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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-555777@logan.com>
Subject: Re: [FlyRotary] power sag
Date: Sat, 4 Dec 2004 15:12:02 -0500
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Steve, I can tell you that if you get the old spark plug "SAG", it will
happen at the moment mostly likely to require a new seat cushion.  It
generally happens to me during full power (or nearly so) engine conditions.
Rpm will drop 200-300 rpm (depending if SAG on both or one rotor).  Don't
know if you situation was due to SAG, but a new set of plugs clears it up
immediately.  Sometimes, change the mixture control seems to help -
sometimes not.  Most of the time it clears up after getting your heat
beating a bit faster.

Ed Anderson


----- Original Message -----
From: "Steve Brooks" <prvt_pilot@yahoo.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, December 04, 2004 9:23 AM
Subject: [FlyRotary] power sag


> I went to South Carolina Thursday to replace the fuel regulator, and do
some
> flying.  I replaced the regulator, and ran the engine some on Thursday,
but
> no flying because it was getting dark.
>
> On Saturday, I went to fly, and had some trouble getting it to stay
running
> due to the cold temperatures.  I probably didn't keep it rich enough, long
> enough.  I taxied out to the far end of the runway (5000'), and took the
> runway for take off.
>
> As I accelerated to about 90 kts, I was just rotating when to power
dropped
> substantially.  I cut the throttle, and aborted the takeoff.
>
> I don't know exactly what caused the sag.  I pulled the throttle all the
way
> back during the aborted takeoff, and the engine died.  I have my idle stop
> set a little low (400 RPM's), and usually don't pull it all the way off,
but
> even when I do, it has never died.
>
> I restarted it, and ran the power up to about 4000, and it seemed OK.
>
> Another issue with my right main wheel bearing prevented me from making
any
> more high speed runs.  The right wheel has been making noise, and I was
> trying to resolve it with the mfg, but during the aborted take off, it
> really made allot of noise, and also vibrated pretty good at one speed, so
I
> decided that I better get that fixed before doing any more flying.
>
> I changed the fuel regulator, so I guess that it could have been some air
> still in the fuel line, but the engine had probably run for at least 10
> minutes prior to the take off roll.  It also could have been some water,
> though I've never found any to date during preflight.  The engine was
> running at 5 lbs of boost and about 5000 RPM's.  It was about 45 degrees,
> and the plane was accelerating very strong prior to the power loss.  I
don't
> know if it would have picked back up, but I was glad that it didn't happen
5
> seconds later.
>
> Steve Brooks
>
>
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