Flight Strobe FS-4400

[mmcmillan2]

My strobe is no longer strobing reliably. It flashes maybe 5 times per minute now. It appears to still be for sale on Aircraft Spruce, but I want to troubleshoot first.

Can I assume the bulb is probably fine if it flashes occasionally?

I’m going to look inside the unit to see if the connections are clean and the capacitors haven’t blown. Best way to discharge the capacitor so I don’t get shocked?

Also, what is this secondary unit I have installed inline with the power wire? I think it says Sprague HYBASS 40amps. I’m thinking maybe it is a filter or something the previous owner added to reduce the strobe noise in the headsets. You can still hear the strobe noise.

Thanks!

IMG_5512.jpeg

[mmcmillan2]

IMG_5515.jpeg

[RobfromME]

Good afternoon!

The Sprague is actually HYPASS.. it's a noise filter. I had that same strobe and when it was working it was noisy, and then was intermittent. It's not a particularly good strobe. Although more expensive, I replaced mine with a Whelen LED beacon....less power, brighter, lighter, and no noise. I'd never go back to a flash tube strobe.
Gallagher currently has them for $30 less than what I paid last July. Right now they are ~$640.
https://www.gallagheraviationllc.com/WA ... p_181.html

[mmcmillan2]

Thanks for the reply. I’m thinking maybe the LED replacement is what I should do.

[n2582d]

Mark,
First, I'd agree that an LED replacement is probably the way to go. The manufacturer's www.universal-co.com website appear to be defunct so one wonders how much longer parts will be available. Looking at the "factory" address on Google Maps shows a farmhouse northeast of Cleveland. My guess is the owner retired. Reviews on A/C Spruce of the unit are mixed. One guy says, "Do not buy this unit, the bulb that comes with has constant problems, I have been using it for three or four years and had to change the bulbs several times because of the solder coming loose on the housing or is burning out prematurely. You may save some money buying this unit but you will spend a lot more in the long run on bulbs." That being said, it's easy spending someone else's money. To fix the unit I'd try bypassing the noise filter. These filters are cheap online but I don't know how reliable a filter that's been on a shelf for 30 years is going to be. Check out this "vintage" filter. Might be worth asking an avionics tech for noise filter recommendations. If the filter is not the problem, I'd check the unit for internal corrosion. The Installation Instructions posted on the A/C Spruce website say, "do not attempt to loosen the inner screws on the bottom of the strobe. This could cause intermittent operation." Any chance those two screw are loose or corroded? The directions also answer your question about avoiding getting shocked: "Before changing flash tubes short lamp leads together to avoid possible shock."

Regardless of whether you fix the FS-4400 or buy a new LED unit, you might take a look at AC43.13-2B chapter 4 "Anticollision and Supplementary Light Installation". There really should be a doubler around the unit instead of just being mounted with four or five tinnerman screws. And those wires snaking around the rudder cables scare me. On the other hand, if the strobe was installed by an A&P and approved by the FAA with a field approval, and it hasn't "broke" in 30 years, why fix it?

[mmcmillan2]

Removed and found the unit bench tested good. Reinstalled and had sluggish performance again. Removed that filter, and voila. Thanks guys.

FYI, the mfg website does work and they responded to my email quickly.

http://universal-co.com/universal_005.htm