Fuel Quantity Indicators

[Fly_Chick]

I seem to remember hearing that (on single-engine piston airplanes) that the fuel gauges, per the regulations, need to only read accurately when the tanks are empty.

I cannot find the reg on this. Anyone hear of this or know which reg?

 

[Fly_Chick]

I think I found it, FAR 23.1337(b).

 

[Vik]

That is true. Also, the indicators have to work the fuel selector is turned to the off position. The wiring in my plane was screwed up at some point and when we turned the fuel to "OFF" it would read "FULL" which wasn't legal either. Same thing as what you've said below but a different scenario.

I seem to remember hearing that (on single-engine piston airplanes) that the fuel gauges, per the regulations, need to only read accurately when the tanks are empty.

I cannot find the reg on this. Anyone hear of this or know which reg?

 

[JAFI]

Be careful here. There is a certification standard yes. However if the aircraft maintenance manual has a fuel guage standard that might be the required standard not the certification standard. The certification standard is to get approved for Part 23/25 or in the past CAR. If the maintenance manual has a calabration requirement, that could be the required check. I say "could be" because I am not an A&P much less an IA. But I do get to read a few manuals and deal with a reg or two. You may want to look at the maintenance manual.


JAFI

 

[avbug]

To expand a little on what JAFI set forth, the airworthiness standards for any aircraft are the approved data applicable to that aircraft. Approved data means any relevant sources of data that are approved by the Administrator. This includes the regulations under which the aircraft is certificated applicable to it's type certificate, Airworthiness Directives, Supplemental Type Certificates, Field Approvals, and any approved aircraft or component manufacturer maintenance publications.

You should also remember that while the aircraft manufacturer may not have any detailed information on the calibration of the instrument, the instrument manufacturer may.

It's true that in general the only time the instrument is required to be accurate is when empty. However, if that aircraft left the factory with the equipment installed and accurate at all levels, then it had better be the same; it must meet it's type design requirements, and that isn't only what is spelled out in the regulations for type certification. For example, the type certification requirements may not require a given light or antenna, but if installed at the factory, it must be operable per it's installed condition and any relevant approved data, or altered in a manner acceptable to the Administrator.