"Conventional wisdom" is - every engine should have a filter to keep sand
(and other hard parts) out of engine.
    -  This comes up occasionally on the RV-list.
    -  I believe Mooney has a "bypass-the-filter" for use when airborne to
eliminate the slight drop in manifold pressure caused by the filter's
restriction to airflow.  To me, that is the ideal system - have to have a
filter on the ground; don't need it when airborne if you want to race or go
high and/or fast.  Dry paper filters drop 1 inch Hg, oiled foam filers drop
at least 2 inches - dry is better, therefore.

Back in 1964 an Explorer Scout post I was assisting with at George AFB, CA,
bought an old truck with dump bed - had a 6 cylinder flat head engine.
After overhauling it, we used it to go out to Cuddyback Range (when closed!)
and picked up "darts" (the air-to-air gunnery targets towed behind a fighter
for other fighters to shoot at).  We'd use an axe to cut off the honeycomb
wings and salvage the aluminum "backbone" and other metal parts, then sell
for scrap as a fund raiser.
    -  Well, we overhauled the engine as soon as we bought the truck, then
went to the desert range a few times.  Wasn't long before the engine wasn't
running so well - pulled the head and found lots of sand grains smashed into
the valve seats and on the mating valve faces - we'd run the truck in the
desert without a filter!

OK, so we don't have valves in a rotary, but we have "apex seals" that hate
foreign matter interference . . . . . This is similar to people who fly
carbureted engines with no "carb heat" system installed - just waiting for
the "right circumstances". . . . .

Ed, I recently had a valve seat disintegrate in one of my Ford Escorts -
blew hard chunks out both the intake and exhaust - shook out parts from the
catalytic converter, then, after reassebling the engine and cranking, got
the "loud tapping noises" again (more hard parts on top of piston) and found
LOTS of stuff kicked back into the INTAKE manifold, mostly up in the TOP LOG
from which the 4 runners came down to the intake port flanges.  When I first
reassembled the engine, I only checked the lower part of the manifold, the
holes that mate up to the head - there was a bit of stuff there but I never
suspected it would blow up thru the runners into the top log.
    -  Therefore, suggest you remove your intake system and examine for
trash.  I had to take my manifold to the local car wash and use hi pressure
to blow it clean.

David Carter

----- Original Message -----
From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, April 12, 2005 6:22 AM
Subject: [FlyRotary] Re: Latest on the Motor Trouble


Thanks, Paul

I do not have an air cleaner nor screen on this intake - had a screen on my
previous intake.  I guess its always possible for a prop to blow FOD into my
oil cooler inlet (right up under the spinner) - but unlikely.  But, clearly
something took out the apex seals on #1, no question about that when one of
them is in three pieces.  Its beginning to look less likely that the spark
plugs were responsible - just a coincident on the timing.  Hopefully I'll
find out this morning.  I had though that perhaps pieces of the plastic
plenum might have done the job - but all pieces accounted for.

I need to examine my intake manifold just to see whether any incriminating
evidence might be laying in it.  Hopefully by noon, I should know the
answer.

Ed
  ----- Original Message -----
  From: Paul
  To: Rotary motors in aircraft
  Sent: Monday, April 11, 2005 10:54 PM
  Subject: [FlyRotary] Re: Latest on the Motor Trouble


  Hey, Ed....so sorry to hear about your engine misfortune (as well as the
washing machine).  Do you have an air cleaner?  Is there any possiblity your
prop could have blown loose rock/pebbles or FOD into your intake?  Obviously
you will find out soon...just speculating and curious about any filter or
screen you may have on your intake system. Good luck with the engine
rebuild....we will miss your flying reports for a while, but hopefully just
for a short while.  Paul Conner

    ----- Original Message -----
    From: Ed Anderson
    To: Rotary motors in aircraft
    Sent: Monday, April 11, 2005 6:57 PM
    Subject: [FlyRotary] Latest on the Motor Trouble


    Latest status on the engine problem:

    Unfortunately a breakdown in one of the households most important
appliances ( in the wife's view), i.e. - the washing machine precluded me
getting the engine unbuttoned today.  Got as far as getting the flywheel nut
off when got side tracked.

    However, here are some interesting tidbits.  Al told me he could not
find an NGK B9EQV - odd I thought- since I purchased some.  Well when I
opened up the tool box there as plain as day was B9EGV - the CORRECT PLUG -
I am beginning to feel like I am in the twilight zone.  All four -all are
the B9EGV!

    So the right plug - so how come the problem or was it all an figment of
my troubled mind?

    No figment about the problem, I could better examine the apex seals
through the exhaust with a bright light.  I found one apex seal shattered
into three pieces, one stuck down as if springs are broken and one which
appears to move normally in its slot, but has nicks.  Well as we all know
when two of the apex seals are gone on a rotor they might as well all three
be gone.

    Now here is where it gets a bit more spooky - I took one of the B9EGV
plugs and screw them into an 86 NA rotor housing (thanks for the suggestion,
George - down under) I have laying around.  I then measured from the inside
of the housing to the ground electrode of the plug - hold onto your hats -
it measured 7.5 mm!  I could be off by a mm but certainly places the
electrode no where close to the chamber (relative speaking).

    So either the 91 turbo housings (will find out tomorrow) have shorter
sparkplug holes OR the plugs had nothing to do with the problem.  Possibly
some other FOD item - but I use no nuts or screws any place in the induction
system that would cause them to fall off into the runners.
    I've already reported that the next most likely candidate - pieces of
the plastic plenum were a negative as all pieces are still in place.

    I really hate to end the day without getting the bottom of this problem,
but just too beat to tackle it.  Sitting here in front of the computer with
a cool brew - which is something I don't ever recall doing before (not the
drinking, and not the computer - but both together!)

    I am taking photos as I disassemble the engine.  It took me 15 minutes
once I had the engine on the work stand to get Tracy's gearbox, damper
plate, flex plate and flywheel nut off.  Next comes the flex plate, my
broken-bolt shield and then the 17 tension bolts (guess I better remember to
put heat shrink on them).

    Anyhow, thanks to all of you who had suggestions, comments or
condolences conveyed to me.  Appreciate them all and I will keep you
informed as the disassembly progresses.


    Ed
    Ed Anderson
    Rv-6A N494BW Rotary Powered
    Matthews, NC
    eanderson@carolina.rr.com


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