Thanks Cuzzy Bro appreciated ;)

WLM,

Sounds expensive!

Where was the noise from? The engine or the EMB? T model or P model?

Sounds like your starter contact. Fuel from aborted/failed start?

Loose connector not allowing enough current - contactor bouncing in and out?

Where? ECD is the holy grail.

The 135 can be a little tricky to the uninitiated!

Igniters typically don't go "bang".

Please let us know what the issue is once you find out.

Sounds like there may have been residual fuel in the chamber on start up. The question would be, why?

Pedal Forces
 

Anybody know by how much (in Newtons?) the pedal forces increase following a number 2 hydraulic failure? Nothing in the RFM - it just says "significantly". CAA medical department issue following knee surgery.

About the same as an EC130? No servo, same fenestron mirror image.

HYD System on the tail is only there for SAS/AP control.

Ask ECD?

Do NOT try to find out by turning "hydraulics off" in flight. :=

Thanks rvdt. Anybody got a sensible answer?

Hi Guys

Well when the EC engineers arrived, sure enough the problem would not repeat itself :confused:

Did every checks possible under the sun and still nothing.. so went for a short flight test and still nothing upon returning..

THEN it happened during the next start... the culprit was my external home made EPS using 2 x 12V + 1 6V batteries (30V) . We made that unit 2 years ago when we could not get a 28.5V StartPac locally. It always worked up to now, mainly running Avionics during ground tests

If using the aircraft battery or the 28,5V StartPac, no issue; but when using the home made cart, the bang bang started and a very slow starter spooling up

So that's what the engineers ascertained the problem to be:O

Recently I did the mandatory fuel system check and started the groundrun with about 180kg in the main tank. The transferpumps were switched off and the fuel level in the main tank was still reducing until reaching about 160kg and thereafter the fuel level in the supplytanks was getting lower. In the ASB EC is mentioning this fact to be normal. I do not understand, why the main fuel is reducing without the transferpumps?


skadi

The transfer pumps supply fuel to the supply tanks via pipes, at a rate that is higher than the engines can suck it up, the excess fuel pores back into the main tank via 'holes' through which the transfer pipes run, above 160kg this means all tanks are essentially connected. Hence the fuel runs through the holes to the supply tank until this point.

At a certain flight attitude you can reduce the main tank further without transfer pumps.

Hard to explain without a diagram.

http://img30.imageshack.us/img30/3640/135tank02.jpg

We had exactly the same; 159 till 139 after XFER pumps OFF, sucking at it for almost 15' before supply tank indication dropped.

I'm thinking the fuel flow of each pump being more than 12L per minute has some inertia to it before it stops flowing back from supply to main tank through overflow.

I did two runs yesterday on one we started with 100KG in the main and this burned off with the xfer pumps de-selected until 52kg only then the supply tanks started to show a reduction. We then did the second aircraft where we drained the main tank to 60kg before we started the test thinking it will take 10kg before we start to see the supply tanks dropping except we didn't. We had 12kg left in the main before the supply showed any signs of dropping.

The third aircraft the day before though started at 57kg.

I am still waiting for an technical explanation for this "phenomenon", the overflow channels are way above these levels, so the answer from RWB2 doesnt satisfy me.


HAPPY NEW YEAR

skadi

Skadi,

The transfer pipes run down to the bottom of the supply tanks, so you get a siphoning effect. Problem is a faulty NRV could in theory, let fuel flow the other way!!

So in every 135 the NRV is faulty? That makes no sense to me.


skadi

Skadi,
Either I have misunderstood your question, or you have misunderstood my answer.
The transfer pipes run to the bottom of the supply tanks, this will cause a siphoning effect so fuel will continue to flow when txfr pumps are off which would account for your fuel anomalies. This is not a fault.
My comment about the NRV is an observation of what might happen if one were to fail.

Bollix.

Does the "phenomena" spoken of coincide with ~ 3 minutes.

If so you will have to dig pretty deep for an answer.

Skadi, post #947

If the main tank was indicating only 12 kg before the indicated levels of the supply tanks began to drop...the aircraft has at least one faulty level-detecting probe in its fuel system....that's no phenomenon, it's a fault.

Were the transfer pump FWD and AFT illuminated when you started the check ?

EPAC please explain your thinking.

Why would there be a faulty probe? All that's happening is the main tank emptying itself due to the syphon effect with the xfer pumps switched off as per AD.

But I might be missing something...

Would that be the well known 'uphill syphon effect'?

TeeS