I live near the KSAN approach and it seems like nearly half the time, I’ll see 737 equipped with SS winglets missing the “dorsal” structure on one wing. Would this incur any fuel penalty? Anyone have insight on why this seems to be a very common occurance?

Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.

Oops, I totally mixed up my terminology: it was the ventral fin... Thoughts?

B6JFKH81 wrote:

Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.

I think your thinking that their made like MAX style winglets as one piece. The Split Scimitar winglets are normal Blended winglets with a new cap on top and anchor points added to the side to mount the lower section (and associated reinforcement).

Looking at these photos they are indeed a 2 piece assembly
https://www.google.com/search?q=split+s ... =943&dpr=1

Raventech wrote:

B6JFKH81 wrote:

Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.

I think your thinking that their made like MAX style winglets as one piece. The Split Scimitar winglets are normal Blended winglets with a new cap on top and anchor points added to the side to mount the lower section (and associated reinforcement).

Looking at these photos they are indeed a 2 piece assembly
https://www.google.com/search?q=split+s ... =943&dpr=1

....and if you look at the pictures you reference, the dorsal fin is the primary structure and the ventral fin is attached to it. So, you can’t have a dorsal fin missing without the entire assembly missing.

As per the OP, he was discussing the ventral fin actually what was being asked about, and in that case I really don’t know what the MMEL or SDL calls out for on the 737. I was not talking about the MAX wingtip device as that seems to be a single part.

The terminology used in the patents is "upward wing-like element" and "downward wing-like element." Which is wordy, I know.

Anyway, the upward WLE cannot be MELed because the nav lights are integrated into the structure. I believe the downward WLE can be MELed but flying with only one comes at a small penalty because in addition to the overall loss of lift, there will be an asymmetrical lift on the aircraft and the ailerons (and hence the rudder) will have to compensate.

"downward wing-like element."

Anyway, the upward WLE cannot be MELed because the nav lights are integrated into the structure. I believe the downward WLE can be MELed but flying with only one comes at a small penalty because in addition to the overall loss of lift, there will be an asymmetrical lift on the aircraft and the ailerons (and hence the rudder) will have to compensate.

Can anyone shine light on, or speculate, why this element is so commonly missing said element? From my eye, like 40% of the many so equippedAre they more prone to damage requiring maintenance more frequently than other parts? It would suggest poor engineering to me.

You can CDL the ventral strake. If you remove one, you have to remove the other so you don't have asymmetry. There is no performance penalty at my airline due to the fact that we consider both SSW and Blended winglet the same.

The reason they are removed so frequently is due to the fact that they disappear at night when driving up behind them. You really can't see them, and if an operation doesn't have good ramp practices, trucks try to go under the wing and boom it's ripped off.

rjsampson wrote:

"downward wing-like element."

Anyway, the upward WLE cannot be MELed because the nav lights are integrated into the structure. I believe the downward WLE can be MELed but flying with only one comes at a small penalty because in addition to the overall loss of lift, there will be an asymmetrical lift on the aircraft and the ailerons (and hence the rudder) will have to compensate.

Can anyone shine light on, or speculate, why this element is so commonly missing said element? From my eye, like 40% of the many so equippedAre they more prone to damage requiring maintenance more frequently than other parts? It would suggest poor engineering to me.

The fact that the downward WLE projects downward makes it an easy thing for ground vehicles to hit.

flybaurlax wrote:

You can CDL the ventral strake. If you remove one, you have to remove the other so you don't have asymmetry. There is no performance penalty at my airline due to the fact that we consider both SSW and Blended winglet the same.

In reality, there is a performance penalty of a couple of percent. Your company may choose to ignore it because it doesn't affect handling like the upward WLE does (it increases rotation rate and crews need to be prepared to avoid tail strikes) and it makes it simpler from an operational perspective. I swear I've seen some A/C flying with only one attached. Maybe I was imagining it?

It's puzzling to me that in such a procedure-conscious and safety-conscious industry that nobody has figured out how to keep people from driving into the downward WLE.

flybaurlax wrote:

The reason they are removed so frequently is due to the fact that they disappear at night when driving up behind them. You really can't see them, and if an operation doesn't have good ramp practices, trucks try to go under the wing and boom it's ripped off.

That is why our airline's ground handling practice is to cone them (one at the tip of each wing, one in front of each engine, and one at the tail).

rjsampson wrote:

Oops, I totally mixed up my terminology: it was the ventral fin... Thoughts?

Im assuming you mean the lower, smaller (vertical fin) part of the scimitar. If that part of the winglet is damaged, it can be removed per the CDL, however the other winglet ( vertical fin) must also be removed. Exactly what happened today on a DL 739 today.

DL777200LR wrote:

rjsampson wrote:

Oops, I totally mixed up my terminology: it was the ventral fin... Thoughts?

Im assuming you mean the lower, smaller (vertical fin) part of the scimitar. If that part of the winglet is damaged, it can be removed per the CDL, however the other winglet ( vertical fin) must also be removed. Exactly what happened today on a DL 739 today.

Out of curiosity, is the damage typically limited to the lower fin itself, or do inspections need to be performed at the connecting point of the fins, and the upper fin itself, for stress cracks and whatnot? How long does it take to remove the lower fins? What is used to cover that connection point while on CDL, speed tape?

Sorry so many questions, just not familiar with the SS wingtip devices at all!!

B6JFKH81 wrote:

DL777200LR wrote:

rjsampson wrote:

Oops, I totally mixed up my terminology: it was the ventral fin... Thoughts?

Im assuming you mean the lower, smaller (vertical fin) part of the scimitar. If that part of the winglet is damaged, it can be removed per the CDL, however the other winglet ( vertical fin) must also be removed. Exactly what happened today on a DL 739 today.

Out of curiosity, is the damage typically limited to the lower fin itself, or do inspections need to be performed at the connecting point of the fins, and the upper fin itself, for stress cracks and whatnot? How long does it take to remove the lower fins? What is used to cover that connection point while on CDL, speed tape?

Sorry so many questions, just not familiar with the SS wingtip devices at all!!

No inspections required since it wasn’t a major damage just a dent from ground contact. I believe it’s held on by 8 bolts and I don’t believe there was a speed tape necessary.

Where are you seeing these planes missing the lower part? If they're flying overhead and you're looking at them from below/at an angle, I'd almost guarantee that it's an optical illusion due to lighting. There's no way that 40% of split-scimitar 737s are missing a piece of the winglet.

I've seen plenty of split-scimitar 737s overhead where I swear they were missing the lower strake, but when I eventually got a good enough view at a different angle, I could then see them quite clearly.

hOMSaR wrote:

Where are you seeing these planes missing the lower part? If they're flying overhead and you're looking at them from below/at an angle, I'd almost guarantee that it's an optical illusion due to lighting. There's no way that 40% of split-scimitar 737s are missing a piece of the winglet.

I've seen plenty of split-scimitar 737s overhead where I swear they were missing the lower strake, but when I eventually got a good enough view at a different angle, I could then see them quite clearly.

On approach to 27 in San Diego. I too had thought that may be the case the first couple of times, after watching countless approaches, I am 100% certain I've seen several aircraft single ventral strake removed on many aircraft, on one wing only. I have a pretty good sample size, too. I take my dog to a park in Balboa Park, which has outstanding views of approaching aircraft. Not directly under the approach. And of course, being the AvGeek I am, I almost always at least glance at the approaching aircraft.

Additionally, I've seen the approach from many different locations and consistently observe the same thing. Now, 40% may be a subconscious exaggeration given that they really stick out, but it's not an inconsiderable number. Maybe one of the SW drivers here or MX would have insight?

It is not very common. Lots of people even sitting right next to the aircraft don't notice the Ventral Strake (what it's actually called) even when it is there. Most assuredly most of the missing ones you are "seeing" are tricks of the light and them blending in with the sky. They aren't very big and can blend in with surroundings.

rjsampson wrote:

hOMSaR wrote:

Where are you seeing these planes missing the lower part? If they're flying overhead and you're looking at them from below/at an angle, I'd almost guarantee that it's an optical illusion due to lighting. There's no way that 40% of split-scimitar 737s are missing a piece of the winglet.

I've seen plenty of split-scimitar 737s overhead where I swear they were missing the lower strake, but when I eventually got a good enough view at a different angle, I could then see them quite clearly.

On approach to 27 in San Diego. I too had thought that may be the case the first couple of times, after watching countless approaches, I am 100% certain I've seen several aircraft single ventral strake removed on many aircraft, on one wing only. I have a pretty good sample size, too. I take my dog to a park in Balboa Park, which has outstanding views of approaching aircraft. Not directly under the approach. And of course, being the AvGeek I am, I almost always at least glance at the approaching aircraft.

Additionally, I've seen the approach from many different locations and consistently observe the same thing. Now, 40% may be a subconscious exaggeration given that they really stick out, but it's not an inconsiderable number. Maybe one of the SW drivers here or MX would have insight?

If you are seeing many SWA aircraft with 1 missing ventral strake then you are seeing an optical illusion. SWA requires removal of both strakes for CDL if one is damaged. So right off the back you will not see an aircraft with one totally missing. Secondly I took a quick look in records at our -800 fleet and I only found one aircraft that had the strakes removed in the last six months.

B6JFKH81 wrote:

Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.

Has anybody BOTHERED to look at the Configuration Deviation Log? It might surprise you..

strfyr51 wrote:

B6JFKH81 wrote:

Considering the Split Scimitar retrofit assemblies are all based on the existing blended winglet, missing a “dorsal” fin of the winglet would cause the entire winglet assembly to be missing as the ventral fin is a part of the assembly from what I can see so you can’t have one missing without the other. Not too familiar with the 737 but just looking at pictures it seems it is an all-or-nothing wing tip assembly.

Has anybody BOTHERED to look at the Configuration Deviation Log? It might surprise you..

Considering I don't have access to that (if you couldn't tell by my screen name, my airline operates A320/321 and E190 so a 737 manual is not something in our library), it might surprise you that I couldn't look up that information...