Shrike Accident, Hollywood FL

[schrambow]

my experience with the commanders are that the fuel gauges and levels are very accurate compared to a lot of other aircraft. The main tank on the 680FLP are eerie accurate to within 50 lbs i think, and the turbos are the same on their tanks and their indicators.(the outboard tanks on the 681 weren't very accurate, but it was a different type of indication system) But i guess we did calibrate them awhile back to verify the levels, plus operating the same plane for many years one gets to know the quirks and other stuff like that in a plane like the back of your hand. 
Other planes like Ercoupes, Cessnas, Pipers, Bellancas, and many others i think are far less accurate in the fuel indications than the Commanders, but then maybe we spent more maintenance and money to make sure they are accurate for longer trips and such.

[donv]

It's been way too long for me to remember what the issues are with the Shrike fuel gauging-- Bruce probably could tell us. The Jetprop gauges are fantastic, and the 690, as I recall, reads full down to about 2500 pounds, then drops to 1200 pounds and sits there for a long time, and then starts reading accurately.

As I recall the 690 gauges are only supposed to be accurate at full and close to empty.

[SKYFLYER]

The FAA only requires the gauges to be accurate at EMPTY for certification

[Bruce Byerly]

The FAA only requires the gauges to be accurate at EMPTY for certification

No way that’s true

[SKYFLYER]

The Regulations Do Not Say that the Fuel Gauge Must be Accurate "Only When Reading Zero"

Perhaps you might want to read the regs

https://www.aviationlawmonitor.com/2011/06/general-aviation/aircraft-fuel-gauges-are-supposed-to-actually-work/

https://www.govinfo.gov/content/pkg/CFR-2009-title14-vol1/pdf/CFR-2009-title14-vol1-sec23-1337.pdf

[Adam Frisch]

My Aerostar had the most accurate fuel gauges of any aircraft I'd owned. I could see in the gauges when I was flying out of trim quicker than on the ball. Unreal.

As I recall it, you can change the floaters to capacitance ones and get much better accuracy for the Commanders. As a side, and don't ask me how I know this , but the low fuel warning light on the 680V is damn accurate. Light comes on when there's about 50gal left. So, even if the gauges crap out on me, I can always rely on that light to give me a fair warning.

[Bruce Byerly]

The Regulations Do Not Say that the Fuel Gauge Must be Accurate "Only When Reading Zero"

Perhaps you might want to read the regs

https://www.aviationlawmonitor.com/2011/06/general-aviation/aircraft-fuel-gauges-are-supposed-to-actually-work/

https://www.govinfo.gov/content/pkg/CFR-2009-title14-vol1/pdf/CFR-2009-title14-vol1-sec23-1337.pdf

Fuel quantity indication. There
must be a means to indicate to the
flightcrew members the quantity of us-
able fuel in each tank during flight. An
indicator calibrated in appropriate
units and clearly marked to indicate
those units must be used. In addition:
(1) Each fuel quantity indicator must
be calibrated to read ‘‘zero’’ during
level flight when the quantity of fuel
remaining in the tank is equal to the
unusable fuel supply determined under
§ 23.959(a);
(2) Each exposed sight gauge used as
a fuel quantity indicator must be pro-
tected against damage;
(3) Each sight gauge that forms a
trap in which water can collect Andy
freeze must have means to allow drain-
age on the ground;
(4) There must be a means to indicate
the amount of usable fuel in each tank
when the airplane is on the ground ....

You’re saying the above verbiage is equal to “The FAA only requires the gauges to be accurate at EMPTY for certification?”  I don’t think that’s how the FAA sees the spirit of the rule, but anyway.

[donv]

Actually, that's exactly what it says.

23.1337(b)(1) says exactly that.

To be honest, I don't know if the 500 series was even certificated under part 23 (could have been the previous regulation).

Whether that's the spirit of the rule, I don't know, but that is what it says.

Bruce, what is your lived experience with 500 fuel gauges?

The Regulations Do Not Say that the Fuel Gauge Must be Accurate "Only When Reading Zero"

Perhaps you might want to read the regs

https://www.aviationlawmonitor.com/2011/06/general-aviation/aircraft-fuel-gauges-are-supposed-to-actually-work/

https://www.govinfo.gov/content/pkg/CFR-2009-title14-vol1/pdf/CFR-2009-title14-vol1-sec23-1337.pdf

[Bruce Byerly]

The Single gauge in a 500 should work.  But when it quits it can read mid range which has caused a few problems. Also going downhill it will read low which is unnerving on approach. And it doesn’t read above 135-136 or so so you have to check or you WILL get shorted the 5 or more gallons every time.

[donv]

Thanks-- that makes sense.