David:

Similar problem on my IV-P recently.  Turned out the M.P. transducer
was faulty.  The plane was down
for a couple of years changing out a cracked windshield.  Evidently,
the transducer got contaminated from solvent or epoxy. or whatever.

Good luck with the trouble shooting,

Bill H.


On Wed, May 23, 2012 at 5:17 AM, David M. Powell CRFA
<superdmp@sonic.net> wrote:
> Hi all,
>
> I've got a strange problem that I'm hoping someone has seen before.  My
> mechanic normally works on certified aircraft, so he's contacted Lancair;
> but I think the answer lies here with the real experts.
>
> On a return from a cross country, I wasn't able to get my RPM and manifold
> pressure to 'square up' the way I wanted; but the trip did end without any
> major incidents(a little backfiring from the rookie pilot not slowing early
> enough) and I landed home safe.  I asked the mechanic to check out the
> airplane.  The mechanic noted that after starting the engine, the manifold
> pressure(vacuum) indicated down in the mid teens and stayed there.  He
> wasn't able to increase it either by increasing RPM or by adjusting the prop
> governor (blue knob).  We were able to cycle the prop and note a decrease in
> RPM, but the manifold pressure never came up (while the engine was
> running).  The pressure read normal altimeter setting with the engine off.
> We had planned on a flight to see if the indications were different in the
> air, and figured it was just a read-out problem and not an airworthiness
> issue.  On the takeoff roll, I noted that the RPM's exceeded red-line on my
> gauges; with less than full power (I roll in power gently).  I aborted the
> take-off roll as it was apparent I had a runaway prop.
>
> To make this all a bit more interesting, I purchased this airplane and flew
> 5 hours cross country back home, did an additional 15 hours of flight
> training, and never once added a drop of oil.  It has always been at exactly
> 7 qts.  I noticed I'm now at 6 qts, and on pre-flight prior to my trip home
> from my cross-country, I noted 6.25 qts of oil.  Oil pressure and
> temperature all were normal throughout.
>
> Any thoughts?  I'm thinking the prop governor needs to be replaced.
>
>
> Thanx for all the great help,
> Dave
>
> P.S.
>    Looking forward to meeting some of you in Arizona in September.
>
> David Powell CRFA
> superdmp@sonic.net
> (386) 868-5858
>
>
>
>