Loss of engine cover on Southwest Boeing 737-800 prompts FAA investigation

[tdracer]

Originally Posted by Junkflyer

Flaps and slats work off the same lever. Can't speak for the 737, but typically slats are first or in conjunction with some flaps.

If memory serves, the LE device deploys as soon as you go flaps 1 - so there is not a flap setting that wouldn't have deployed the (potentially damaged) leading edge.
There is probably some technique of pulling circuit breakers or the like to prevent LE deployment, but I doubt that would be in the checklist.

[xetroV]

Originally Posted by waito

Another note: the LE device, slat next to the engine seem to show sort of puncture. Reason enough to avoid using flaps. Possible assymetry in slats is quite uncomfortable. As would TE setting without LE, but I think this is prevented.

During the roll-out the engine cover punctured a slat (it appears at 7:50 in the video I posted earlier in post #30); the puncture did not seem to be present during flight. Which makes me wonder whether the crew visually inspected the damaged engine cowling themselves before deciding to do a flaps-up landing. Also note that they told ATC they had "structural damage", which suggests that they believed the damage was more substantial than 'just' a loose engine cowling.

I'm not criticizing their decision-making, by the way; after all they did have a very long runway readily available for an immediate overweight flaps-up landing. And I can totally understand why they wanted to land ASAP, considering the possibility of debris from the engine hitting the wing (or even the horizontal stabilizer).

[waito]

Originally Posted by tdracer

If memory serves, the LE device deploys as soon as you go flaps 1 - so there is not a flap setting that wouldn't have deployed the (potentially damaged) leading edge.
There is probably some technique of pulling circuit breakers or the like to prevent LE deployment, but I doubt that would be in the checklist.

Correct in normal conditions
Flaps 1-5 drives the 8 LE slats in intermediate extended, and 2 LE flaps into full extended pos as soon as lever leaves flaps up setting.

[Junkflyer]

Originally Posted by tdracer

If memory serves, the LE device deploys as soon as you go flaps 1 - so there is not a flap setting that wouldn't have deployed the (potentially damaged) leading edge.
There is probably some technique of pulling circuit breakers or the like to prevent LE deployment, but I doubt that would be in the checklist.

I remember the story of a captain on the 727 who used to pull a c/b for L/E devices and put a slight bit of flaps in to increase speed in cruise. As legend goes, one of the other crewmembers came back into the cockpit and noticed the c/b out so pushed it in. The leading edges came out but one tore off or something and sent the aircraft into a roll and the aircraft lost thousands of feet in altitude before recovering.

[waito]

Originally Posted by xetroV

... the puncture did not seem to be present during flight.

Well, look at the picture in post 15. puncture is visible, and it appears to be in flight.

[MartinB738]

Originally Posted by Jonty

Not 30 times, I can name about 3 times it happened.
Thing is, it’s a known issue to the point it prompted a design change from Airbus. Why didn’t Boeing take note and change their design?

What was the design change? I recall talk of a spreader to force the cowls apart if unlatched, and a warning light? Thanks in anticipation.

[slacktide]

Originally Posted by Junkflyer

I remember the story of a captain on the 727 who used to pull a c/b for L/E devices and put a slight bit of flaps in to increase speed in cruise.

Wow, I bet that was a real Hoot.

[Loose rivets]

It probably went supersonic and caused the right landing gear to be pushed back into the wing structure. The decent was probably the most dramatic for a non fatal accident in the history of aviation.

[TURIN]

Originally Posted by MartinB738

What was the design change? I recall talk of a spreader to force the cowls apart if unlatched, and a warning light? Thanks in anticipation.

A key was introduced on the CEO fleets. The key is kept in the flt deck with the landing gear ground locks. To open the cowling the key is inserted under the engine and cannot be removed until the cowlings are latched closed again. The key has a long 'remove before flight' flag attached.
On the NEO fleet there is a spring that pushes the cowlings apart, there is also a mechanical flag that pops out of the side of the cowling if the (no.2?) latch isn't locked and there's also a flt deck ECAM warning if the cowlings are not fully latched.
Maybe it's time Boeing did something similar.

[FullWings]

Originally Posted by Last200ft

Definitely not an easy one, well done by the crew. Just a thought re flap up landing… In theory, even if the slats are damaged, there should still be some sort of asymmetry protection. Would it be worth trying in this kind of scenario? Technically if something goes wrong you can bring them back. Or maybe the system design would stop the slats and let you use the flaps at least? Again, those are just thoughts for myself, kudos to the crew and ATC

With a non-normal, once you have got the aeroplane into a configuration which is safe for flying and landing (but maybe unusual) conventional wisdom says stop “troubleshooting” and get on with it. Attempting something novel to make things “better” at that point has a limited upside and a potentially unlimited downside. Especially if you don’t have intimate knowledge of what exactly is wrong...

[Yancey Slide]

Originally Posted by Junkflyer

I remember the story of a captain on the 727 who used to pull a c/b for L/E devices and put a slight bit of flaps in to increase speed in cruise. As legend goes, one of the other crewmembers came back into the cockpit and noticed the c/b out so pushed it in. The leading edges came out but one tore off or something and sent the aircraft into a roll and the aircraft lost thousands of feet in altitude before recovering.

TWA 841

[OldnGrounded]

Originally Posted by Yancey Slide

TWA 841

It's a helluva story.

Gibson shouted, "We're going over!". Flight 841 dove about 34,000 feet (10,000 m) in just 63 seconds.[3]: 2  During the course of the dive, the plane rolled through 360 degrees twice and exceeded the Mach limit for the 727 airframe.

https://en.wikipedia.org/wiki/TWA_Flight_841_(1979)

https://www.ntsb.gov/investigations/...ts/AAR8108.pdf

[Sailvi767]

Originally Posted by Jonty

Not 30 times, I can name about 3 times it happened.
Thing is, it’s a known issue to the point it prompted a design change from Airbus. Why didn’t Boeing take note and change their design?

Because the design is fine. You just need to latch it. Southwest Airlines until recently did not require pilot walk arounds relying on rampers to do the preflight. Not sure in this case if a pilot was required to walk around.

[Peter Fanelli]

Originally Posted by pattern_is_full

Really? Where?

SWA does not operate any aircraft type except 737 variants (to maintain system-wide crew compatability).

https://en.wikipedia.org/wiki/Southwest_Airlines_fleet

https://registry.faa.gov/AircraftInq...umberTxt=8668A

You must be the life of every party.
It was a sarcastic remark.

[waito]

NTSB stopped investigating this event.
Maintenace haopened the night before, and NTSB is satisfied with declaring it a maintenance issue and the airline addressing it.

See avherald, where I picked this up.

[BFSGrad]

N8668A patched up enough to fly. Currently enroute from DEN to PAE. Since SWA doesn’t serve PAE, assume positioning is for additional maintenance at Boeing.