Fuel Guages

[Carl Thuringer]

I am really glad to have worked out the ownership of a wonderful Twin Comanche. I am trying to figure out the fuel gauges, when I select the aux tanks the gauges do not change. I have a feeling this has to do with the selection unit but am very new to this. Any suggestions for checking the selectors, I am under the assumption that this is some sort of a contact system.

[bernard nowlen]

There are micro switches in the fuel control valves that are switched by little "buttons" in the valve selector plate when you switch the tanks. They are actually pushed down by the fuel selector arm(on top of the valve) when you reposition it and the source for the fuel quantity gage goes from main to aux and vice versa.bernie

[Carl Thuringer]

Thank you Bernie, I will check that out his weekend!

[N3322G]

Carl,

Welcome to Twin Comanche flying - they are great planes.

As a new owner, hopefully you had a great pre-buy and a qualified instructor to give you some dual. Even with 44 years around our Twin and sole ownership for 18 years, I find there is always something to learn and regularly take Comanche courses.

I suggest these guys http://www.comanchetraining.com/

BTW if aux and mains are both full, there would be little to no change in gauges.

Hope this helps

[Carl Thuringer]

Thank you very much or the training suggestion!!!! We picked up the bird in Arizona after an extensive pre-buy. When I am burning the mains the right gauge stays in the full reading, upon visual inspection it is very evident that the fuel level is down the same amount as the left. The left works just fine.

[N3322G]

Hi Carl,

Ah fuel gauges - let me count the ways they are 'fun'.

It is my understanding that they are required to show when the tank is empty ... not necessarily reflect how full the tank may be

My Twin is a 39 and a 1970 so there may be differences - by dint of reading the online maintenance manual sections I need at the time (I finally bought a printed one via this Forums) http://www.comancheflyer.com/NS/index_serv_manuals.php I have learned a lot ... that and checkbook tutorials, I know the fuel level sensors in the tanks can be O/H by Air Parts of Lock Haven http://www.airpartsoflockhaven.com/ and then they have to be correctly re-installed and adjusted with good wiring and grounds in order to work well.

I have had all of the above work done at one time or another. What we rely on is visual pre-flight inspection for full tanks, shadin fuel computer and always, manual calculations so we know where the fuel is.

Lots of questions have been asked about fuel stuff on the Forums so I put together a description of the pre-flight we use. viewtopic.php?f=86&t=7569&p=59642&hilit=fuel+hygiene#p59642
Perhaps it may help you.

By the way, you are relatively close to a really good Comanche shop at KRFD, Heritage Aero. If you want the work on your Twin with a high degree of confidence, done correctly, I suggest Cliff and his crew. They may be others in your area, I just don't know them.

Also, keep an eye out for Kirstin Winter. She's a West coast woman now but formerly of MN so she gets back that way - she's got all the A's. A&P/IA, ATP, Aviation Attorney plus her own Twin and a mellow but precise CFI style.

Be sure to go to the ICS tent at OSH this year - even if you drive over - you will learn a ton from other owners and the tent sessions and the CTPT folks are running a session there.