Message-ID: <000d01c3d388$03c8a540$1702a8c0@WorkGroup>
From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2917087@logan.com>
Subject: Re: [FlyRotary] Re: alcohol in mogas...test and avail
Date: Mon, 5 Jan 2004 07:32:41 -0500
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Subject: [FlyRotary] Re: alcohol in mogas...test and avail


> Marc and all, Happy New Year!
>
> This idea of water, alcohol and mogas is really interesting to me right
now!
> This past week, I tried to get my plane moved from Pensacola to
Statesville,
> NC, and spent a few days fixing a fuel leak, exchanging fuel several
times,
> and flying the bird to make sure it, and I, were ready for the 500nm
flight.
> Here's the blow by blow:
> 1. In test flights the engine ran great with temps and pressures in the
> green.  Occasionally there was a little vibration and/or burp, and with
> power reduced for decent, a miss.  Once on the ground, the engine ran
rough
> once for a second or two, then smoothed out again.
> 2. Yesterday, I took off for the  trip home after a very damp, foggy two
> days.  Climbing through 2500 feet, the engine coughed and quit, coughed
and
> quit, and then restarted with no other problem, but it seemed a little
> rough.  The whole thing lasted, maybe two seconds which seemed like two
> years. (Ed, I'm beginning to understand how you have felt.)
> 3. Safely returning to the airport, the engine ran rough for another two
> seconds on the taxi in, and again before I shut it down.
> 4. In trying to figure this out, the first thought I had was contaminated
> fuel, although pre-flight sump drains showed no visible water.
> 5. Marc's offering on water and alcohol seems very timely, even though it
> may not be the cause of my problem.
> 6. My plan, so far, is to drain and refill the fuel tanks, then do a
> thorough assessment of the computer set up.
> 7. I hope all you guys can help me figure out this problem.
> Regards,
> Tommy James<><
>
>
 Hi Tommy,

    Glad to hear the engine didn't stay stopped - raises the adrenaline
levels even when it misses, and the flow of time is definitely altered {:>).

    I suspect you are correct that it is fuel system related.  If it were
ignition, the odds are it would quit completely rather than just run rough.
Did you by any chance notice your  RPM,  EGT, fuel pressure or air/fuel
mixture LEDS when this was happening.  I know - tough to divert you
attention to details when this happens in the air, but you might pay some
attention to what those   instruments are telling you when if happens on the
ground.  Also, did you ever have any luck with the simple fuel flow meter?

I would suspect that perhaps too little fuel might be the cause,  my
experience has been that once the engine is running above 4000 rpm, you can
pump almost any amount of fuel into them and they will continue to run
(almost impossible to flood to the point of quitting once at those rpms) as
any unburned fuel is apparently blown out into the exhaust headers.  I have
notice no missing or quitting under too much fuel although my EGT will drop
several hundred degrees when too much fuel is flowing.

However, too little fuel and the engine will start to run rough at some
point and may quit.  Just a thought.  Too little fuel could be due to water
contamination, restricted fuel filter, low fuel pressure, malfunctioning
injector, fuel MAP not set appropriately, etc.

The only thing I can think of that would result in too much fuel would be:
Fuel MAP not set appropriately and/or malfunctioning injector.  I had one
injector that would periodically stick open pumping fuel into the engine -
but while the EGT for the affected rotor would drop approx 300F, the engine
did not miss or quit - it did, however, develop a different "tone" to the
engine sound.

It does not sound like the spark plug SAG, however, depending on how many
hours your have on your plugs, you might try a new set of plugs  just to see
if they made any difference.

    If no water is visible then here is another suggestion - check any fuel
filters.  I am unfamiliar with what your fuel tanks are make of or if you
seal them with anything.  I recall a few years back there was some
consternation that the fuel tank sealer used on the RV's metal fuel tanks
were adversely affected by auto gas and would start to peel off and plug
fuel filters.  Fiberglass tanks have been know to shed fibers that
eventually plug up the filters.

Hope you get it fixed quickly.  I just hate intermittent problems - well,
intermittently quitting engines while in the air are better than one that
stays stopped {:>)

Good Luck and be careful

Ed Anderson