R

Rupester

Well Known Member
I just received the two AN816 fittings I ordered from Spruce to reinstall the replacement red cube. This is the second time I've received two of them on the same order that are notably different. Coincidentally, the last time I ordered two of these (again, from A/S) the same thing happened. Anybody else notice this? Should I prefer one "style" over the other?

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Steel

Terry. In a recent thread I posted regarding
piping up my red cube. A few guys tuned in and recommended
Steel fittings.
 
Thanx, Al. It depends where it's located and whether or not it's solid piped or with flex hoses. I'm confident Al will work fine for my installation.
 
Rupester said:
I just received the two AN816 fittings I ordered from Spruce to reinstall the replacement red cube. This is the second time I've received two of them on the same order that are notably different. Coincidentally, the last time I ordered two of these (again, from A/S) the same thing happened. Anybody else notice this? Should I prefer one "style" over the other?
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You should get a genuine AN/MS spec fitting. Anything else is fraud; the staff at Aircraft Spruce should know the difference.

We had this conversation a few years ago.
 
Both styles are allowable (my interpretation of note a)

AN816 drawing note a: "at the option of the manufacturer, the smaller diameter may be drilled through the fitting from end-to-end."

Not sure if I'm interpreting this note correctly.
 
Are they both marked "AN"?

At one time there were unmarked fittings getting delivered through the aircraft channels...
 
Per the Spruce catalog, the fittings are AN816 4-4D.

Referring the pics above:
The one on the left, darker in color and less shiny, has stamped marks on each of three hex sides: HK, D, and AS
The one on the right, which subjectively appears to be of higher quality, has stamped marks on two of the hex sides: RE, and AS-D

The ones I ordered a month or so ago have identical marks.

FWIW
 
Rupester said:
The one on the left, darker in color and less shiny, has stamped marks on each of three hex sides: HK, D, and AS
The one on the right, which subjectively appears to be of higher quality, has stamped marks on two of the hex sides: RE, and AS-D
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I am sincerely pleased to hear about marking. It sounds right....manufacturer ID, AS5195 standard, aluminum.
 
Bob Axsom said:
What is the ID of the holes on both sides of both fittings? The D means aluminum which is consistent with blue fittings. The AN816-4 has only two pipe thread sizes:

AN816-4 = 1/8" pipe
AN816-4-4 = 1/4" pipe

Bob Axsom
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To be a bit more precise, from the Mil Spec -

1/8 NPT 0.188 in. diam +/-0.003

1/4 NPT 0.261 in. diam +0.004/-0.003

These should be the standard hole diameters for a pipe fitting.
 
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Bob Axsom said:
From az_Gila's dimensions it appears that you have one AN816-4D and one AN816-4-4D and if this is true Aircraft Spruce needs to be notified - they may have mixed stock.

Many many years (over 45) ago I was the foreman over Receiving Inspection for the McDonnell Douglas Electronics Company and this kind of thing happens. I worked in Missouri at that time and the Uniform Commercial Code was the law in effect. It required timely inspection and notification of the nonconformance which the inspectors initiated by writing a Material Review Record, submitting it to the Material Review Board (MRB) and placing the shipment in bonded storage. The disposition was usually RTV (return to vendor). Since you ordered AN816-4-4D I assume you do not want the 1/8" restriction in the application. You need to verify what you have and contact Aircraft Spruce to notify them of the discrepancy if it is as it appears to be - even if it is of no consequence to your application this could be a safety of flight issue for someone else in another application.

Bob Axsom
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I certainly don't see it that way.

From the original post he has two fittings that have identical exterior dimensions, ordered as AN816 4-4D - 1/4 pipe to 1/4 inch flare.

The only difference is that one manufacturer has elected to take the option of having the flared tube end inner diameter dimension carry on all of the way through the part.

For a -4 flared tube end fitting that inner dimension is 0.172 in. +0.003/-0.004

So one has a hole size of 0.172 at the pipe thread end and the other has the optional "drilled out" hole size of 0.261.

Exactly like the second picture in the first post.

I believe both parts are in specification.
 
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Gil's observation is correct ...

The inside diameter of the flared end of both fittings is identical, thus the flow restriction would be about the same. The darker color fitting opens to a much larger diameter for the npt end; while the shiny fitting carries the smaller diameter all the way thru.
The previous similar pair of not-quite-the-same fittings were unknowingly installed on the defective (i.e. threads unsealable) red cube and the aircraft ran and flew just fine, so there appears to be no problem with flow restriction. I'm putting in the replacement red cube (thanks again to Dynon!) today, and in getting ready to do so, noticed that the two new AN816 fittings - and the last pair - exhibit that same slight difference in design.
I was just surprised that all AN816 4-4D fittings would not be identical, given the generally higher quality standard for aircraft-grade hdwe. Either Spruce has their bins mixed, or this an allowable variation within the spec for AN816 fittings.
 
Rupester said:
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I was just surprised that all AN816 4-4D fittings would not be identical, given the generally higher quality standard for aircraft-grade hdwe. Either Spruce has their bins mixed, or this an allowable variation within the spec for AN816 fittings.
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As mentioned much earlier, it is an acceptable option (I wouldn't really call it an "allowable variation") in the AN 816 specification.

I bet a #19 drill will nicely slip into the smaller hole at the pipe thread end of the fitting in question.

A 1/4 inch drill bit should be a somewhat looser fit into the bigger pipe thread end hole.


Bob, I respectfully disagree, the specifications show that the original question - "Why are they different?" - has been answered.

Both parts are AN 816 4-4D parts and are within specification.
 
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Bob Axsom said:
Rupester, please measure the dimension across the wrenching flats and the overall length of the fittings as well, as precisely as you can and provide that information here with the respective hole diameters. The wrenching flats on a AN816-4-4D should be .063" (~1/16") larger than the AN816-4D and the overall length should be 1.375" for the AN816-4-4D and 1.109" for the AN816-4D.

Bob Axsom
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Bob,

No need. Just look at the two parts in the original post.

They are clearly the same length and clearly have the same pipe thread diameter. You are asking to see if there is a 1/4 inch length difference...:rolleyes:

The case really is closed...:)
 
This is an interesting in valuable thread. A guy is asking a sincere question. And some people are providing patient and informative solutions. But can I just suggest that some of the snark -- where it exists -- be toned down a bit. It only serves to make people less reluctant to turn to people for help. If we're patient enough to build airplanes, we can be patient enough with people looking for some help.
 
Bob Axsom said:
I agree, but If we can get the dimensions out here I think we should so everyone can be satisfied with that conclusion.

....
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In a non-snarky way, I was satisfied at posts #5 and #7...:)

It is a really interesting allowable option to the spec., and the intial post asked a good question seeing a major physical difference in the parts.
 
Laudable follow-up ...

I received an e-mail yesterday from Jim Irwin at Spruce ... He saw this thread recently and reported that he had both the GA and CA warehouses check all their stock of AN816-4-4D fittings to look for dissimilariy. He reports they found none. he has also offered to replace any of the "odd" style ones with their normal stocked 816s so all mine match. Once again, it is clear we are blessed with some excellent, consciencious vendors who truly care about their customers and their reputation .
 
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