Not Happy with Stearman Type Sight Gauge. Searching for Alternatives

[Ebby]

I have the Stearman style sight gauge that leaks. It is virtually identical to the ones manufactured by Yesteryear Aviation. I attempted to order a replacement tube with their upgraded O-ring and metal reinforcement at the bottom. No luck unless I wanted to pony up $550 for a complete unit. I’ve read other owners are using PA-12 sight gauges and I have one on order(4 - 6 week) lead time. Fingers crossed it comes sooner.

I did some research regarding fuel gauges and learned about electronic fuel senders. Has any builder had any experience adapting electronic fuel senders using the vacant hole left by the Stearman style sight gauge. It wouldn’t be period correct but fuel leaks take precedence.

I’m not opposed to fabricating a new leak-free tube for my existing gauge. In fact I came very close to success using ‘clear’ PVC pipe. It machines great on a lathe is clear enough to see the fuel bead and does not discolor with auto-gas. After two seasons it started to leak. If anyone knows of a plastic/resin/??? that would work please let me know. Yesteryear claims they are using the original material used by Boeing. I’ve searched but can’t find out what Boeing used.

[Dana]

Mine leaked, I replaced the o-rings, no more leaks.

Boeing probably used glass. I forget if mine was plastic or glass. Polycarbonate would be my choice for a replacement.

[HC85]

I am using the Piper fuel gauge assembly sold by Wag Aero or Univair. It was shorter in depth and required less modifications to get it to fit and function correctly. Good luck!

[Ebby]

I have an order in with Wag-Aero. Kevin at WA messaged me it’s 4-6 weeks out. I’m trying to modify the one I have so I don’t lose out on 6 weeks of flying. Glad to read the PA-12 does not need much modification.

[scsmith]

Boeing probably used glass. I forget if mine was plastic or glass. Polycarbonate would be my choice for a replacement.

Polycarbonate is NOT compatible with Avgas.

Ask anyone with an RV-12 about their rear windows (made of polycarbonate instead of acrylic for some reason, and the fuel tank filler neck is right next to the window, so you get occasional splashes of fuel on the window. It crazes and fogs.

[Ebby]

Problem solved for now. I fabricated a tube within a tube. Polycarbonate as the outer tube and glass inner tube. Nitrile seals and a pipe thread plug at the bottom. So far so good holding back the mogas.

[Dana]

Polycarbonate is NOT compatible with Avgas.

Ask anyone with an RV-12 about their rear windows (made of polycarbonate instead of acrylic for some reason, and the fuel tank filler neck is right next to the window, so you get occasional splashes of fuel on the window. It crazes and fogs.

Hmmm, data I've found indicates that PC is OK with both leaded and unleaded gasoline, but acrylic is not... though stressed plastics (like after bending or blowing a canopy) tends to be worse for chemical compatibility. I did make a homemade gascolator out of a PC block for my Kolb some years ago and it held up well. Regardless, glass is the best choice for chemical compatibility.

[mmarien]

I got plans from Michael R. Devroy for a sight gauge. I'm pretty sure they came from the Hatz group somehow but I can't find the source. He used acrylic tubing.

I got acrylic tubing off Amazon and added a fuel drain valve (a/s #05-01866) to the bottom of the tube. I'll post a version of mine when I finish it.

I attached his instructions and pictures.

Hey Hatz Nutz!

'Crazy' Mike here!

All that work!!!

I'm too cheap to buy the ACS ($30.00) or Wag-Aero ($66.00) gauges (indicators?), so made TWO DIFFERENT SETS(s) for my 'other' biplane - i.e. left & right wing tanks, for about $40.00!

Materials:

1.) SMALL O.D. version

- 1/2" O.D. acrylic tubing
- AN912 Bushing
- 1/4" allen head machine screw (w/ neoprene & stainless washer)
- Wine cork
- 1/8" aluminum TUBING (from hobby shop)
- 1/8" aluminum rivet(s)
- 1/8" countersunk aluminum pop rivet (w/ backing plate as washer)
- red rubber(?) 'thread' protector (for lower incicator), tested for fuel resistance, of course!
- 'Indianhead' sealant (for cork)

2.) LARGE O.D version

- 5/8" O.D. acrylic tubing
- AN911 Nipple
- AN910 Coupling
- AN913 Plug
- wine cork
- 1/8" aluminum TUBING (from hobby shop)
- 1/8" aluminum rivet(s)
- 1/8" countersunk aluminum pop rivet (w/ backing plate as washer)
- red Hobby 'Bead' (for lower incicator), tested for fuel resistance, of course!
- 'Indianhead' sealant (for cork)

* Threaded O.D. of the acrylic tubing to fit inside the Bushing (or Coupling & Nipple)
* Threaded I.D. of the opposite end of the acrylic tubing to fit the 1/4" machine screw (or AN913 Plug)
* Joined same
* Lubed/Sealed top w/ Clear Epoxy
* Lubed/Sealed bottom w/ Fuel Sealant (kinda like Pipe Dope)
* Placed aluminum rivet into ONE end of 1/8" aluminum tubing and WELDED end shut
* Drilled 1/8" hole thru center of cork
* Milled cork to Bushing (or Nipple) O.D.
* Slid cork onto open end of 1/8" aluminum tubing
* Using 'counter-sunk' aluminum backing plate & rivet, pop riveted top end of aluminum tubing to retain cork
* Epoxied thread protector (or Hobby Bead) to welded end of aluminum tubing
* Coated cork with Sealant

Further assembly will hopefully be self explanitory.

I have installed and flown with the SMALL O.D. version, and have yet to see the first indication of a fuel leak.

I built the LARGE O.D. set in the event the SMALL O.D. should 'inadvertantly' get snapped off! In addition, I carry a AN913 Plug to plug the tank should I need an EMERGENCY Field Repair!

On a related note, my Wag-Aero (simple) Vented Fuel Caps had a tendency to vent fuel... (1 gallon in 45 minutes!!!)

NAPA sells a BEAUTIFUL!!! Chrome Plated, Vented - i.e. via CHECK VALVE, fuel cap for about $6.50!!! Part Number 733-1220!!!

Works Great, Lasts a long time!

Hope this helps,

'Til next time,

Happy Landings!

CM

Michael R. Devroy
W1257 Luscome Lane
Lake Geneva, WI 53147
C: 847-224-5192
H: 262-248-4190
mdevroy@earthlink.net

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