Damage to the landing gear airspeed safety switch?

[xcrmckenna]

Just a few weeks ago I installed a brand new $1,300 landing gear airspeed safety switch. Now I'm having a certification done on my new transponder. I was wondering what it is that a tach does to damage the safety switch during a certification? Are they hitting it with to much air all at once, and just needs to make sure they add the air slowly? Or is it the direction their sending it? We have to check the pitot and static side. Thanks for the help.

 

 

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[carusoam]

Compressed air at 90psig is a lot, when airspeed uses a few psi that can be generated by squeezing/rolling a tube/hose full of air.

Did you see anyone approach with an air gun?

Best regards,

-a-

[xcrmckenna]

Compressed air at 90psig is a lot, when airspeed uses a few psi that can be generated by squeezing/rolling a tube/hose full of air.
Did you see anyone approach with an air gun?
Best regards,
-a-

So it is a pressure issue not a procedure issue? No air gun in sight yet but I'll make sure one doesn't get close to the plane tomorrow...


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[N201MKTurbo]

Any sudden pressure change can damage instruments. If you open the alt static source or a static drain when the static system is at 20000 ft or so, will most likely damage all your static instruments. The same thing could damage the pressure switch.

[dlmorris]

Our switch was damaged by the local static system shop (San Antonio area). He denied it of course.   

[MB65E]

Wow, I just thought of an great gear up senecio. During an pitot static check!! It will retract with AS applied. Be careful!

Most shops that Do certs are pretty careful, I found a few that are more careful the AS/ALt changes than I am. I still Babysit the airplane during the cert. 

-Matt

[DonMuncy]

2 hours ago, dlmorris said:

Our switch was damaged by the local static system shop (San Antonio area). He denied it of course.   

My VSI was damaged when a cover on the pitot static system fell off during the testing process. My guys had the instrument repaired, apologized, and said that accidents like that happen on occasion, and it is one of their costs of doing business. (Avionics 1st at Dallas KRBD) 

[KSMooniac]

I'm so glad my '77 still has the squat switch on the main gear.

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[xcrmckenna]

I'm so glad my '77 still has the squat switch on the main gear.

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But then you wouldn't have the opportunity to have an extra $1,300 sitting behind your panel like this....


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[KSMooniac]

FWIW, I installed an aftermarket switch kit to run a Hobbs meter to record flight time just for my own giggles. I think the kit was under $100. It would function fine as a replacement, but the approval is another story...Perhaps the next owner with this problem might try to find a friendly IA and try it as a minor mod. The FAA has already allowed substitution of common electrical components to keep old planes flying...this wouldn't be too much of a stretch.

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[Hank]

Part of the writing is cut off (wrapped out of sight), but it looks like it says "Max Pressure 50 in H2O."  Otero that standard atmospheric pressure (14.7 psi) is about 32 FEET of H20, while 50" is a mere 4 feet. How many 14.7s are in 90? Several! Also, the shop air at work, supposed to be 90 psi, typically runs 100-105, which is another 32 feet . . . Should be a couple thousand inches of water.  

Be careful out there! Put a piece of surgical tubing on the pitot tube, pinch it closed and roll slowly until you have the desired ASI reading.

[Guest]

I would think that if the airspeed switch was damaged during a pitot-static test, other instruments in the system should or are as well?

Clarence