Fuel gauges whacked

[Timcote1960]

Was flying my new bird N122wb home to DC from Boston with my wife. Beautiful WX, 2.5hr flight, 120gal aboard, burning about 10 each side according to the Shadins. Left with full fuel both gauges. By DE the needles were bouncing on zero.

I had to divert in DE to check it out. Of course, I'd only burnt 30gal. Wife was not happy, insisted she was about to die. She wasn't.

Still, it's not nice to have fuel gauges that say zero at 8,000'. What's the best solution?

Tim

[GearUp]

Cies with digital outputs: https://ciescorp.net/applications/sm...rcraft/cessna/
and your favorite glass engine monitor or a standalone from Aerospace Logic: http://www.aerospacelogic.com/index....category_id=70

[mshac]

When I was learning to fly, half the beater flight school 152s and 172s didn't have reliable fuel gauges, so I learned early on to visually inspect the fuel level before every flight, and when topping off, always check to make sure my estimated burn and the actual burn were in the same ballpark. We used a glass straw fuel level indicator that worked great on those planes. You could dip it and see exactly how many gallons you had.

When I was flying my Twin Bonanza, some guy had created a dipstick that went sideways into the tank to measure fuel. He sold lots of them to other Twin Bo owners.

Today with my Skymaster I always reset my JPI when I top off, and I use that to determine fuel on board. My analog gauges seem to work fine, but I still never use them as the primary information source.

[wslade2]

Ditto all.

I learned in planes that had gauges that were worthless or bounced so much essentially said nothing at all. My 182 has been that away all along, worthless. Once, on a trip from out west to the east, the cessna fuel gauges said I had a 1/4 tanks with a fuel truck "top off" at the last stop. We were in light the fires and go mode and left without dipping the tanks. But after a while pit of stomach didn't feel right. Landed and we were on fumes. Got reminded again to dip the tanks. So have never trusted those gauges and haven't looked at them for years. Gauges could give you a false sense of security. I added a fuel flow and dip the tanks, dip the tanks, dip the tanks.

I also don't fly down to "legal reserves" and always stop with excess fuel. (Wife says about to die if there isn't plenty of fuel.)

Just added a JPI engine monitor with fuel flow in my 337. 337 gauges have been beyond worthless from the getgo. Likewise reset the JPI at top off. But even with fuel flow, I still dip the tanks. (what if they are a little shy of full top off by teenage lineman? Experienced that more than once. You've entered "x" amount when really you have "y" amount.)

I have concocted a number of scenarios in my mind where fuel flow can mislead me and I don't rely on it entirely (for example recently had the fuel flow sensor run slow on rear engine and returned to normal after flushing it-must have had some sediment. Or what if a fuel leak somewhere.). Therefore would like some working gauges. Even so, at that point I will continue to dip the tanks. The perfect trifecta will be dipping the tanks, fuel flow and accurate gauges.

I keep a folding plastic step stool in the plane....so I can (you guessed it) dip the tanks. You can get clear dip tubes with markings from many sources. With regular use, you will get familiar with how much fuel you have at a given marking.

I plan on Cies probes and aerospace logic indicator when I can catch a break. (as I understand it will require removing upper wing panels and a project like that will certainly lead to surprises that will add time to install.)

[n86121]

Tim

Your gauges probably similar to mine.

"The technology that got man to the moon"
Scary, right?

The mains have two senders, and each aux has one sender.

They are all low resistance, so anything less than perfect contact and they jump.

Every few years I take mine out
and clean the wiper contacts w a touch of copper cleaner.
Good 'as new'

I have also found a way to modify custom orderable commercially available senders
that I have been thinking of trying.

Despite the allusion above, these are NOT rocket science.

MUCH better ways these days to get same measurements,
that will feed the same gauges but accurately and reliably.

Let's chat when you're bored.

Other option is/was Lockhaven airparts could/can overhaul each sender
(for around $200 ea?) if not smoked.

AND OF COURSE
On any trip of any length I always top off (plenty of payload available)
And rely on Shadin for the rest.

D

[TimJ]

Originally Posted by n86121

Tim

Other option is/was Lockhaven airparts could/can overhaul each sender
(for around $200 ea?) if not smoked.

D

I had them do 4 senders for me. took them just 3 days. Up until then I had never seen an older airplane with fuel gauges that didn't resemble windshield wipers. In addition after adjusting the gauges to the overhaul senders they actually pointed at the correct fuel amount.

[Kim Geyer]

Your plane should have capacitance probes and not resistance type probes. I usually fine a loose or corroded connection at the probe connection on top of the wing under the round panels. Then I would check the moles plugs in the leading edge of the wing at the fuselage. Should be the yellow and black wires
Kim

[TimJ]

Originally Posted by Kim Geyer

Your plane should have capacitance probes and not resistance type probes. I usually fine a loose or corroded connection at the probe connection on top of the wing under the round panels. Then I would check the moles plugs in the leading edge of the wing at the fuselage. Should be the yellow and black wires
Kim

My bad I should have been more specific. I am a part owner in a 78 baby Baron that has inter connected tanks that have two resistive senders per wing.

[Timcote1960]

Thanks for all the comments. Yes, I too trained in planes with bad gauges. And since my first preflight, on EVERY flight I look inside and dip the tanks. I KNEW these tanks were full at lift off; problem was there was a sudden dropoff along a flight. How does one know there is not a fuel leak unless one does what I did---land then refill? Having now done that with reassuring results, I have some comfort to fly whatever the gauges say. But otherwise, my hour's remaining flight in this new-to-me plane would have been pure hell imagining blue fuel streaming out behind me.....

My AP says there are 2 different sender systems on different models of the 337; the capacitive and the resistance type. He says mine are capacitive. Then there's "the box" that processes the sender's signals for output to the gauge. He's betting it's the box, which he claims has failed often before in his experience.

I'm not looking for perfection. But hopefully I will soon have gauges that do not throw my wife into the belief that her life is about to suddenly end.

To be continued.

Tim

[mshac]

Tim, are you based at Potomac?

[Timcote1960]

Yup. I fly out of KVKX with David W, also on this board also a 337 nut. He's not as crazy as me tho, as I own two of them. I used to live full-time in DC, then decided to do a 50/50 with a new business started in Cambridge MA. But it's turning into 80/20 MA/DC as the business is rocking and the wife is doing a masters at Tufts. So am I still out of KVKX? Sorta....

Tim

[mikes]

We have used the CESI ditigal senders on our 421B and C337G w/excellent results

[cartrm]

Originally Posted by mikes

We have used the CESI ditigal senders on our 421B and C337G w/excellent results

On your G, did you use two or four of the CIES senders?

[mikes]

I believe we used 4

[Dan schultz]

Tim

After I had the box overhauled mine worked fine.

Dan