Sight gauges

coloradobluesky

coloradobluesky

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coloradobluesky
Sight gauges are terrific because you are looking at your actual fuel. But they arent perfect. One problem is they read the same with FULL fuel and EMPTY. No fuel demarkation on the sight guage in both cases. USUALLY not a problem, but if your plane leaks almost all of its fuel and you arent aware of it, and you think you have full fuel because that is the way you put it away, you might misread empty for full. Be careful out there....
 
The Husky uses a flexible plastic tube for fuel sight gauges. A year ago I found the tubes in one airplane cracking from the inside of the tubing. Scary, considering that a tube failure could dump vast quantities of gasoline into the cockpit.

A thing to watch for at annuals. Shine a light on them and look for anything unusual. The light will show the internal cracks as fine lines perpendicular to the tube axis.
 
The 162 has the sight gauges but even with the tanks topped off you can see the fuel line at the top of the gauge.
 
The sight gauge in my plane has an orange ball floating in it, no way to miss it.
 
The PA12 sight gauge has a float of some color so you can see it.
 
coloradobluesky said:
Sight gauges are terrific because you are looking at your actual fuel. But they arent perfect. One problem is they read the same with FULL fuel and EMPTY. No fuel demarkation on the sight guage in both cases. USUALLY not a problem, but if your plane leaks almost all of its fuel and you arent aware of it, and you think you have full fuel because that is the way you put it away, you might misread empty for full. Be careful out there....
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What ??

The little orange ball should never go out of sight.
 
The Yankee I had didn't have an orange ball, it was black. ;) But still easy to see, against the light colored background.
 
Tom-D said:
What ??

The little orange ball should never go out of sight.
Click to expand...
Yeah, not following either. There are lots of different sight gauges. Some have floats with a little bobber (like my Waco) others have a little ball inside the gauge like the Citation. At least on all the aircraft sight gauges I've ever seen.
 
A float in the sight gauge is required for standard aircraft nowadays, but that wasn't always the case. Older aircraft may not have them. I believe the requirement came in sometime in the 1980s... I remember talking to Dorothy Ferris (owner of Taylorcraft Corporation at the time) about the new requirement and the trouble she was having sourcing the balls.
 
This was one of the issues with the John Denver crash. The aircraft had sight gauges that were non-linear (and if I recall unmarked).

Unmarked doesn't pass the current certification standards (not that the markings mean much).
 
Some don't have the floats. None of the Huskies Ive seen have them. Ive flown some other models but dont remember. I ll take your word that the others have them. Could be true. But probably not ALL....
 
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