There’s so much that can go wrong, mixture or not (putting aside turbines).
Gasoline may not ignite at all in compression-ignition engines (diesel), and it’s very possible that Jet-A1 does not ignite with sparks either, or ignites too early, or too slowly etc.
Not even counting the fuel system (I’m pretty sure diesel fuel can quickly clog gasoline filters and gasoline can create vapor locks where Jet would not). The default behavior to expect is that the engine just stops completely (or breaks). This has happened is many accidents for both misfuel ways.
But if the misfuel is identified before takeoff (or before the engine is damaged), I don’t think a new tank is in order. A proper drain, clean and inspection / replacement of various filters and pumps should be well enough (just like when there’s a fuel contamination). It’s no small task, but I don’t think it requires a new tank.
UdoR wrote:
how long would it take after switching tanks until there’s combustible fuel available from a different tank?
I think this is heavily fuel-system dependent (electric pump, gravity, etc.)
But the starvation is another problem entirely. If you select an empty tank before takeoff (or close the selector), you can very much expect to lose all power suddenly during late takeoff / initial climb. The fuel in the line (which most probably depletes slower than the time it takes to fill an empty line with fuel) is in the range of minutes. The same could theoretically happen on empty tanks (but tanks are almost never empty so this is more likely going to take longer).
Given a Lycoming without tank return line, how long would it take after switching tanks until there’s combustible fuel available from a different tank?
As a safety measure, I typically do not refuel all tanks at other airfields and do the takeoff on that tank that was most filled before going to the pump station. So in principle I should be quite safe from the engine starvation problem very low above ground. However, has anyone experience on how long it takes?
From my side, I once forgot to switch tanks, the engine RPM fell, I turned on aux pump immediately, switched tanks, and after about 5 seconds (and about 200 feet altitude lost, that would have been avoidable if I would have watched my altitude) the engine had power and some more seconds more (maybe another 5) it was running pefectly smooth again. Would this be any different with other fuel like Jet fuel in the fuel line?
This is an interesting article on this topic.
It is not what most people thought!
You can have a mixture of 100LL and jet-A1 and the preflight runup checks may be ok, and the engine destroys itself when you go to full power for takeoff. Mike Bush states
The real-world problem is not running on pure Jet A, but on running on a mixture of 100LL and Jet A. Depending on the mixture ratio of the two fuels, the effective octane rating can be anything between zero and 100. A mixture with a lot of Jet A and just a little 100LL might be detectable during runup. A 50/50 mix might not start to detonate until full power is applied, and the engine might fail catastrophically 30 seconds or 3 minutes after takeoff. Just a little Jet A contamination might produce only moderate detonation that might eventually cause spark plug nose core insulators to crack or might not be noticeable at all. Like so many other things in aviation, it all depends.
so you could do a normal refuel, say starting with half empty tanks, with jet-A1 instead of avgas, and still pass the preflight. Well, that is what is claimed.
Garrett’s can also run Avgas or Mogas for a certain amounts of time. Think it’s 100hrs per 1000hr interval or something. I’ll have to look my POH up.
f I had a Merdian …
sorry, my mistake. I meant MALIBU …
If I had a Merdian or a I’d never leave the plane alone at refuelling, and Cirrus with the word “turbo”
A Meridian can run on avgas perfectly fine. It is the piston versions that stop if filled with Jet-A1. Witness the recent Mirage accident at the home of Jetprop.
Turbine engines burn almost anything.
Flyer59 wrote:
If I had a Merdian or a I’d never leave the plane alone at refuelling
Anyone flying a DA40 should be very careful about what is poured into their tanks. I have had the fuel bowser with Jet-A1 pull up to me after having asked tower for fuel, although the aircraft I was flying was powered by a Lyco IO360. In Europe people are used to DA40s being powered by diesel engines. I do not know about any DA42 with IO360s flying around in Europe, so chances are that the Jet-A1 truck will turn up, but had I been flying a DA42TDI in the US I would have been equally careful.
, and Cirrus with the word “turbo” … I’d remove that if I lived in the USA and let line boys do the refueling. Also a BIG RED DECAL “AVGAS” can help
In the US the Avgas decal is not red. And I was more or less forced to replace a US Avgas decal by one of those red ones with white letters in order to get served in France once. Others have reported similar experiences.
Those decals (red for avgas and black for Jet-A1) are a very good idea, especially for aircraft using “unusual” fuels.
A Diesel engine is yet another case than a piston gasoline engine. I guess a Diesel will run if the amount of Avgas is not too big.
From an article on AvWeb:
On March 2, 2008, a turbonormalized Cirrus SR22 was destroyed when it crashed shortly after takeoff in Rio de Janeiro, Brazil, killing all four people aboard. Shortly after the aircraft departed from Runway 20, the airplane’s engine lost power, and the aircraft hit a building and exploded. Further investigation revealed that the aircraft had been refueled with Jet A instead of 100LL.
The mixing question has already been answered in this very thread.
A friend filled DA40 TDI with gasoline. He was able to fly for an hour or so before it quit. Luckily he landed safely. Engine had to be sent to Thielert for inspection afterwards.
