Cabin altitude warning switch

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1 month 3 weeks ago #1358 by dynamics
Regarding functional test of cabin altitude warning switch FAA has recommended:

"Use a  Barfield Pitot Hose, or equivalent 25feet to 40 feet long hose, with fitting #4AN fitting to adapter and quick disconnect (if applicable) to the air data test set. And make sure that the flat side of the adapter is connected with cabin altitude warning switch"

The above explanation raises the question-what is the adapter and how the hose is connected to the switch?

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1 month 3 weeks ago #1359 by Mark
Replied by Mark on topic Cabin altitude warning switch
Picture, please.

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1 month 3 weeks ago #1361 by dynamics
There is neither any figure in the AMM nor any SB containing figures that is incorporated by reference in FAA AD 2022-24-09

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1 month 3 weeks ago #1362 by Mark
Replied by Mark on topic Cabin altitude warning switch
The cabin altitude switch is the easiest component to functional check using the pitot/static test unit. It's just one line from the box to the switch. As far as the connection goes..... your statement states a #4AN. You just need an adapter to get from the hose to the switch (#6 to #4 reducer would be my best guess). Everyone has adapters for MS and AN fittings.

I haven't a clue as to why the statement "make sure that the flat side of the adapter is connected with cabin altitude warning switch" is stated. Just figure out what is needed to connect the two units together.
  
  
 

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1 month 3 weeks ago #1363 by dynamics
I have just sent an email enclosed with picture of the switch. Would you mind spelling out how can I connect the pitot hose to the non threaded sense port of the switch through threaded AN fitting?

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1 month 3 weeks ago - 1 month 3 weeks ago #1364 by Mark
Replied by Mark on topic Cabin altitude warning switch
You're making this out to be WAY more difficult than it needs to be.
  
  
 

You've already stated this is a #4 AN. I can tell it's a female.... even from a side view. Pitot /Static test hoses usually are #6.
  
  
  
You need an adapter.
  
  
 
  
  
You need to go to the flight-line more. This is "so" easy. Practical working skills on the aircraft is a must.... even for engineers.

If the switch has no threads and a proper adapter from the maintenance manual has not been listed then you'll need to use a chamber.....
  
  
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Last edit: 1 month 3 weeks ago by Mark.
The following user(s) said Thank You: dynamics

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