TACA flight 110- fascinating video for a Sunday morning

GON

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Outstanding video, a little over 30 minutes. Enjoy your Sunday morning coffee and this video.

"A one eyed pilot that outflies most of his peers! GREAT story, fantastic airmanship !!! Wish I could shake his hand!"
(one of the comments on the video)
 
"The National Transportation Safety Board determines the probable cause(s) of this incident as follows.

"A DOUBLE ENGINE FLAMEOUT DUE TO WATER INGESTION WHICH OCCURRED AS A RESULT OF AN INFLIGHT ENCOUNTER WITH AN AREA OF VERY HEAVY RAIN AND HAIL. A CONTRIBUTING CAUSE OF THE INCIDENT WAS THE INADEQUATE DESIGN OF THE ENGINES AND THE FAA WATER INGESTION CERTIFICATION STANDARDS WHICH DID NOT REFLECT THE WATERFALL RATES THAT CAN BE EXPECTED IN MODERATE OR HIGHER INTENSITY THUNDERSTORMS."


This B737 finished its career with Southwest Airlines IIRC years later.

You have to be very careful flying around thunderstorms even with weather radar. Its meant for avoiding the weather ( which they thought they were doing ) but heavy rain can deceive pilots into thinking its safe to go in a certain weather deviation heading when its not ( newer radars are better ).

Reminds me of Garuda flight 421 ( also flamed out and crash landed after flying into severe weather when they thought it was safe to fly between two big cells on the radar ). Both are lucky it happened during daylight or it could have been a total disaster.


Garuda flight 421:

 
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You have to be very careful flying around thunderstorms even with weather radar. Its meant for avoiding the weather ( which they thought they were doing ) but heavy rain can deceive pilots into thinking its safe to go in a certain weather deviation heading when its not ( newer radars are better ).
Dumb question. Why can't you fly over the rain clouds or is this too dangerous or are they too high?
 
The only type of weather you should try to avoid flying over are thunderstorms. Commercial passenger jets can’t get high enough ( max altitude limit ) to go above the big ones anyways but if we can, it’s not recommended to fly above them unless +5000 above the top or 10,000 above if the upper winds exceed 100 knots. Dangerous updrafts can occur and cause jet upset, loss of control.

Some radars show the wet top while others don’t so you don’t know what the tops are if in cloud.

We can, and do , fly through rain/heavy rain but you have to be careful when deviating around heavy rain from thunderstorms because the radar signal might not be able to penetrate heavy rain when flying between cells and risk flying into severe weather thinking it was safe because the radar was not able to detect the threat ahead.
 
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I thought all jet engines went thru water ingestion tests prior to certification. :unsure:

The video showed that hail was not part of the water injeston test. It was the hail that caused the engines to flame out, not water. The engine manufacturer made revisions so the engines could stay running when hail is injected because of this incident.
 
I thought all jet engines went thru water ingestion tests prior to certification. :unsure:

Thanks to that TACA incident, the FAA insisted Jet engines could survive a flameout with much higher amounts of water being sucked in IIRC ( they definitely changed the design of that particular engine involved after ). I will check later about that.

That said, hail can cause airflow disruptions due to blade damage and you can still have an engine stall.
 
I thought all jet engines went thru water ingestion tests prior to certification. :unsure:

That is good, but nowhere near as much water as exists in a heavy downpour associated with a thunderstorm.

We go around thunderstorms. Period.

Anyone who doesn’t is a fool.

Thunderstorms often top 50,000 feet, well above the altitude capability of commercial aircraft, further, they often have hail and severe turbulence several thousand feet above the apparent “top” of the storm. Going over them is foolish.

But the downpour/radar return in the cell nearest the airplane can be so heavy that it blocks the return of weather behind the initial cell. A “radar shadow” is a trap, into which many have flown, because it looks like the weather is clear on the other side, when it is, actually, worse.

 
This is what caused the engines to flame out:

The NTSB determined that the aircraft inadvertently flew into a level four thunderstorm and that water ingestion caused both engines to flame out during descent.

The end of the report talks about the CFM56 engine and hail assumptions but the report also talks about the FAA water ingestion certification standards underestimating just how much water can be encountered in some thunderstorms.


NTSB findings are in this report:


Technical Related Lessons:​

Turbine engines must be capable of operation in a wide range of atmospheric conditions, including severe hail and rain. (Threat Category: Inclement Weather/Icing)

  • All-engine flameout events due to environmental threats and other causes may occur at a very low probability during the life of the fleet. Engine design standards for an environmental threat, such as hail, are driven in part by the probability of encountering a hailstorm of a certain severity. This approach recognizes that there are hailstorms of greater severity that may be encountered (at a very low probability) during the life of the fleet, and that these storms must be avoided.
Flight crew training should include information regarding the performance and inherent limitations of onboard weather radar systems. (Threat Category: Inclement Weather/Icing)

  • In this event, a contributing factor was the weather radar display, which appeared to show a path through the severe weather. In fact, the seemingly clear path was the result of the radar's inherent inability to depict weather beyond its saturation limits (beyond "red"). Since this event, information has been distributed to flight crews, and training programs initiated, aimed at providing information on the limitations of weather radar systems and how severe weather may be depicted.

Common Theme Related Lessons:​

Past assumptions must be confirmed as relevant to present designs. It is necessary to understand the origins of original assumptions before they can continue to be considered valid. (Common Theme Category: Flawed Assumptions)

  • An underlying assumption made in the CFM56 design was that the hail threat was considered adequately addressed by accommodating the threat posed by heavy rain concentrations. Extensive testing following this event discovered that hail behaved very differently than water when entering the inlet. As such, specific design changes would be necessary to be made to the CFM-56 engine in order the improve the engine's ability to continue operating in certain high concentrations of hail.
 
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Missed it first read of the report but here is says both, heavy rain and hail caused it to flame out.

  • Severe hail and rain encounter led to a dual-engine flame out. The CFM56 engine proved to be vulnerable to high concentrations of hail.
Edit: typo ( I can spell believe it or not ). 🙂
 
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Jet engines can handle rain, and even if the fire is snuffed out, will relight pretty quickly.

But hail? Those balls of ice can both snuff out the flame, and bend blades. Once the internal parts of a turbine start taking mechanical damage, all bets are off for a relight, or any sort of thrust production...
 
Ice slab, hailstone, heavy rain, and bird ingestion testing.

GE said they put 1 ton of manufactured hail through the engine I read elsewhere.


Edit:

“In Jet engines air is compressed by fan blades and directed to the combustion chamber, where it is mixed with fuel and ignited. The hot exhaust gases then exit the engine and provide thrust. A jet engine can handle a large amount of water ingestion, as most of the water is spun out by the fan blades and flows through the bypass duct, which is the space between the engine core and the cowling.

Jet engines don’t have any flame in the primary airflow path. Air first passes through a compressor, then some of the compressed air is diverted into one or more combustors, insulated cans in which fuel and compressed air are mixed, burned, then mixed with the rest of the already compressed air. The resulting hot mixture then drives a turbine to power the engine.

In order for rain to kill the engine, enough water would have to enter the core and reach the inside of the combustors in enough quantity to cool them below the ignition temperature of the fuel air mixture. This is prevented by simply making the air entering the combustors make a sharp turn that the denser water cannot make (and depending on the engine, using similar tricks at other key locations).

The bypass air does not enter the combustion chamber, but rather provides additional thrust and cooling for the engine core. Therefore, only a small fraction of the water actually reaches the combustion chamber, where it is quickly vaporized by the high temperature.

main-qimg-fc5e80488eb347b6468c52030f648372

The combustion chamber of a jet engine can reach temperatures of up to 900 °C (1,650 °F), which is much higher than the boiling point of water. So any water that enters the combustion chamber is instantly converted into steam, which does not affect the combustion process significantly. The pressure in the combustion chamber is also very high, which prevents water from condensing or freezing on the engine components.

Jet engines have to meet certain standards and regulations for water ingestion, which are based on extensive testing and simulation. They are exposed to artificial rain and ice during the certification process, and they have to demonstrate that they can operate safely and reliably under these conditions. These engines also have features that prevent or minimize the effects of water ingestion, such as heated intakes, anti-icing systems, water separators, and drain valves. These features help to prevent ice formation, water accumulation, and corrosion in the engine.”
 
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Ice slab, hailstone, heavy rain, and bird ingestion testing.

GE said they put 1 ton of manufactured hail through the engine I read elsewhere.


Edit:

“In Jet engines air is compressed by fan blades and directed to the combustion chamber, where it is mixed with fuel and ignited. The hot exhaust gases then exit the engine and provide thrust. A jet engine can handle a large amount of water ingestion, as most of the water is spun out by the fan blades and flows through the bypass duct, which is the space between the engine core and the cowling.

Jet engines don’t have any flame in the primary airflow path. Air first passes through a compressor, then some of the compressed air is diverted into one or more combustors, insulated cans in which fuel and compressed air are mixed, burned, then mixed with the rest of the already compressed air. The resulting hot mixture then drives a turbine to power the engine.

In order for rain to kill the engine, enough water would have to enter the core and reach the inside of the combustors in enough quantity to cool them below the ignition temperature of the fuel air mixture. This is prevented by simply making the air entering the combustors make a sharp turn that the denser water cannot make (and depending on the engine, using similar tricks at other key locations).

The bypass air does not enter the combustion chamber, but rather provides additional thrust and cooling for the engine core. Therefore, only a small fraction of the water actually reaches the combustion chamber, where it is quickly vaporized by the high temperature.

main-qimg-fc5e80488eb347b6468c52030f648372

The combustion chamber of a jet engine can reach temperatures of up to 900 °C (1,650 °F), which is much higher than the boiling point of water. So any water that enters the combustion chamber is instantly converted into steam, which does not affect the combustion process significantly. The pressure in the combustion chamber is also very high, which prevents water from condensing or freezing on the engine components.

Jet engines have to meet certain standards and regulations for water ingestion, which are based on extensive testing and simulation. They are exposed to artificial rain and ice during the certification process, and they have to demonstrate that they can operate safely and reliably under these conditions. These engines also have features that prevent or minimize the effects of water ingestion, such as heated intakes, anti-icing systems, water separators, and drain valves. These features help to prevent ice formation, water accumulation, and corrosion in the engine.”
That is a great description, and a great explanation. I admit that I was over-simplifying to contrast the difference between rain and hail.

On the latest engines, the bypass can be as high as eight to one. That is, eight parts of air going around the outside, while only one part goes through the core.

Airplanes I have flown are lower than that. I have been through some heavy rain, and have yet to flame one out. Managed to flame a few out doing other stuff, but it’s not really germane to the airliner discussion.
 
That is a great description, and a great explanation. I admit that I was over-simplifying to contrast the difference between rain and hail.

On the latest engines, the bypass can be as high as eight to one. That is, eight parts of air going around the outside, while only one part goes through the core.

Airplanes I have flown are lower than that. I have been through some heavy rain, and have yet to flame one out. Managed to flame a few out doing other stuff, but it’s not really germane to the airliner discussion.
To be honest, until I read that article and did some extra research yesterday, I didn’t fully understand how jet engines could handle so much water except that they could due to having to meet strict standards.

You also just explained things well by saying just how much water misses the core on these ultra high bypass engines.
 
To be honest, until I read that article and did some extra research yesterday, I didn’t fully understand how jet engines could handle so much water except that they could due to having to meet strict standards.

You also just explained things well by saying just how much water misses the core on these ultra high bypass engines.

I remember a discussion of jet engine materials in a lower division materials science class. I thought the prof said that they tossed a frozen chicken or turkey in testing. I was thinking an engine was supposed to be able to withstand that, but he might have said it was to see if the aftermath can be contained, even if the engine fails. And he might not have said frozen either. This is one of those things where I’m sure I’ve changed parts of the story.
 
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