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Bill3558

Cause of oil pressure loss.

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My insurance adjuster told me his experience has been that certified aircraft shops are much more professional than LSA shops. If you have an SLSA airplane, we don’t have the maintenance options certified airplanes have. Every A&P can work on a lycoming or Continental. 
I hope someday it’s the same with Rotax. 

 

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Airplane has been moved to Atlanta. FD and Rotax reps will inspect. Insurance guy said he will keep me in the loop. 
Will advise if I learn anything. 
 

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On 10/15/2021 at 9:55 PM, Roger Lee said:

The fuel Injectioin clamps on the hose are perfectly okay and come that way from FD. These are not the cheap crappy serrated garden hose type clamps. These are used in cars in fuel injection hoses with ratings to 100 psi when properly used. When used correctly these clamps will stay on a barbed fitting like the thermostat right up to destruction when you try to pull them off.

So I'll explain why I disagree with this.

It's not the pressure that I have issues with. You're right that they are just fine for that.

It's the temperature fluctuations. Rubber expands A LOT when its heated and cooled. Fuel pressure hoses do not get very hot because they're constantly being supplied with cold fuel. They might heat soak a little bit when the car is turned off, but it's pretty minor; and in addition, once the fuel is hot enough it will vaporize and absorb heat anyways, acting like a heat sink.

However, these clamps are on oil hoses. That oil can exceed 250 degrees on hot days. That's a LOT of rubber expansion shrinkage (pointed out to me below). And it's highly cyclical.

I have *never* had a banded hose slip off or even leak. I have had worm drive clamps slip off. I have not had a fuel injector clamp slip off, but I admit I don't use them where heat and fluid is a concern. I have had them leak though with age but I am not really going to fault the clamp for that. I do still use them on the balance tube because that needs to be able to be removed and reinstalled with ease and it needs to attach the spring anchor.

You could be right! I might be worried about nothing. I am going to go with what I've had experience with in flight school aircraft for years though, I don't trust screw clamps, even fuel injector clamps, of any kind on the oil system.

At minimum, if I were to use fuel injector clamps, I would safety them. I know this shows a worm drive clamp, but this applies to fuel injector clamps too:

https://www.kartek.com/mm5/graphics/00000001/safety-wiring-hose-clamps-prevents-the-clamp-from-loosening-up.jpg

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11 hours ago, Bill3558 said:

My insurance adjuster told me his experience has been that certified aircraft shops are much more professional than LSA shops. If you have an SLSA airplane, we don’t have the maintenance options certified airplanes have. Every A&P can work on a lycoming or Continental. 
I hope someday it’s the same with Rotax. 

 

Maybe I'm misreading your post, but it is my understanding that every A&P CAN work on a Rotax.  There are a few differences between Rotax and other traditional and non-traditional aircraft engines, but nothing that the FAA says a properly trained mechanic cannot handle.  Rotax is the one that says special training is needed, and in my experience, having taken the classes, any A&P mechanic can easily learn the unique features of the Rotax from manual and supervised training, just the way they learn how to work on a Lycoming or Pratt&Whitney or Franklin or Curtiss-Wright.  Tom Baker could better address this issue than I.

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8 hours ago, Anticept said:

So I'll explain why I disagree with this.

It's not the pressure that I have issues with. You're right that they are just fine for that.

It's the temperature fluctuations. Rubber expands A LOT when its heated and cooled. Fuel pressure hoses do not get very hot because they're constantly being supplied with cold fuel. They might heat soak a little bit when the car is turned off, but it's pretty minor; and in addition, once the fuel is hot enough it will vaporize and absorb heat anyways, acting like a heat sink.

However, these clamps are on oil hoses. That oil can exceed 250 degrees on hot days. That's a LOT of rubber expansion. And it's highly cyclical.

I have *never* had a banded hose slip off or even leak. I have had worm drive clamps slip off. I have not had a fuel injector clamp slip off, but I admit I don't use them where heat and fluid is a concern. I have had them leak though with age but I am not really going to fault the clamp for that. I do still use them on the balance tube because that needs to be able to be removed and reinstalled with ease and it needs to attach the spring anchor.

You could be right! I might be worried about nothing. I am going to go with what I've had experience with in flight school aircraft for years though, I don't trust screw clamps of any kind on the oil system.

At minimum, if I were to use fuel injector clamps, I would safety them. I know this shows a worm drive clamp, but this applies to fuel injector clamps too:

https://www.kartek.com/mm5/graphics/00000001/safety-wiring-hose-clamps-prevents-the-clamp-from-loosening-up.jpg

 

I'm not arguing for or against your point here.  But, Rubber contracts when it heats up. 

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I have never had an "aircraft quality" worm clamp fail in over 45 yrs. They were not Ace Hardware clamps. There are different variations of the clamps to distribute even pressure on the hose. If you use junk they then expect failures. Every new, certified aircraft engine uses them for the last 90 yrs.

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3 hours ago, Skunkworks85 said:

 

I'm not arguing for or against your point here.  But, Rubber contracts when it heats up. 

Fair!

55 minutes ago, Madhatter said:

I have never had an "aircraft quality" worm clamp fail in over 45 yrs. They were not Ace Hardware clamps. There are different variations of the clamps to distribute even pressure on the hose. If you use junk they then expect failures. Every new, certified aircraft engine uses them for the last 90 yrs.

I've not dealt with a certified aircraft that uses clamped hoses for oil, they're fittings... Which I prefer above all else for critical lines.

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Hi Bill, 

Your next problem will be to find a replacement. I have been watching since April for a friend and have not seen a carbureted LS for sale. Barnstormers doesn’t have a SW or LS listed today.

 

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I know. I’ve looked. 
I got a letter in the mail today from “backtothecockpit.org.”  Apparently it’s a thing to experience ptsd after crashing a plane. This group offers assistance to get over it. It came at a good time. I’m grateful to be alive, but I’m also depressed. Not sure I can recapture the joy. 

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18 minutes ago, Bill3558 said:

but I’m also depressed

Know the feeling.  I ground looped my Husky on the way to Oshkosh... haven't flown since.  Put my heart and soul (and $) into learning everything I could about tailwheel... and I failed.  Too many shoulda coulda's to count.  My "Incident" (that's an FAA technical term) was minor in the scheme of things, but it was a big blow to my confidence and flying career.  

I am now working on getting back into the swing of things.  I will bet you will too Bill... 

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Sorry to hear your story Andrew. I’m hoping that both of you are in the air soon!

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13 minutes ago, AGLyme said:

Know the feeling.  I ground looped my Husky on the way to Oshkosh... haven't flown since.  Put my heart and soul (and $) into learning everything I could about tailwheel... and I failed.  Too many shoulda coulda's to count.  My "Incident" (that's an FAA technical term) was minor in the scheme of things, but it was a big blow to my confidence and flying career.  

I am now working on getting back into the swing of things.  I will bet you will too Bill... 

They say you have to get back on the horse. The sooner the better.

Bill, glad that you are OK. That's the main thing to consider.

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Anticept,

First I never use garden hose cerrated hose clamps. Old school and not keeping up with the times. For some it's hard to let go of tradidtion. They are too easy to over tighten and strip and aren't always great at a good 360 degree seal. Plus they cut into the rubber.

When Wurth Zebra clamps, fuel injection clamps and Oetiker clamps are used PROPERLY then they will not come off. I have tested these on fittings clamped in a vise and the hose ripped off and never moved on the fitting.

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There are no clamps on oil lines for certified probably since the Wright brothers. I don't like them on a CT. I will soon have AE701 or 666 hose with the correct end fittings. Also a lot less chance of a kink. Also won't have to change them for a while. Just me.

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22 hours ago, Bill3558 said:

I know. I’ve looked. 
I got a letter in the mail today from “backtothecockpit.org.”  Apparently it’s a thing to experience ptsd after crashing a plane. This group offers assistance to get over it. It came at a good time. I’m grateful to be alive, but I’m also depressed. Not sure I can recapture the joy. 

I had a little concerned myself about either apprehension or straight out fear flying after my forced landing and nose over. I wasn’t able to get back up for about three months. Nonetheless I had a great time and didn’t feel any fear or apprehension. I know this isn’t the case for everybody but here’s your sample of one.

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On 10/18/2021 at 8:44 AM, Skunkworks85 said:

 

I'm not arguing for or against your point here.  But, Rubber contracts when it heats up. 

 

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I don't see how. It has a positive coefficient of thermal expansion. A rubber hose is not a rubber band.

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1 hour ago, GlennM said:

I don't see how. It has a positive coefficient of thermal expansion. A rubber hose is not a rubber 

Schematic illustrations of lattice modes for a chain of atoms. (A) Longitudinal optic (LO) mode leading to PTE through asymmetry of the pairwise bonding potential shown in Figure 1. (B) High energy transverse optic (TO) mode that greatly shortens the chain giving large NTE as the vibrational amplitude increases with temperature. (C) Low energy transverse acoustic (TA) mode leading to more modest NTE as temperature increases.

 

 

image.png

 

Structural negative thermal expansion results when the shortening effects of the transverse phonon amplitudes due to bending or torsional motions outweigh the expansion effects of the longitudinal modes.

So yes, a single unlinked polymer will expand, but the microstucture of multiple linked polymers will cause a structural negative thermal expansion.

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On 10/18/2021 at 7:42 PM, Roger Lee said:

Anticept,

First I never use garden hose cerrated hose clamps. Old school and not keeping up with the times. For some it's hard to let go of tradidtion. They are too easy to over tighten and strip and aren't always great at a good 360 degree seal. Plus they cut into the rubber.

When Wurth Zebra clamps, fuel injection clamps and Oetiker clamps are used PROPERLY then they will not come off. I have tested these on fittings clamped in a vise and the hose ripped off and never moved on the fitting.

I understand, and I acknowledge that there are engineers who are probably smarter than I am who could prove they're good enough, but I've seen some weird issues. I stand by what I said, I do not like clamps like that on oil lines, I'm a band-it or AN fitting kind of person for those. There's just so much temperature flux for such a critical system. I don't even like serrated nipples either... I would much prefer beaded fittings.

Anyways, I didn't know these shipped from the factory with those clamps. I don't like it, but it is what it is I suppose.

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On 10/17/2021 at 8:19 PM, Bill3558 said:

Turns out I flew over a 1900 foot paved strip. 25SC. It’s not on the charts. Just damn. 

If it's not on the chart, it's not meant for general aviation use, or long long been retired. Closed airfields are charted for a time for emergency use before they get removed completely because landing conditions can get downright dangerous from lack of maintenance.

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7 hours ago, Anticept said:

If it's not on the chart, it's not meant for aviation use, or long long been retired. Closed airfields are charted for a time for emergency use before they get removed completely because landing conditions can get downright dangerous from lack of maintenance.


that does not appear to be the case for 25SC. 
 

https://www.airnav.com/airport/25SC

 

From what I can tell there 25SC is a private airfield that is alive and well  

My IFly GPS allows for 25SC as a destination, and has runway information loaded in the database, also indicating that 25SC is alive and well. But when zooming in on the chart 25SC does not appear to exist unless you specifically search for it  

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Ah you are seeing one of the little exceptions that I didn't mention :P: There's a LOT of private fields that aren't charted. Heliports too! These people don't want anyone landing there, so they wont submit the info to the charting authority. Lots of little strips around my area that farmers own that are unlisted, and there's no guarantee the strip or runway is even useable since its unsurveyed.

https://www.faa.gov/air_traffic/flight_info/aeronav/faq/#q3e

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