What is this fitting?

[Widow]

2R, are you talking about CID's pics?

With respect to the insert and fitting in question:

"Semiquantitative EDS analysis of the threaded insert gave results that were consistent with the UNS C28000 copper-zinc (brass) alloy."

"Semi-quantitative EDS analysis of the carburetor inlet fitting gave results that were consistent with the UNS C28000 copper-zinc (brass) alloy".

Boosted, I'm not sure if that is an NPT "in" ... I'll try to find out.

ruddersup?, don't NAPA supplied parts have an identifying mark?

[Akira]

as soon as I saw that I could of told you it was an npt reducer, I though it was 1/4-1/8 though, can't believe it took that long for you guys to figure it out.

[Widow]

Yes, but can you tell me what the fittings "normal" use is???

[2R]

Yes, i was commenting on cids pics the differences are subtle but there if you look in cids pics.

To give an accurate assesment of the work done it might be helpful to discuss the pictures with the person who last worked on the fittings.
Sorry it has taken so long as i did not want to give a wrong opinion on something so serious .My usual rants will not do as i know this means a lot to us all.

Do the technical records show any source for the fitting ? Green tags ?

[BoostedNihilist]

Widow, NPT fittings are used everywhere. Due to the commonality of your fitting it is likely that the part you have has five or more different "proper" applications, and many more 'creative' applications. My dads old tool box was filled with the things, I suspect they were used in air brakes applications since he was a heavy duty mechanic, but there are plenty of other places that part could be used.

The other problem is identification. Without a mark it will be virtually impossible to identify the lineage of your fitting. You might get lucky and come up with a visual identification, but many companies produce very similar fittings and the production run of that particular fitting might have ended... I just don't see a straight path to the manufacturer and I am used to looking for obscure parts.. sometimes you're just screwed.

My suggestion, go to home hardware, napa, wherever they are sold and buy some, they are inexpensive... ask the people who sell them what they would use them for.. I somewhat doubt 'airplane' will be an answer they will come up with.

[Widow]

Thanks boosted, we've looked around, and asked around ... we can't find an exact match. It isn't essential, it would just be nice to know.

2R, the person(s) who last worked on the fittings ... yeah, we'd like to talk to them, lol.

There is nothing in the logs about this fitting being installed. There might be something in the work orders that TSB/TCCA collected, but we've not had access to those.

[2R]

Do you have a picture looking straight into the female thread on the carb ?
The reason is to check to see if it is a tapered thread.If it is tapered the inside narrows the further down the thread goes.
If it is not a tapered thread It might be a straight thread or more commonly known as parallel thread.It could explain the galling of the thread .Although most galling of threads is caused by misalignment by the fitter or mechanic

If it is a straight thread the correct fitting would look more like the first cid picture .Although it may have been on there for a long time .And the best guys to talk too would be the AME's at the spit who know these machines intimately and can give you a better idea as to what is normal for that machine although someone posted it was supposed to be steel in that area .

Someone should talk to the guys who last worked on this engine to see if they can remember doing similar work on other planes .

[Widow]

No, I don't have a pic like that, and the fitting is no longer in my possession. I have, however, been told that it is a tapered pipe thread.

I have talked to AMEs who work on R-985s regularly. None of them think that fitting should have been there.

From an engineering request from the regional department:

One source says fitting should be an AN 822-80 90 degree elbow but XX is trying to
find out if fitting should now be steel. Once the TSB is in possession of the hose and fitting,
examine the fitting to determine the material, examine the threads on the fitting to verify the mode
of failure. TSB investigators believe this is an overload failure due to tensile loading of the
hose/fitting either at impact or when the engine separated from the fuselage; however, both the
engine driven fuel pump and the carburetor were recovered with the fuselage, which may indicate
the hose and the carburetor fitting were never subjected to high tensile loading. Also, if the fitting
turns out to be brass, dissimilar metal corrosion might have contributed to the fitting pulling out of
the carburetor while both were submerged in salt water for 6 months.

[BoostedNihilist]

edit hmm, wrong button

[Akira]

There's so many places that npt is used that I don't know what the right answer is.
I've personally used them on phnumatic distribution blocks, for oil distribution, to make manual boost controllers, to make vacuum t's... Oh and 1/4npt is standard on most airtools.

also some not fittings will come with a thread sealant already applide this maybe what caused the excessive corrosion in the threads and not the body. google granger valve boost controller, and you should find what I meen, I'd link you but I'm on an iPhone and cant cut and paste

[Strega]

Did this fitting in question fail?

It looks as though its integrity has not been comprimised,

Also, it seems to me that a 1/4 fitting is small to feed a r-985 at take off power, Anyone?

[2R]

After looking very carefully at the pre cleaned fitting .

It has damage consistent with a cross threaded damaged fitting.

[Bulawrench]

I have a 985 carb in my hand. They come with either a -8 fitting or a -10 steel fitting.
I prefer the -10 just because it is larger. The carb is pipe thread. There is no other correct configuration.
Even if i installed a new fitting it would be unlikely that it is recorded in a work order. An overhauled carb would come with the fitting installed and ready to go.
Does the hose have a manufacture tag. This is another area that is questionable. If i don't see the tag on a main fuel line it is gone. They are to be changed at every engine overhaul.

[Widow]

The fitting and it's associated parts are being examined to determine how the damage was incurred. The fuel system came up with the fuselage in July '05 and has never been examined.

I do not know if the hose had a tag, I do not have access to parts or logs right now.

[BoostedNihilist]

google granger valve boost controller

not to derail this thread but a grainger valve fresh out of the box does not make a very nice boost controller. They tend to spike, which if you are running on the hairy edge of stoich is a bad thing. You need to take it apart and move the ball from one end of the spring to the other... thus creating a hybrid g-valve. This system will still spike, but not nearly as much as an unmodified g-valve.

[Akira]

google granger valve boost controller

not to derail this thread but a grainger valve fresh out of the box does not make a very nice boost controller. They tend to spike, which if you are running on the hairy edge of stoich is a bad thing. You need to take it apart and move the ball from one end of the spring to the other... thus creating a hybrid g-valve. This system will still spike, but not nearly as much as an unmodified g-valve.

MBC < EBC. ill be running a mac solenoid valve this summer with my ems.

[Strega]

No one answered.

did this fitting fail?

it looks to me like it didn't.

if it didn't fail, why are we talking about it?

[Akira]

No one answered.

did this fitting fail?

it looks to me like it didn't.

if it didn't fail, why are we talking about it?

Because its the wrong fitting. and it would most likely fail.

[2R]

From what appears in the pictures .The fitting did not fail .The fitting was not installed with the practices of good workmanship .Whomever installed that fitting installed the external (Male) thread into the internal thread (female) in such a manner that damaged the thread.
I would bet my licences on that opinion.I have installed high pressure piping and tested it to pressures of 10,000 psi .That fitting would have blown off at pressure or vibrated out as it did not have the proper metal to metal contact that is required for a safe installation .Even if the hose was clamped close to the fitting the threaded joint would have been weakened to well below the design specifications of an NPT threaded fitting properly installed.

[Strega]

From what appears in the pictures .The fitting did not fail .The fitting was not installed with the practices of good workmanship .Whomever installed that fitting installed the external (Male) thread into the internal thread (female) in such a manner that damaged the thread.
I would bet my licences on that opinion.I have installed high pressure piping and tested it to pressures of 10,000 psi .That fitting would have blown off at pressure or vibrated out as it did not have the proper metal to metal contact that is required for a safe installation .Even if the hose was clamped close to the fitting the threaded joint would have been weakened to well below the design specifications of an NPT threaded fitting properly installed.

I dont think you'll ever see a brass fitting on lines rated to 10kPSI MWP,

Find me the specs for the NPT thread on this fitting. How do you base your conlclusion that this fitting would have been weakend? Are you a trained metalurgist?

Also, would it not have been possible for some ham handed moron mechanic that works for the government to have damaged this fitting when removing it? perhaps he forgot the addage, lefty loosey, righty tighty.

[2R]

Look the pictures carefully
The damage is on the first three threads .Swarfing of the threads is present at the crack .Both are clear indicators of cross threading .If the fitting failed you would expect to see signs of fitting failure .The damage is inconsistent with a pressurized failure .The thread damage would be different .The threads would have been deformed in the direction of travel.In an over presuure situation or explosion the thread and metal damage would indicate the direction of separation . I have seen that kind damage on pipe thread after an explosive event caused by overpressure on a loose fitting .That kind of damage would still be present even with the corrsion .Just as the cross threading evidence is present .
There is also clear evidence of the damage being mirrored on the internal threads matches the damage on the external threads proving a mechanical event of damage occured in the fitting of the two pieces .Because there is clear evidence of corrosion on top of the mechanical damage .I would think it safe to state that the damage occured before it came into the possesion of anyone else after the event.The key is the mirror damage to both threads on the threads before the corrosion.
I hope that answers your question .
That is what the evidence suggests to me .However someone with more experience with forensic science may see something i do not .And those labs have such wonderful equipment i would bet they can get to the truth .I can wait to see what they say .

http://www.webtec.co.uk/techinfo/pipeco ... peconn.htm

This link explains the difference between NPT and NPTF after you read it you may understand the difference's in NPT when used in different applications .There are reasons why Pipe Engineers make more than Plumbers .And why you never use a fitting without a makers mark on it .No matter where it came from .As there is a significant difference that may not appear for the first ten years of use but when it does show up it may just blow up when used in fuel lines .

[Strega]

Pipe Fittings > Shape > Adapter Type > Material > Pipe Size
View catalog pages (2)
Compare products (3) Brass Pipe Fittings and Pipe
3 products match your selections
Shape Adapter
Adapter Type Female x Male Adapter
System of Measurement Inch
Pipe Size 1/2" reduced to 3/8"
Pipe to Pipe Connection NPTF x NPTF
Material Yellow Brass

Maximum Pressure (psi)
PSI (pounds per square inch) is the amount of pressure a pipe fitting can endure.

High Pressure
1200
Extreme Pressure
3200


Specifications Met
American Society for Testing and Materials (ASTM) | Military Specifications (MIL) | Society of Automotive Engineers (SAE) | Not Rated


These 3 products match your selections
Specifications Met Each
1200 Maximum Pressure (psi)
Not Rated 50785K29 $3.60

Not Rated 50785K291 4.28

3200 Maximum Pressure (psi)
American Society for Testing and Materials (ASTM), Military Specifications (MIL), Society of Automotive Engineers (SAE) 4757T124 $11.02


not bad for $11!

[Akira]

wrong fitting it was a copper/zinc fitting not extruded yellow brass bar stock, as stated above. try 9151K28.
This is something that the mech just got at homedepot, CT, or local hardware store. so dont expect it to be a med-hi pressure fitting.

[Bulawrench]

This is a beaver fuel line. 5 psi or 6 if it was military.
I have pulled aluminum fittings from this area.
As far as this fitting Widow, it is just blatant negligence.
A good case for a human factors video.

[Widow]

It was a military Beaver.

Do you mean aluminum fittings like the one in the bottom right corner here?