What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

SAIB (Special Airworthiness Info Bulletin) on Switch Style Circuit Breakers

Walt

Well Known Member
I've never been a fan of the switch/breaker combo, if you are using these or plan on using them, you need to read the latest SAIB.

LINK TO SAIB
 
I like breaker switches. We've been changing out those W31 types for near 15 years. Just because those have always been junk is no reason to dis all breaker switches.
 
I like breaker switches. We've been changing out those W31 types for near 15 years. Just because those have always been junk is no reason to dis all breaker switches.

What are you replacing the W31's with? I have six in my -4; five for lighting and 1 for fuel pump.
 
I think it started with Westwinds and then spread to Beeches and twin Cessnas. If I'm remembering right, there is a braided strap in there that flexes with switch actuation. The strands break and they get fuzzy inside and short. The certified replacements are ungodly expensive. I like the ETA breaker switch series, but they are rectangular rockers so it might not work for you
 
What are you replacing the W31's with? ...

Since the SAIB recommends replacement every 2000 hours, I'd just replace mine with more W-31's. I wouldn't change engine brands just because it was recommended for replacement every 2000 hours...
 
The SAIB says 2% failure at 2000 cycles, but recommends 2000 hours. Seems like too many hours to me. If my plane gets to 2000 hours (or even 2000 cycles) on the switch/breakers with me flying it, I'd happily replace the two S/Bs I have.
 
Wow

2000 cycles is an extremely low rating for an electrical device.

The manufacturer is saying they are safe as long as you don't use them much :eek:

Mark
 
Last edited:
my experience

I just replaced two W31 switchable breakers in our RV7a during the condition inspection because the breaker used for the boast pump failed. While I had the bus bar apart, I replaced another one also. I now carry two spares in my box of stuff I carry. Since our RV7a is 6 years old this month, I guess I will be changing these two every 5 or 6 years.
 
FYI: Circuit Breaker Switch SAIB (Special Airworthiness Information Bulletin)

I have some of these installed in my RV-4, in fact, they are my primary method of control over my primary electrical systems:

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/dc7bd4f27e5f107486257221005f069d/469f896b8a88d2a886257b2d0066ed6c/$FILE/CE-13-22.pdf
 
If I read correctly, the part numbers called out were all 50 Amp breakers. I know I don't have any of those! (the -50 at the end is calling out the amp value)

Vince
RV-7
 
Sounds like much ado about nothing. I have these all over my panel and have had one issue with the amp size not being large enough for the load.

2% at 2000 cycles with an average of one cycle per flight hour is the same as my recommended TBO engine overhaul which will concern me when I get that far.

50% at 6500 hrs 90% or more of those flying RV's will never see that amount of usage on thier aircraft in the owners lifetime. I see 15 year old Rv's in the ads all the time with less than 700 hrs on the airframe.

Put an extra 5 and 10 amp W31 breaker ( $50 cost) in your emergency haul around bag and forget about it.

John Morgan
 
EDIT: I still don't like these numbers for a switch.

Analysis of available service difficulty report (SDR) data indicates 2
percent of those analyzed failed by 2,000 cycles; 50 percent of those analyzed failed by 6,500 cycles, and 90 percent of those analyzed failed by 10,000 cycles.
 
Chat with Tyco

I just went to the Tyco site and did a "chat" with one of their guys. He had no idea what SAIB even was. I sent him the link and he was baffled. He said he would have to talk to engineering and get back to me.

I just read this as I was installing the switches in my panel. Almost every switch I have is a Tyco W31. I do not want to put switches in that are going to be a problem.

I assume that many of the RV's flying today have these same switches and I haven't heard of that many problems, but if people are carrying spares, that is not good. I have never had a switch go out in any of my cars or trucks. Maybe I should get auto switches?


Those Klixon 7270's are expensive. At $120 a switch, that sounds like crazy money. Maybe carrying around spare switches is the answer. I am stumped. I will post if tyco gets back to me.
 
Maybe carrying around spare switches is the answer.

Many RV'ers also carry spare tire inner tubes in their onboard emergency kit, and for the same reason. Parts wear out and break - if it's practical to do so, carry a spare.
 
TE engineer

I tried to find out from Tyco what the story was. This is what I got back:

Hello,

Thank you for contacting TE Connectivity.

My engineer said: "This is the first I heard of this. There is really little that I can say other than the FAA recommendation be followed."

Dale


Thank you for your inquiry,
TE Connectivity
Technical Support Center
http://www.te.com
For Support: http://www.te.com/help
800-522-6752 x2


I guess I will just take the chance and hope I am on the good side of the odds and change as they **** out!
 
10 amp TYCO W31 series toggle Circuit Breaker failure.

Resurrecting an old post.

Today, after run up and just prior to take off, I switched the TYCO W31 toggle breaker (10A) for my Airflow Performance fuel pump on and got nothing.

With the engine running I can't hear the pump operating so I look at my EFIS to see if I get an indication of rise in fuel pressure and an increase in amperage. Again, nothing. I returned to the hangar to investigate. Result, bad TYCO.

Before reading this thread, I replaced the TYCO with another TYCO and it works for now.

The KLIXON 7270-1 circuit breakers appear to be more optimal.

Do any of you use an indicator light to show when your fuel pump is running?
 
TYCO W31 Internals

TYCO W31 Internals.

2yv7yhi.jpg
[/IMG]
 
Does anybody happen to have a cross-section photo of a typical "pullable" breaker like a Klixon 7277-series? Would be interesting to see the comparison. Lots of moving parts in the Tyco breaker/switch so it's easy to see where mechanical failure could lead to "no juice" to the aircraft systems.
 
Back
Top