Three valve fuel system hazard.

[nong]

I was asked to take a 19- reg. home assembled J230 for a post maintenance test run. Accompanied by the L2 concerned, we taxied out and blasted off.

 

Eight minutes into the flight the donk surged a couple of times then stopped. Thirty seconds later we coasted to a halt in a tranquil rural scene. It was obvious to both of us that juice wasn't getting to where it was meant to be.

 

My mate pulled out some tools and started pulling things apart to track down the problem.

 

At some point I remembered a Jabiru employee telling me that they used a single valve on factory assembled aircraft because it was reckoned to be the safest set-up.

 

A peek under the dangling shoulder straps revealed a valve on each downpipe. The valves had short actuating arms that were fully hidden by the straps. Of course, they were in the OFF position.

 

When asked about the set up, the owner explained that it was good because it enabled him to park on a transverse slope. Fair enough, it's his aircraft.

 

Personally, I reckon these should be regarded as MAINTENANCE VALVES and be safety wired in the OPEN position.

 

As for a fuel system that, with the tanks shut off, would allow about 1.5 km of taxying, run-up and checks, followed by eight minutes of flight at take-off and cruise power..... That's crummy!

 

I am becoming very wary of 19- reg aircraft! Wary, but not bitter! Builder freedom...driver beware.

 

My J160C won't go a hundred metres with the (single) fuel valve turned OFF. Good design, better safety.

 

 

[jetjr]

these valves are supposed to be labelled 'not for use in flight' and are deleted on new models. supposed to have handles removed as they can cause untested out of balance situation if just one side is drained in flight

 

they should form part of the pre flight checks if installed

 

jabiru also offer a low fuel light in the header tank which Would have lit if fitted

 

I agree they are agood thing to have but must be understood and checked. If I turn these off I always turn the main tap off also as a reminder

 

 

[Jaba-who]

These were standard in all Jabs until fairly recently so it wasn't your particular home builders own add-ons. I have them in mine which was a kit purchased in 2006. (though I also have a header tank low level warning light and a "check all fuel taps open" on my preflight checklist on the Dynon which I use religiously ). The long duration of flying till they cut out is due to the header tank having 6 litres of fuel and the header tank is AFTER the wing taps. There was a Jab crashed just south of Cooktown a few years ago due to the same problem.

 

In one of the very first test phase flights I did the same thing but with less dramatic results. Luckily my engine started to surge and splutter first. I had a co-pilot for that flight (checking numbers for me) and he asked about fuel , which made me remember the taps. Turned them and pretty much straight away it started running smooth again. - in my case it showed up two problems -

 

1. I needed the "Check taps" in my checklist

 

2. My Dynon did not have the warning setting enabled on the header tank.

 

Trouble is if you don't have them the tanks cross feed when standing on a slope. I also have made use of them when doing maintenance and I wanted to drain one tank.

 

Also had a time when a fuel cap came out on a long leg (Coober pedy to Streaky Bay) although the only indication I had of a problem was that tank was running dry at too fast rate. Was not sure what was going on so could at least isolate the tank. I am not sure if it would have sucked the other tank dry but it might have if the venturi effect at the open tank was enough. My other concern was I might have sprung a leak in a line somewhere and could be filling the fuselage up with fuel although we couldn't smell anything, so I really was happier with the tank isolated and off.

 

Guess its a good argument for not flying anything unless you are familiar with the fuel system in that aircraft.

 

 

[David Isaac]

What happened to the concept of the good old single 4 way valve such as used by Cessna and Piper ... "Both, Left,Right, Off". Much less prone to error.

 

 

[turboplanner]

Steady on David, we don't actually want safe systems, or to have to do any pre-flight checking these days.

 

 

[Tomo]

I reckon these should be regarded as MAINTENANCE VALVES and be safety wired in the OPEN position.As for a fuel system that, with the tanks shut off, would allow about 1.5 km of taxying, run-up and checks, followed by eight minutes of flight at take-off and cruise power..... That's crummy!

You have a point about the three valves, if you only thought it had the one tap you wouldn't bother checking anywhere else... but in my opinion a good knowledge of the fuel system in each aircraft is paramount before leaving the ground. I'm surprised the owner didn't say anything to you about it!!!

 

I must say 8 mins of flight time is better than 2 min or so, when you're 50' on take off.

 

I wouldn't say having the the two wing taps were a bad idea, infact I think it is a good thing for parking on unlevel ground, just needs to be added to the checklist.

 

 

[David Isaac]

To solve the unlevel ground problem in a Cessna or Piper all you need do is pick any position other than "both" on the single 4 way valve. But why make it simple when you can complicate it ... LOL

 

 

[Tomo]

To solve the unlevel ground problem in a Cessna or Piper all you need do is pick any position other than "both" on the single 4 way valve. But why make it simple when you can complicate it ... LOL

True, but there are many aircraft that don't have that system, I don't know why but that's just the way it goes. The Left/Right tank only positions such as Piper and other Cessna's etc... aren't a real good idea. But it's okay as we use fuel management in our flying... though it certainly isn't a fool proof system.

 

 

[dazza 38]

Interesting The C172 fuel system.In the latest Crash comick , there is a story of where the handle was thought to be on the both setting, but was actually in the off setting.EFATO happened.

 

 

[biggles]

My pre take-off check list states ....................... " Fuel cocks ( 3 off ) - OPEN "

 

Bob

 

 

[biggles]

Oh dear , I have been ' Censored ' . The above post should have read ............ " Fuel c ---s . Please substitute another term " - Fuel valves

 

 

Sorry Ian

 

Bob:oops:

 

 

[Jaba-who]

The Left/Right tank only positions such as Piper and other Cessna's etc... aren't a real good idea. But it's okay as we use fuel management in our flying... though it certainly isn't a fool proof system.

Yeah. I was in a piper warrior once, heading for normanton from Cairns (as passenger so can absolve myself of this one) with fuel tap setting on left tank. We were talking, in company with other aircraft, distracted from fuel log. (I was used to taps on Both ) I can tell you that one tank on a warrior gets you to 40 nm from Normanton and then it goes very quiet very quick

 

 

[dazza 38]

Oh dear , I have been ' Censored ' . The above post should have read ............ " Fuel c ---s . Please substitute another term " - Fuel valves Sorry Ian

 

Bob:oops:

Thats normal Bob. I have typed that many of times.I use "tap" , instead.Its normal swearing software I think.

 

 

[jetjr]

Id reckon the 4 way taps like in Piper etc are horrendously expensive and require much better design of not only fuel supply but venting too. In a gravity setup this can cause plenty of problems

 

The overall message here is know about the aircraft you are flying, get checked out by the owner first, use aircraft specific checklists. Any tap for capable of stopping fuel should be high on priority list when flying a new aircraft

 

Originally the J200 (first with wing tanks) had a twin valve tap where the single tap is now, one for each side, they used gascolators and a central vent above cockpit (sharks fin) After a number of venting and fuel management problems they came up with the setup they have now. Earlier conversions see the header tank under PAX seat.

 

With a low level light fitted it should be the best fuel supply setup. In almost ANY fuel starvation situation you should get ~ 10 minutes warning. Even Piper etc dont give that and your relying on a 30 year old guage.

 

I believe the J230 was never tested in one empty tank one full tank during spin testing so these taps are supposed to be deleted on models with longer wing.

 

 

[dazza 38]

I agree Jetjr, the piper fuel swith position, being on the fueselage side wall near the left knee is a silly position plus the other problems you have mentioned.Trouble is, with aviation.(as you know). For Piper to move the fuel selector would probably cost them a hundred thousand or more in a redesign. Who owns Piper these days lol? They change ownership every couple of years.

 

 

[Modest Pilot]

Couple of points about 4 way valves. First the both on position is usually 180 deg from the off position. A number of Cessna's have tried a takeoff in the off position, the engine often cuts at around 50 feet. The Andair fuel valves have a pull up pin before you can go to off, not perfect but maybe a help. On low wing aircraft with no header tank, with low fuel and the selector in the both position un-porting can occur, air can enter the system and cause at airlock. Vans aircraft kits no longer have fuel valves with a both position after a company employee had an engine stop on final and right off his brand new pride and joy. Apart from the draining on the ground problem on Jabs in the air unless you keep the aircraft perfectly trimmed for yaw (no rudder trim on Jabs) fuel will always drain from one tank first and you will fight a wing heavy situation which is a pain on long flights.

 

 

[kaz3g]

Interesting The C172 fuel system.In the latest Crash comick , there is a story of where the handle was thought to be on the both setting, but was actually in the off setting.EFATO happened.

Yes, Dazza....it is a trap for young and old players that one!

 

Also the fact that many of them only hold 140 litres and not 160 like their PA28 stablemate.

 

Kaz