Turbo V-clamp

[EricJ]

8 minutes ago, shawnd said:

Couldn't have captured it better! Maybe they test the aviation ones for repeated heat cycles and tolerance up to certain temperature ranges. I tried looking at tech specs on the Summit Racing site but couldnt find it on their site. On a race car - if you don't already have a fire restraint system, you can still pull over, unlatch your harness and jump out. Up in the air, we are SOL'ed and can't just crash the plane to "get to a quick exit".

OTOH, the race units are typically holding back a lot more boost at higher temps, with more frequent heat cycles.   So they're pretty well exercised from a reliability/robustness point of view, assuming you get a decent one with such a deployment history.

 

[jetdriven]

but they dont run cherry red at 1650 degrees for 6 or 7 hours at a time, for 2000 hours or more.

[dzeleski]

22 minutes ago, jetdriven said:

but they dont run cherry red at 1650 degrees for 6 or 7 hours at a time, for 2000 hours or more.

They absolutely do. Cherry red also starts way cooler than 1650. That’s also the exhaust flow mass temp not the pipe temp. NA engines can easily get a header cherry red. Modern turbos can tolerate way more than what these airplane turbos can. Modern turbos are water and oil cooled, 1700+ isn’t unheard of (turbo still won’t be very happy here though).

I’ve seen more welds fail than clamps, but that also has to do with solid mounting being incredibly tough on parts. 

Edited January 15, 2024 by dzeleski

[jetdriven]

10 minutes ago, dzeleski said:

They absolutely do. Cherry red also starts way cooler than 1650. That’s also the exhaust flow mass temp not the pipe temp. NA engines can easily get a header cherry red. Modern turbos can tolerate way more temp than 1650 due to being water and oil cooled, 1700+ isn’t unheard of (turbo still won’t be very happy here though).

I’ve seen more welds fail than clamps, but that also has to do with solid mounting being incredibly tough on parts. 

what about this part, you took issue with 1/3rd of my statement. 

for 6 or 7 hours at a time, for 2000 hours or more.

 

I cant believe we are even talking about substituting Amazon, ebay, or Summit racing style V-band clamps for the real thing. Even the real items get you killed.

 

[dzeleski]

1 minute ago, jetdriven said:

what about this part, you took issue with 1/3rd of my statement. 

for 6 or 7 hours at a time, for 2000 hours or more.

 

An average turbo OEM car is gonna have a TIT right around 1600F every time it’s cruising down the highway. And it’s doing that for way longer than 2000 hours.

[jetdriven]

Ive had plenty of turbo cars and none of them glow unless youre producing 75% power continuously and then shut it down hot.  None of them produce airplane levels of power for anything beyond about 12 seconds anyway. There is no comparison.

[dzeleski]

1 minute ago, jetdriven said:

Ive had plenty of turbo cars and none of them glow unless youre producing 75% power continuously and then shut it down hot.  None of them produce airplane levels of power for anything beyond about 12 seconds anyway. There is no comparison.

Yes because they are water cooled. The turbo acts as a giant heat sink. Of course the load is different but the temps are still similar for very long duty cycles.

Even after just some ever so slightly spirited driving a turbo will start to glow on an OEM modern car. My b58 powered car does it after just a single small pull. If you shut the car down too soon the ECU will keep the coolant pump and radiator fan running to cool everything down. You won’t notice it glowing during the day but pop your hood at night and I’ll bet you see some red.

[dzeleski]

31 minutes ago, jetdriven said:

I cant believe we are even talking about substituting Amazon, ebay, or Summit racing style V-band clamps for the real thing. Even the real items get you killed.

 

I don’t think anyone would ever actually do this unless they were stuck somewhere and needed to get home or reposition for a fix on a certified airplane. The really nice clamps are usually 50 bucks for 2.5” and larger (not from summit). I could understand that cost going up by 100-300% for testing and validation, paperwork, etc. The fact that charging 500+ dollars for what is a 50 dollar part is just lunacy. And this kinda thing is killing GA.

[EricJ]

1 hour ago, jetdriven said:

Ive had plenty of turbo cars and none of them glow unless youre producing 75% power continuously and then shut it down hot.  None of them produce airplane levels of power for anything beyond about 12 seconds anyway. There is no comparison.

You need to go try endurance racing sometime.   Turbos making way more power and boost for 24 hours at a time including some heat cycles and lots of variations.   The stress is many times higher.   An aviation turbo lives a much happier life.   Steady-state operation is not that hard on equipment. 

[Steve Dawson]

From what I understand the RayJay turbo applications came from a diesel Caterpillar engine. They run for hours at reasonably hot temperatures so if an original part number (not Continental or Lycoming number but their source) I think it could be a start for finding a more reasonable priced replacement. That's if it's legal 

[Schllc]

Is there a way to reference how many actual catastrophic failures there have been of these clamps. 
Everything in aviation is about risk mitigation, not elimination. 
For example, if these clamps are failing at every 500 hours, that is a pretty elevated risk.

However, if they are failing every 10,000 hours that is a different order all together.

Furthermore, were the failures under normal operating conditions, or were they over torqued or installed improperly?

I don’t understand the calculus that the FAA uses to declare an AD, it doesn’t seem like a uniform standard and seems much more arbitrary. 
When calling around for this part, a major sales and service center was contacted and they said that no one had ordered this part or even inquired about it since March of 2023. 
If this was such a prevalent and chronic problem, wouldn’t you think more people would be looking for the part?  How many of us on this forum have had a failure or are grounded because their part didn’t pass inspection?

Safety is paramount, and regulations are not a bad thing, but sometimes I think the heavy handed methods are counterproductive. Unless the object is to frustrate piston GA into extinction.  If that’s the goal then they are running a tight ass ship! 

[MikeOH]

5 minutes ago, Schllc said:

...sometimes I think the heavy handed methods are counterproductive. Unless the object is to frustrate piston GA into extinction.  If that’s the goal then they are running a tight ass ship! 

That's been my cynical, but reasoned opinion, for quite some time!

[N201MKTurbo]

Well, we have had some wonderful discussion here. No data, just subjective impressions, who knows what actual data would show. Good luck getting it. The FAA has the same problem….

[Pinecone]

15 hours ago, jetdriven said:

but they dont run cherry red at 1650 degrees for 6 or 7 hours at a time, for 2000 hours or more.

Well, they do run 24 hour races, and they do run glowing hot.  And I don't think they are an every race replacement item.

I

[Pinecone]

9 hours ago, Schllc said:

Is there a way to reference how many actual catastrophic failures there have been of these clamps. 
Everything in aviation is about risk mitigation, not elimination. 
For example, if these clamps are failing at every 500 hours, that is a pretty elevated risk.

However, if they are failing every 10,000 hours that is a different order all together.

Furthermore, were the failures under normal operating conditions, or were they over torqued or installed improperly?

I don’t understand the calculus that the FAA uses to declare an AD, it doesn’t seem like a uniform standard and seems much more arbitrary. 
When calling around for this part, a major sales and service center was contacted and they said that no one had ordered this part or even inquired about it since March of 2023. 

From what I understand, there were a couple of failures of clamps that caused mishaps.  But from the pictures, they appeared to be rusty and not airworthy to the naked eye.  

Hmm, heck, as $30 each from Summit, even if you replaced it every 25 hours, it would be cheap compared to $1200 - $1500 every 500 hours.