Dallas before it experienced problems. Passenger Marty Martinez was traveling from New York City to Dallas, Texas, when the incident occurred.

https://www.sfgate.com/news/texas/ar...n-12841164.php

They were lucky.

[GoldenRivet]

interesting. not the first failure of its type.

[Gerald]

Has it happened many times.

[Jimbuna]

Originally Posted by GoldenRivet

interesting. not the first failure of its type.

True that, a similar incident was recorded in 2016 involving a Southwest flight that landed safely in Florida.

http://www.bbc.co.uk/news/world-us-canada-43818752

[GoldenRivet]

Originally Posted by Vendor

Has it happened many times.

only a couple of instances come to mind, but i believe the first occasion was the result of the failure of a Fan blade and this one is likely to be the same cause.

here is video of a test showing what occurs when a fan blade fails:

the most impressive footage begins around 1:20

as you can see, a single fan blade detachment can cause a chain reaction which damages and separates additional fan blades, and ultimately causes the engine to ingest thousands of bits of jagged metal which further damages turbine components, compressor blades etc

Fan blade failure is probably the most dangerous and catastrophic type of engine failure one can experience in a turbofan engine.

One of the immediate dangers in such an event is that of debris and shrapnel. Yet, there are design elements in place meant to contain the failure and prevent such debris from fragmenting into more critical areas like fuel systems, hydraulic systems, or worse... the passenger cabin. (as was the case with Southwest Airlines recent experience.)

In the 2016 case, the failure occurred in such a way so as to carry debris either up and away from the cabin, or down and away from the cabin. This was sheer luck alone.

this most recent event, unfortunately saw the failure occurring in such a way as to carry the debris into the fuselage and main cabin, and it cost a woman her life.

Preliminary indications are that a hairline crack, not immediately visible to the naked eye, caused the blade to fail. Fan blades are subjected to enormous physical stress during their normal operations. It is not clear whether the stress of normal wear and tear caused the hairline fracture, or if it was a case of manufacturer defect.

another question investigators are surely looking at is - why was the failure in either case of these engines not contained?

it would be impossible to contain 100% of such failures unless the engine cowl itself were made of thick plate steel armor but that would be like going after a house fly with a sub-nuclear bomb. So some fan blade failures will cause this sort of destructive damage, but most will not. and on the whole, it is a fairly rare occurrence. but odd that it would happen to two engines of the same type, on two aircraft of the same type within such a short span of time.

EDIT:

reference the Sioux City crash of United flight 232- shrapnel from a catastrophic fan blade failure knocked out the hydraulic system of the entire aircraft leaving the flight control system inoperable. The skill of the crew alone was the only thing that achieved the outcome of that flight and the fact that there were not 100% fatalities is testament to their capability. The outcome of the flight is also testament however to the potential severity of such a fan blade failure

[Mr Quatro]

Originally Posted by Jimbuna

True that, a similar incident was recorded in 2016 involving a Southwest flight that landed safely in Florida.

http://www.bbc.co.uk/news/world-us-canada-43818752

Southwest airlines has a strange take off policy that i have witnessed. They take off in a hurry and then head straight up at a larger angle than the other airlines that take off before and after they do.

I wonder if this could add to more stress on the engines after a lot of these tak off's?

Did you notice that a man used his own body to block the window on that jet till it was safely lower in attitude?

[GoldenRivet]

Originally Posted by Mr Quatro

Southwest airlines has a strange take off policy that i have witnessed. They take off in a hurry and then head straight up at a larger angle than the other airlines that take off before and after they do.

this is sometimes required by noise abatement or obstacle clearance procedures in effect for specific airports. What makes southwest standout is that they operate one single fleet type, where other airlines operate a variety of fleet types. So, you may see what appears to be exaggerated climb performance from a 737-400 when compared to that of say, an MD-80 or a 747 or even a Cessna 172 performing the exact same noise abatement procedure because climb performance will be significantly different between models.

Originally Posted by Mr Quatro

I wonder if this could add to more stress on the engines after a lot of these tak off's?

not likely. The engine parameters used in the calculation of takeoff power are dictated by the manufacturer and account for weight and atmospheric conditions. For example, given the "known data" of aircraft weight, atmospheric pressure, humidity, density and temperature, the manufacturer's data would provide a given N1 Power setting to be used for takeoff and can be computed manually or electronically. Lets assume the manufacturer's data said to use an N1 Speed of 92% for takeoff given the current atmospheric and weight conditions; that would be the N1 speed used, and by all available information provided by the company that built the engine, it would be within the capabilities of the engine to handle it.

climbing more steeply (or conversely - adopting a more shallow climb) would not change the N1 speed by any measurable amount (if at all). Only the indicated airspeed and rate of climb resultant from the available amount of power would be affected, and these shouldn't have any bearing on the structural integrity of the engine components.

given that you have this type of fan blade failure in two CFM-56 type engines would normally point to a manufacturer defect.

however, the CFM-56 is in use aboard a number of different air-frames with both civil and military operators.

given that both failures occurred with the same airline would be an indication that either the in house maintenance is the origin of the issue, or some flight procedure specific to southwest is the origin of the issue. So your takeoff theory is not very far off base. but "flight procedures" can encompass everything from startup to shut down and all phases of the flight in between.

An error in manufacturing could impact the entire CFM-56 type, or only a specific run produced during a specific time range. (of which southwest may be the sole purchaser for a specific run)

the other end of the investigation needs to answer the question - what is Southwest doing to its CFM-56 engines, that numerous other operators are not?