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Help with early F model oil door DZUS Fasteners


Shadrach

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I’m placing a spruce order shortly and was hoping to buy Stainless steel replacements for both of the countersunk Fasteners on the oil door. The IPC calls for DZUS AJ4-35 which is an oval head. Mine are countersunk and housed within a top and bottom grommet. They look more like large Camloc fasteners. Does anyone have any info on these?

 

Edit IPC calls for FJ4-35

Edited by Shadrach
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Ross,

My oil door on the M20C had a Dzus type fastener, but had wings like a wing nut….  ‘65 M20C…

Made it convenient for checking oil each flight…

I believe the wings oriented with the airflow when locked down…

My plane was a mix of camlocs and dzus depending on location… None were SS, and were prone to light rust all the time…

Best regards,

-a-

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Ross, I've seen a lot of Dzus fasteners on the museum aircraft, but I've never seen a countersunk one. It sounds more like a Southco.

Thumbs 1

A Dzus stud ties into a S-shaped spring wire retainer.

Main Image

The Southco uses a receptacle.

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EDIT. Perhaps I spoke too soon. I did a quick web search and apparently there are counter sunk Dzus fasteners. Another way to tell it's a Dzus besides the spring retainer is that the slot depression is curved not flat since it is made for a Dzus tool and not a screwdriver. 

DzusButton.jpg

 

https://www.specialty-fasteners.com/Dzus-Steel-Countersunk-Flush-p/sku-3345.htm

Edited by PT20J
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29 minutes ago, PT20J said:

Ross, I've seen a lot of Dzus fasteners on the museum aircraft, but I've never seen a countersunk one. It sounds more like a Southco.

Thumbs 1

A Dzus stud ties into a S-shaped spring wire retainer.

Main Image

The Southco uses a receptacle.

Skip

EDIT. Perhaps I spoke too soon. I did a quick web search and apparently there are counter sunk Dzus fasteners. Another way to tell it's a Dzus besides the spring retainer is that the slot depression is curved not flat since it is made for a Dzus tool and not a screwdriver. 

DzusButton.jpg

 

https://www.specialty-fasteners.com/Dzus-Steel-Countersunk-Flush-p/sku-3345.htm

I too was able to find the countersunk studs but it is not clear what other hardware is appropriate for my application. I’ll get some pics tomorrow.

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My battery box access door had the countersink, with the coin shaped curve in the slot…

Never saw the right tool to get it open… but a screw driver worked good enough…

The S-shaped wires had a tendency to rust out over 40 years…. :)
 

PP observations and fuzzy memories only…

Best regards,

-a-

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56 minutes ago, carusoam said:

Ross,

My oil door on the M20C had a Dzus type fastener, but had wings like a wing nut….  ‘65 M20C…

Made it convenient for checking oil each flight…

I believe the wings oriented with the airflow when locked down…

My plane was a mix of camlocs and dzus depending on location… None were SS, and were prone to light rust all the time…

Best regards,

-a-

Mine never had the wing nut to my knowledge. I don’t care for how those look but they are easy to use and reliable. Mine are slotted for a flat head screwdriver and have suffered from decades of people using coins to open them. They’ve seen better days…

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19 minutes ago, carusoam said:

My battery box access door had the countersink, with the coin shaped curve in the slot…

Never saw the right tool to get it open… but a screw driver worked good enough…

The S-shaped wires had a tendency to rust out over 40 years…. :)
 

PP observations and fuzzy memories only…

Best regards,

-a-

I think thats the same fastener as my oil door. Indeed it is an FJ4-35 which is countersunk. 

Edited by Shadrach
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If it has a curved slot, it’s a Dzus. To open and close them you should use a Dzus tool. The most common version is often referred to as a “Snoopy Tool.” It’s the best tool because it fits all fastener sizes. You can use a screwdriver if the fastener isn’t a tight fit, but if it is tight, the screwdriver blade will chew up the slot. Dzus were popular around WW II. I hate the damn things. The springs break after they work harden. Large panels with Dzus all around the perimeter often will only allow you to tighten the last one if they are tightened is some particular order which is not necessarily the same each time you replace the panel.

1478811148_DZUSSNOOPYTOOLAircraftSpruce.thumb.png.55ce9b6c0914997087686b30e7378b88.png

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37 minutes ago, PT20J said:

If it has a curved slot, it’s a Dzus. To open and close them you should use a Dzus tool. The most common version is often referred to as a “Snoopy Tool.” It’s the best tool because it fits all fastener sizes. You can use a screwdriver if the fastener isn’t a tight fit, but if it is tight, the screwdriver blade will chew up the slot. Dzus were popular around WW II. I hate the damn things. The springs break after they work harden. Large panels with Dzus all around the perimeter often will only allow you to tighten the last one if they are tightened is some particular order which is not necessarily the same each time you replace the panel.

1478811148_DZUSSNOOPYTOOLAircraftSpruce.thumb.png.55ce9b6c0914997087686b30e7378b88.png

This is why everyone just uses pennies and quarters.

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Interesting…

Hartwell and Southco both have latches….

The Ovation uses latches… not sure which one they are…. 
 

Kind of look more like the Hartwell pic…

PP thoughts only, trying to add to the scale of the project Ross is taking on….  :)
 

Trying to stay near 100% original is challenging….  For a few AMU more….

Best regards,

-a-

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When I get home I can shoot you the numbers - I picked up replacement t fasteners at SNF for mine with the same setup. 
 

What I can’t help with, and am tuning in to see, is  if someone figures out the proper grommet  and/or retaining clip part numbers so I can quit having to catch mine as they fall out of the panel more often than not on preflights. 

Edited by Pasturepilot
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Interesting cartoon video showing how the spring clip is supposed to work…

https://southco.com/en_us_int/fasteners/emdzusemreg-quarter-turn-fasteners

The retainer… the part I think Pasture is looking for gets mentioned briefly…

Looks like they want you to download their e-catalog to find the various details that go with the Dzus fastener…  which is probably a good idea…

 

 

They have a brief article showing uses and a pic of the various Dzus fastener cores… https://southco.com/en_us_int/resources/Benefits-of-Quick-Release-Latching-for-Escape-Doors-and-Hatches

 

The details about the different fastener heads and the various retainers can be found here…. Go further down the page to see the options…

https://southco.com/en_us_int/fasteners/emdzusemreg-quarter-turn-fasteners

 

Wish MS was around when my Dzus fasteners weren’t constrained….  :)

Go MS!

Best regards,

-a-

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20 hours ago, Pasturepilot said:

When I get home I can shoot you the numbers - I picked up replacement t fasteners at SNF for mine with the same setup. 
 

What I can’t help with, and am tuning in to see, is  if someone figures out the proper grommet  and/or retaining clip part numbers so I can quit having to catch mine as they fall out of the panel more often than not on preflights. 

You making the stock winged version sound better and better!

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