Artouste II C-6 starting problem

[Rotorgoat8]

My Alouette II had been sitting awhile whilst being painted and now doesn't want to complete the start cycle. Starter turns, green light, yellow light, T-4 rise about to 100*, RPM 7000 but doesn't reach self sustaining speed prior to about 15 seconds then I go to "Off". The fuel cock cycles correctly and both spark and atomization of the ignitors are good. the book says check the idle fuel valve on the fuel pump. Wondering if there are any other tricks I should try prior to pulling the pump.

[sycamore]

Battery a bit low,or maybe air in the system ?

[hihover]

Can you hear the boost pump running prior to engine start? Sounds like air in the pipes to me. Perhaps external power (lots of it) and a couple of attempts might be the way to go, however, I expect you may already have done that by now.

Tam

[helichoppers]

We had a simular problem, it was the P2 air pressure sensor on the top of the engine. Where it had sat for a while a small amount of corrosion built up therefore not allowing the sensor to work. Get someone to remove the valve clean it out, lube it and operate it a few times before re-installing.

Our one went through the start cycle then after about 30 seconds cut out, in the flight manual the is a section that gives the the start light sequence to help you diagnose.

Hope this helps:)

[Rotorgoat8]

Thanks for the input. The battery is in excellent shape. The boost pump is running (I've been giving it at least 30 to 60 seconds prior to start). My P-2 switch has the mod that operates it via fuel pressure as opposed to air pressure (if I understand it's function - it would not allow the start to begin or would cut out the starter prematurely if it malfunctioned). I've done about 10 attempts over the past 4 or 5 days (no more than 3 without a full recharge of the battery) and I would think that would have purged any air out of the system-but possibly not. After each start attempt I get about 2 or 3 tablespoons of fuel from the can drains so it must be getting some fuel from the idle mixture jet (I think the micropump ceases almost instantly when the Start switch is set to OFF and the fuel cock closes).

[mtoroshanga]

Have you checked that the ball in the 4-way valve supplying the torch igniters is free.Some engines have an access boss on top of the valve so that you can lift the ball out witth a magnet and clean it.Take out a torch igniter and blow through it,they can block as well and need workshop servicing if they do.

[cpt]

If I remember well, the 4 ways valve selector is here to select fuel or P2 air to igniters during and after the start-up sequence. Apparently, in this present situation, the start-up sequence is correct, but for some reason, fuel is not allowed to injection wheel. Strange, as long as the fuel cock cycles correctly...did you check the timing of the sequence? maybe the cock closes too early if it "believes" the starting sequence is too long,(electromecanical thermal contactors..."T5R ?")
Did you try to pull the starter cb just after the micropump light goes off, this should prevent it to close prematurely (sorry for not beeing more accurate but it makes a long time and no documentation immediatly available)

[Rotorgoat8]

Thanks for the continued input, every little bit helps. We checked out the ignitors and have good spray pattern and spark. We can visually see the indicator on the fuel cock opens and stays open during the start. I also get a small T-4 rise to about 100*C which, I think, tells me the ignitors are lighting up. I haven't been leaving the starter engaged long enough to activate the T-5 relay (~50 Seconds) and it continues to motor (Green light) until I go manually to OFF after approx 15-20 seconds. Normal light off should occur at about 3 to 4 seconds into the start sequence.
The book says to look at the idle jet valve in the fuel pump and after further study I see that the idle flow goes through the Governor to the slinger wheel. I guess that adds another possibility to the list.
I'll investigate the 4 way valve. Thanks again to all.

[Ricktye]

And the Micro Pump is actually providing enough pressure?

R...

[Rotorgoat8]

Yea, we did a atomization test per the manual and got the nice 30 degree spray pattern and separately sparks during the ignition test. I think that is what is giving the T-4 rise to about 100*C.

[AvioCopter]

It seems to me that fuel cock is not really opened
in spite of visual indicator. Did you remove it and
clean it and check operation separately?

[enstrompilot]

hi

have you tried disconnecting the high current power lead to the start box (big plug one heavy wire, one Pin) and doing several start/stop cycles, this has the effect of cycling the auto start sequence (without wasting battery energy). You should see some burn gases from the injector/sparks, on shut down the 'blocked' light should come on for 10-20 secs and the start sequence card should reset.

Do you have access to the start card, robinet, cracker test box and/or a replacement start card.

I can lend either if that is of any help

the P2 sensor is a pressure sensor with change over switch contacts. Its roll is:-

1, in order to initiate start the p2 pressure switch must be relaxed (pins 1 & 2 closed) this allows current (via other conditions) to the starter contactor

2, later in the start sequance, when the pressure is sufficient the switch changes state (1&2 open 1 & 3 closed) which removed current from the starter contactor (thus turning off the starter) this can also happen if the t30 timer is exceeded.

P2 is an air pressure switch prior to MOD nn(?) and after MODnn (which all C6's should have had) is a Fuel pressure switch set such that the fuel tank boost pump will not trigger it, only the engine driven pump at more that 16,000 rpm can provide sufficient pressure.

the conditions exhibited on failure are:-

1, if not closed prior to start attempt, the starter contactor will not allow the started to spin the engine, but most of the rest of the starter sequencing will work.

2, if not sufficient pressure or switch faulty the starter contactor continues to drive even when the engine achieves self sustaining speed (this can be solved by pulling and then reseting the starter circuit breaker)

1 can be proven by unpluging the plug at P2 then try a start - no engine rotation but start sequence will seem normal


from conditions described I don't think P2 has any part to play, but if you need to borrow a spare to prove the point I can lend you a new unit.

my guess is, I think you have insufficient fuel/fuel pressure, or the main fuel value is failing to open.

The electric fuel valves (robinet) are sensitive to low voltage and they get 'sticky', they are supposed to operate with battery voltage as low as 11v but when not used for a while tend to need more volts just when, because of high current draw, the voltage can be v low. The test box allows for the cock to be 'exercised' and allows for application of low volts to ensure the cock works at less than 28v.

What voltage do you get as the engine RPM rises through, say 8,000 rpm ?. It can be low but should be above 15-16v, even then a 'sticky' electric cock (painful) would cause the problems you discribe (if battery volt is a low as 10-12 your battery may have one or more 'poor' cells - have you and external start source ? (and cables ?)

The fuel system draws fuel via the fuel tank lift pump, filter, bypass valve, manual cock then to the engine driven fuel pump, etc. There is a return to the tank via a restricted valve (located low on the p1 diagonal tube to the rear od the fuel tank), may be worth checking as no restriction will cause low pressure from the boost pump

maybe air in the system, you could crack a joint near the micropump to blead air out ?

is the micropump good? - sounds like it as engine RPM is rising but acceleration is not sufficient (which points to main fuel and the prime suspect the robinet)

are both crakers sparting, often the craker box fails on one half and for a while the engine starts OK but the non sparting igniter can then soot up

is the fuel filter v clean ?

There is a small strainer/filter in the governor which may be blocked (in the body of the governor at the inlet pipe from the engine fuel pump) (a long shot)

do double check that the manual fuel flow lever is allowing the manual 'emergency' fuel shut off value to FULLY open ( a long shot)

I still suspect the electric fuel valve, I have spares if you need one to disprove the point.

let me know if I can help or if you need to borrow any parts/testers to help with diagnostic (where are you based ?)


Ian

[Bushrat]

as said earlier four way valve...

[Rotorgoat8]

I'm away on business until later this month so won't be able to continue the trouble shooting until then. However I was thinking that the possiblilty of the fuel cock indicator being misleading should be checked.

Anyone wishing to see a couple of starts that were done prior to this problem arising can go to YouTube and search Alouette 2 001. Sorry, I don't have the smarts to put the link here. On the start with no light off you can see the amount of fuel fogging and I'm not getting any of that now.

6Uc_RQXMs_g

Again, thanks to all. You've given me plenty to work on.

[Rotorgoat8]

Just got back at it today and decided to try the easiest tests first. We removed the electric fuel cock and reconnected it to the electrical connector. Then initiated the start with my assistant at the fuel valve with a pair of duckbill pliers ready to rotate it 90* at approx 4 sec into the sequence. We got a normal start with about 275* T-4. and all parameters normal.

The head scratcher here is that with the electric fuel cock connected to the electrical connector-- it rotated 90* as it should and also rotated back 90* at shutdown (I shut it down by turning the Start switch to OFF and using the Fuel Cut-Off lever). The fuel valve is not stiff and is easily turned with the pliers. Is this a characteristic of a "weak" electric fuel cock? It appears that the electric fuel cock is the problem unless I'm missing something else.

[Rotorgoat8]

Once again I'd like to thank all those who offered help. A couple of notes to add: The 4-way valve (I had to dig for this one) is on the Astazou II engine only and the electric fuel cock (and fuel valve) is of a different type also, although it functions with the same circuit inputs. I should have remembered this as I was a tech on the 318C but that was over 40 years ago and the hard drive is old and corrupted these days.

[Ricktye]

Glad you finally got it figured out. Like you, most of my time was on the 318C with the Astzou engine. Great old aircraft and as we all know one of the most reliable built, but they did/do have their quirks!

R...

[jay_jay]

Hello I need an advice regarding the starting of this engine .
Since I change the Fuel cock our starting is not as good before.
When I switch to run the T4 and Eng. RPM rises but in a few sec. the T4 and ENG. RPM has an erratic reading..after I switch to OFF.
What does it mean? I do change the fuel cock bcoz its broke..
Most of the time we start the engine by doing reset the T5 timer..It takes two attempts to be succesfull.
Thinking that the timer doesn't work properly?
What is the cause of this problem although Ive change the starting block and fuel cock with a good one.

[Rotorgoat8]

Not sure what you meant by starting block that you changed but in the Automatic Control Box the T5 timer has both a resistor and a diode that could be acting intermittently causing the bimetallic strip to move to quickly or slowly depending on the circumstance. What engine do you have? As the Artouste and Astazou have some different inputs to the ACB during the start sequence. If the contacts on the T5 are sticking and won't reset, you can clean them up with a fine contact file. Try changing the card in the ACB if you have a servicable spare. Good Luck!

[jay_jay]

Thanks!! We have the Artouste II C-6 engine
Ive try to run with this control Unit on our other alouette but it works.It means the control unit is good. As of now my suspect is the wiring.. any more suggestion regarding this may help. Thank you sir

[Rotorgoat8]

I had a similar problem with a fuel cock. It indicated that it was opening (visual indicator) during the start sequence but the engine would not light off properly (just a slight rise in T-4 which indicated that the micropump and ignitors were working). Just to check it I removed the fuel cock and manually turned the fuel valve to open and the engine lit off OK. I had to put in another fuel cock and it works fine now.

[jay_jay]

thank you sir for the responce..
I will try to remove the fuel cock and open up only the valve.
And try another attempt.. good day!!