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Message
In a blitz to get my
plane ready to win at SFQ, I finally got my two mysteries
resolved.
RPM (http://lancaironline.net/lists/lml/Message/21130.html)
- This turned out to be much ado (and expense) over (almost) nothing. For
the first time since the problem emerged about 20 flilght hours ago, we went up
with one of those hand-held digital tachs. It turns out the problem was
not with actual RPM control. It was the indication that was wrong!
We had the tach checked as one of the first items of diagnosis about 19 hrs.
ago. It bench-tested +/- 25 RPM, so we presumed during all subsequent
diagnostic efforts that it was telling us the truth. Wrong! The
hand-held tach showed we were indeed getting 2700 at the full increase setting
of the prop control, even though the tach was reading 2500. We did the
climbs and descents and got the same INDICATED RPM behavior I've talked about in
previous posts, however, the hand-held tach showed the indication was wrong and
the RPM was behaving exactly as it should. It appears that whenever the
engine is under heavy load (i.e. low airspeed/high power) the RPM as indicated
on the installed mechanical tach is being dragged down by about 200
RPM. My A&P suspects that the RPM drive cable is binding when the
engine torques in the mount under load. I checked with the other
A&P (different FBO) who installed my EDM-700, and he said he had to
"slightly" reroute the tach drive cable when he was installing the EDM head in
the panel. GRRRR! I don't know why my current A&P didn't check
the RPM sooner with the hand-held tach! We'll be having a serious talk
about the 10 or 12 hours they've already billed me for diagnostic time and the
$600 governor overhaul that I didn't need!
Hydraulics (http://lancaironline.net/lists/lml/Message/21378.html)
- Since I have started flying regularly again, the long pump run when first
powering up has gone back to the usual chirp. Maybe some air in the system
after sitting for 6 months? For the first time since I bought the plane I
put it up on jacks and swung the gear. It went up in the same sequence
several of you described to me. I used the dump valve to lower it
and everything came down as it should, except the left main wouldn't quite
get to the locked position on it's own. Shot a little lube at all the
movement points and that fixed it. Closed the dump valve, pumped the gear
back up and let it sit for about 12 hours. The gear didn't droop at all
(woohoo!). Checked the nose gear air strut and it seems good and
strong. Went flying and did the emergency drop check. The nose gear
locked down a lot quicker than it did the last time I did the in-flight
check. Hmmm. What have I changed since then? What would cause
the nose gear to come up slower and extend faster? Aha! I had
removed the landing light (big ole 4" job) that had been mounted on the nose
strut about 4" up from the end of the strut. I had removed a 12 sq. in.
flat plate equivalent on about a 12" arm that was resisting extension and
assisting retraction! Mystery solved!
Looking forward to
meeting everyone at SFQ!
Lee "Moondog"
Metcalfe
N320WH - LNC2 -
IO-320 - 480 hrs. - Kansas City (IXD)
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