kwlf wrote:
I suspect the time will come when every aircraft needs an electrical system… At which point an electric pump would become a worthwhile addition.
This is what we have been doing the last week ends:
Mounting EFI on the tow plane (Rotax 912 with “big bore”). A much bigger job than anyone suspected, but it looks real cool, and a very nice kit. I’m sure the engine will run much better than the default setup with two carbs, and will be easy to start, but more reliable? I’m not so sure actually. There is the usual twin pump setup, but if the battery runs down, the engine stops. I don’t think it will be worse than before, but it won’t be better either (but it could be with some simple addition).
Personally I would have changed the electrical system also. Put in some galvanic isolation and backup battery for the ECU and pump, so it would be isolated from all the other stuff and could run even if the main battery or the backup battery should run flat. Maybe also a secondary ECU for backup, but I’m not really sure if the added redundancy of that really makes up for the added complexity. I would have replaced the default Rotax voltage regulator also.
With these, and similar things, it’s always nice to remember Einstein’s famous quote: “Make things as simple as possible, but not simpler”, although I doubt Einstein had fuel systems in mind when making that quote 
kwlf wrote:
It’s not that I value authenticity over reliability, but often I’m not convinced that newer parts for old cars are particularly well made
That’s true for newer aircraft parts too – Slick mags versus Bendix being another good example, and new mechanical instruments like tachometers being a complete disaster. What I tend to do (FWIW) is not worry about it too much for parts that I’ll be throwing away anyway after a while: the practical way to ensure reliability of a fuel system or mags is to replace components every 5-10 years or so. Despite being relatively poorly made in 2017, and typically impossible to overhaul, they last long enough. For other more permanent stuff like tailwheel assemblies, I’ve instead overhauled the old unit at considerable expense: an overhauled but no longer available new Scott 2000 is worlds better than a new Maule tailwheel and won’t be later thrown away as part of normal maintenance.
kwlf wrote:
At the very least I would like to have 1 battery to rule them all
Technically, that was of course the traditional approach. I am not sure it is still viable with today’s battery technology. And I’d much prefer to have the battery of one ancillary to give out over loosing the one that powers all of them.
But I much appreciate the reference to Master JRRT!
Low winger… But with a fuel tank above your legs.
I’m afraid I disagree re. batteries. They’re certainly much better than they used to be, but still very capable of running out. At the very least I would like to have 1 battery to rule them all – radio, pump, headset, gps, transponder…
You asked why I didn’t get my location from my gps..? The answer is that the internal battery only lasts an hour and the external battery switching regulator interferes with the radio. A work in progress… Mid Wales is blissfully easy to navigate provided you keep clear of the Mach loop, but you’re right in that it would have been helpful in the emergency.
kwlf wrote:
I suspect the time will come when every aircraft needs an electrical system
Sorry to disagree. More and more appliances and accessories can be run from batteries, thanks to the hefty progress in battery technology. I even observe a tendency among gliders to replace FLARM by a proper transponder (but no side-discussions please, flarm has already been discussed to death). There is less reason than ever to have a traditional electrical system in simple planes.
kwlf wrote:
an electric pump would become a worthwhile addition
For your low (or mid?)-winger, yes, perhaps. My own pride and beauty carries fuel in her high wing, gravity does the job of feeding fuel quite nicely. No need to add complexity/potential failure.
Thanks, that’s interesting. I don’t think it would be entirely simple to install an updraft carb as the magnetos are under the engine, but I can see the advantages of the system.
I suspect the time will come when every aircraft needs an electrical system… At which point an electric pump would become a worthwhile addition.
kwlf wrote:
If the problem was clearly with a gasket, why would I replace the whole pump?
For VW aircraft engines, the norm today seems to be to get rid of the pump altogether, by changing the setup to updraft (the carb below the engine), and using gravity feed. I’m guessing this can be done on the turbulent as well? I have heard even Sauer and Limbach have problems getting reliable fuel pumps (I have no idea if it’s a gasket problem though). The normal setting with an engine driven pump, is also to have an electric backup pump (but this won’t solve the gasket problem either).
I agree there is no need to change the whole pump, I just don’t think the setup itself is the best.
It’s been done… Every control surface off, every instrument out and back in again…
It’s not that I value authenticity over reliability, but often I’m not convinced that newer parts for old cars are particularly well made. E.g. Vw cylinder heads have a better reputation than newly manufactured ones; I’ve just bought a carb refurbishment kit which looks as if it was made by an enthusiast in a shed. The gaskets are good but the accelerator pump diaphragm was shoddy. If the problem was clearly with a gasket, why would I replace the whole pump?
There are no special laws about selling aircraft as far as I know. An aircraft is just a heap of materials that may or may not function in unison. But, the law is very clear on who is responsible for keeping the aircraft airworthy, that is the owner. Then, to fly the aircraft, the PIC is responsible to check (within his capability) that the aircraft is airworthy and in order for the mission. It couldn’t be simpler.
This is a 50+ ? year old homebuilt with largely unknown history ? The only way to make sure it’s airworthy is to strip it down in all it’s pieces, replace and fix as needed, then put it together again, IMO. I do find it a bit odd you prefer “old looks” over reliability though
surely an aircraft seller is morally if not legally responsible for being forthcoming about any issues or incidents in the past.
A good thread is here
This issue will never go away, because why should humans behave any differently when selling a plane compared with selling a car or a house?
That’s why one needs to do a good prebuy, but in this case the fault could not have been picked up by inspection. Only knowledge of the type, and that there are cork gaskets in the fuel system after any filter, would have helped. I would replace that gasket with a rubber one. I think that is the normal solution. The TB20 (and any fuel injected aircraft) has a similar vulnerability via the two gaskets at the two ends of the fuel servo; one is made of high quality rubber and the other is some sort of fibre but is very thin and both are well clamped between two metal surfaces. And it is much easier to block the fuel than to block the air.
Another thing is that one should always replace seals (with new ones) when reassembling. This was the cause of a pretty significant oil leak I had on the exterior of my engine, recently. I re-seated a pushrod shroud tube without replacing the £2 seal at the base of it. With a cork seal, this is especially important. And using cork in the fuel system is crazy because that’s what cork does – little bits come off.
