opinion sought

[storchy neil]

how hard is it to follow an installation manual

 

rotax installation manual for 912 aircraft engine states that return line to tank is required page 14 -3 date mod 1998 09 01

 

does your plane have this

 

if you don't is your plane legal

 

weight and balance you have your aircraft repaired or a new gadget put in do you have to do a new weight and balance

 

storch s manual maintenance page 17 30 10 07 every variation needs a new weight and balance

 

as a pilot can you do a weight and balance on a 24 reg aircraft neil

 

 

[rgmwa]

The only experience I have is with an RV-12. It has a return line. I don't know who can do a W&B on a 24 reg aircraft.

 

rgmwa

 

 

[nong]

how hard is it to follow an installation manualrotax installation manual for 912 aircraft engine states that return line to tank is required page 14 -3 date mod 1998 09 01

does your plane have this

 

if you don't is your plane legal

 

weight and balance you have your aircraft repaired or a new gadget put in do you have to do a new weight and balance

 

storch s manual maintenance page 17 30 10 07 every variation needs a new weight and balance

 

as a pilot can you do a weight and balance on a 24 reg aircraft neil

If you have an RAAus plastic card that is current...why not look at it and see if you have 1, 2, 3 or 4 Maintainer level. If so, why not read your RAAus Tech Manual to see what your Maintainer level allows you to do?

 

 

[Dafydd Llewellyn]

how hard is it to follow an installation manualrotax installation manual for 912 aircraft engine states that return line to tank is required page 14 -3 date mod 1998 09 01

does your plane have this

 

if you don't is your plane legal

 

weight and balance you have your aircraft repaired or a new gadget put in do you have to do a new weight and balance

 

storch s manual maintenance page 17 30 10 07 every variation needs a new weight and balance

 

as a pilot can you do a weight and balance on a 24 reg aircraft neil

I suggest you check this; aircraft weight & Balance is controlled by CAO 100.7, which is enabled by CAR 235 - and as far as I am aware, RAA does NOT have an exemption to that regulation. There is normally a page close to the front of the aircraft log book for the purpose of recording changes to the aircraft empty weight and CG. See below for a typical sample

 

Log book W&B page pro-forma.doc

 

Log book W&B page pro-forma.doc

 

Log book W&B page pro-forma.doc

[cscotthendry]

WRT weight and balance. I also believe that there are clauses that state that weight changes that are less that a specified portion of the aircraft's weight are not considered "significant" and don't require a new weight and balance. An example that I can think of might be something like adding a new placard in the cockpit. The clauses I read (can't remember the reference now) were a bit more generous than just allowing things like placards.

 

Also, the return line to the tank is from the vapour bypass valve which is reccommended to prevent vapour locking in the fuel lines. If your engine doesn't have this bypass valve and its attendant return to the tank, there is a possibility in your system of having engine troubles from vapour locking. Regardless of whether it's legal or not, if you don't have this valve, you could have an engine stoppage.

 

I had a trike that didn't have one of these valves and the manufacturer ran the unshielded fuel line UNDER the intake manifold. On warm days my trike would vapour lock if I did some circuits, then shutdown the engine for a few minutes and then restart and do a takeoff.

 

 

[Dafydd Llewellyn]

WRT weight and balance. I also believe that there are clauses that state that weight changes that are less that a specified portion of the aircraft's weight are not considered "significant" and don't require a new weight and balance. An example that I can think of might be something like adding a new placard in the cockpit. The clauses I read (can't remember the reference now) were a bit more generous than just allowing things like placards.Also, the return line to the tank is from the vapour bypass valve which is reccommended to prevent vapour locking in the fuel lines. If your engine doesn't have this bypass valve and its attendant return to the tank, there is a possibility in your system of having engine troubles from vapour locking. Regardless of whether it's legal or not, if you don't have this valve, you could have an engine stoppage.

 

I had a trike that didn't have one of these valves and the manufacturer ran the unshielded fuel line UNDER the intake manifold. On warm days my trike would vapour lock if I did some circuits, then shutdown the engine for a few minutes and then restart and do a takeoff.

CAO 100.7 para 6 covers this:

 

6 Record of weight alterations

 

6.1 A complete, current and continuous record of changes in empty weight and empty

 

weight centre of gravity position and, where appropriate, operating weight and

 

operating weight centre of gravity position, shall be maintained for each aeroplane and

 

rotorcraft and this record shall contain details of all alterations affecting the weight

 

and balance of the aircraft.

 

6.1A If changes to an aircraft’s empty weight or operating weight occur due to changes in

 

the aircraft’s equipment, the aircraft’s equipment list must be amended in accordance

 

with the equipment changes.

 

6.2 A new record of weight alterations shall be raised after each weighing.

 

6.3 Unless otherwise agreed to by CASA, the load data sheet for an aeroplane or

 

rotorcraft shall be renewed before further flight whenever, as the result of a

 

modification or as otherwise shown in the record of weight alterations, changes

 

exceeding the following have occurred:

 

(a) for aeroplanes:

 

(i) the empty weight has changed by more than 0.5% of the max. T.O.W. or

 

10 kg, whichever is the greater; or

 

(ii) the empty weight centre of gravity position has changed by more than 2% of

 

the maximum permissible centre of gravity range or 5 mm, whichever is the

 

greater;

 

So whilst ALL changes must be recorded, the Load data Sheet does not have to be renewed unless the changes exceed those limits.

 

 

[storchy neil]

for aeroplanes from maintenance manual for storch s every variation due to installation of new components or repairs and painting implicate a new calculation of the empty weight and relative positioning of the centre of gravity page 18 30 10 07

 

so I through out the maintenance manual there for I am not complying to the manufactures directions

 

return line to tank it has been stated to me that this line only takes vapour back to tank by a l2

 

on several occasion my fuel pressure gauge has been on 7 bars and has had 2 new needle and seats installed by lame l2 l4 in under 150 hrs

 

when in the hell is the training of a l2 going to be more through neil

 

 

[thommo]

The fuel return can be pumbed back into the fuel gascolator on the top if it's fitted with one.

 

 

[crashley]

doesn't the return line have to return to the tank if it goes to the gasculator which is after the fuel pump it wont allow excess fuel to flow back to the tank as it will be under the same pressure as the fuel supply

 

 

[storchy neil]

sorry thommo as I see this you would be against installation manual directions so once again through out rotax manual:im stupid: neil

 

 

[thommo]

Well have a look at a few installations that are around. You will find a few done this way. Problem that was happening if you had full tanks fly on the left tank with the return into the right tank that tank would over flow out the vent. That's what I was told.

 

 

[storchy neil]

thommo storch flight manual page 28 20 12 o6

 

before starting engine fuel faucets lh open rh closed

 

this is so what you have said does not happen

 

after 20 minutes of flight turn on right hand tank

 

i stand to be corrected tecnam sports star Texan and a couple of others state this in flight manual neil

 

 

[metalman]

I've run the return line back to the collector tank in my aircraft, so far works okay , I do know a lot of older installations don't have a return line. The early Skyfox didn't have them , not sure about the gazelles.

 

Matty

 

 

[Dafydd Llewellyn]

I've run the return line back to the collector tank in my aircraft, so far works okay , I do know a lot of older installations don't have a return line. The early Skyfox didn't have them , not sure about the gazelles.Matty

Please pardon my curiosity; you seem to be talking about something I'm quite unfamiliar with. Precisely where on the engine does the return line start? What is it returning fuel from?

 

 

[metalman]

there's a distribution block between the carbs that also has a restricted outlet for a fuel return to the tanks, it seems to be a later 912 thing as I don't think the early installs had it

 

Matty

 

 

[cscotthendry]

The proper Rotax item is a 4 way block with one input and three outputs. Two of the outputs go to the carbs and the third output has a restricter nozzle in it and it is plumbed back to the fuel tank. On my airplane, I did this by having two T units. The first T has the restricter (a carby jet) threaded into the base leg and the fuel from the pump goes into one side of the top of the T. The other side of the top of the T is the outlet to the next T that splits the fuel flow to the carbys.

 

The restricter outlet should be at or as near as possible to the highest point in the fuel delivery lines so that any bubbles will rise to that point and be routed back to the fuel tank. In my system, I didn't bother firesleeving the return line. I also put standoffs between the lines that go to the carbys and the intake manifolds. When the engine is shut down after a run, the manifolds get hot enough to burn your hand on and easily hot enough to vapourise petrol.

 

 

[Dafydd Llewellyn]

there's a distribution block between the carbs that also has a restricted outlet for a fuel return to the tanks, it seems to be a later 912 thing as I don't think the early installs had itMatty

The proper Rotax item is a 4 way block with one input and three outputs. Two of the outputs go to the carbs and the third output has a restricter nozzle in it and it is plumbed back to the fuel tank. On my airplane, I did this by having two T units. The first T has the restricter (a carby jet) threaded into the base leg and the fuel from the pump goes into one side of the top of the T. The other side of the top of the T is the outlet to the next T that splits the fuel flow to the carbys.The restricter outlet should be at or as near as possible to the highest point in the fuel delivery lines so that any bubbles will rise to that point and be routed back to the fuel tank. In my system, I didn't bother firesleeving the return line. I also put standoffs between the lines that go to the carbys and the intake manifolds. When the engine is shut down after a run, the manifolds get hot enough to burn your hand on and easily hot enough to vapourise petrol.

OK, I deduce from that that the fuel supply from the tank passes via the electric pump and the gascolator, to the engine-driven pump, and thence to the distributor block, from whence a supply line goes to each carburettor plus a restricted outlet for the return line? If that's the case, it is a form of vapour-purge system to prevent vapour-lock - and I would think that it should return to the fuel tank. GA aircraft using injected Continental engines have a similar system; on things like Beech 23s, it goes to one main tank, so you must remember to use that tank first, or fuel will be pumped overboard. On more expensive aircraft, there is a second stage in the main fuel tank selector that routes the return fuel to whichever tank is in use. If you return it to the gascolator, you risk total vapour lock.

 

 

[facthunter]

Whether it is vapour purge or just a "higher flow and keep it cooler" system may be debated. A problem with assymetric fuel load is a possibility.( It's not critical just something to be aware of). If both tanks are common, flying in balance should cover it. I personally like the opportunity to select individual or BOTH as an option. With that situation you could overflow return fuel if it went to a full tank with a primitive vent system, or get out of balance with individual tank selection. Both situations are not excessively difficult fuel management situations. The pilot should have control of where the fuel is coming from. Nev

 

 

[Dafydd Llewellyn]

Whether it is vapour purge or just a "higher flow and keep it cooler" system may be debated. A problem with assymetric fuel load is a possibility.( It's not critical just something to be aware of). If both tanks are common, flying in balance should cover it. I personally like the opportunity to select individual or BOTH as an option. With that situation you could overflow return fuel if it went to a full tank with a primitive vent system, or get out of balance with individual tank selection. Both situations are not excessively difficult fuel management situations. The pilot should have control of where the fuel is coming from. Nev

Well, either way it's a vapour-lock precaution; whether it was necessary for compliance one cannot know, so one must assume the worst scenario. I agree re the fuel system operation points; a fuel system should look after those details itself, tho I've yet to see one that stays in balance on "both".

 

 

[facthunter]

The Rotax has a very low fuel pressure specified so keeping the fuel cool is more important than where higher pressures are used. Cowl temperatures are high enough in some installations as to not require carb heat to be installed. You can't have it that way and not lose power, to some extent. Lagging/shrouding the fuel lines should be done thoroughly. Nev