128 by fuel starvation
93 by fuel exhaustion
What is the difference?
I guess “starvation” could be
128 in Cessna twins then?
Hmmm yes “starvation” could be no fuel to the engine but fuel still carried on the aircraft. That could be SE or ME, except that the dodgy fuel systems tend to be in MEs.
This fuel sender signal conditioner (from some twin) may also be a reason for getting the fuel wrong. It costs about 20k to replace with one that comes with an EASA-1 form.
I think that the Cessna twin scenario is more often caused by mismanagement of a Byzantine system than a failed quantity indicator.
Whoever goes by fuel gauges in 40 year old aircraft, needs to watch out. They’re useless. They need to keep track of usage, either the old fashioned way, or by using a totalizer.
That said, on the Aerostar, they were correct down to the gallon. I could see if the plane wasn’t flying level just by looking at the two wing tank gauges – that’s how accurate they were.
Peter wrote:
128 by fuel starvation
93 by fuel exhaustionWhat is the difference?
Simple. At least in US parlance:
starvation = fuel doesn’t get to the engine(s) for whatever reason, e.g. mismanagement (more likely on piston twins, as Timothy mentions), blockage, etc
exhaustion = no fuel left on board
AdamFrisch wrote:
Whoever goes by fuel gauges in 40 year old aircraft, needs to watch out. They’re useless.
Let’s make that “Whoever goes by fuel gauges … needs to watch out.” Even on brand new SEP aircraft! The only accurate indication is the E for Empty.
Once you go SET it gets a bit better. I.e. the Cessna Caravan has the same type sensor, but four of them per tank, leading to an average reading on the gauge.
Or on planes with capacitive fuel senders such as those from CIES on newer Cirrus models. Those are pretty accurate.
The TB20GT also has capacitive sensors which are accurate to the thickness of the needle – probably would be within 2-3% if the gauge had markings on it other than colour bands 
The problem is that while one operates a car by the fuel gauge, stopping for fuel when it gets low, a flight is planned for fuel and during flight you monitor the fuel burn versus progress along the route. For this continuous monitoring to work you need either finely graduated and accurate gauges, or a GPS-linked totaliser. In the old days (crap gauges and no totaliser) you assumed a certain fuel burn and you monitored progress by the time of arrival at waypoints (hence the old plog forms which had loads of columns for time and calculated fuel at each waypoint etc) which worked if the fuel burn was accurately known.
In reality almost nobody does any the above methods. In the GA scene most people say to themselves “I have 4hrs in the tanks so I can fly for 3hrs”. That is how one is trained in the PPL. It is an obvious recipe for running out as soon as something slightly unexpected happens. Even most pilots who have a totaliser don’t use it. Socata shipped several hundred TBs with the totaliser reading some 25% out (due to the transducer being mounted in the wrong place) and almost nobody noticed.
What really surprised me in that survey is how large a % are fuel related. Yes fuel planning is taught so badly in the PPL, and even if it was taught well it would be hard to execute because it is almost impossible to accurately run any of the along the route fuel monitoring methods.
The only accurate indication is the E for Empty.
Actually you still have a few gallons useable when the sight gauges in the wing roots of the Piper Super Cub show E.
