Return-Path: Sender: (Marvin Kaye) To: lml Date: Fri, 09 May 2003 14:32:29 -0400 Message-ID: X-Original-Return-Path: Received: from [63.150.227.63] (HELO admsmxs2usr10.ad.jocoks.com) by logan.com (CommuniGate Pro SMTP 4.1b6) with ESMTP id 2342000 for lml@lancaironline.net; Fri, 09 May 2003 14:31:55 -0400 X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C31659.4134A53E" Subject: [LML] Moondog's RPM & Hydraulic Mysteries Solved! X-Original-Date: Fri, 9 May 2003 13:31:49 -0500 X-Original-Message-ID: <4B9B1B1833408C40AE2F14A881F276F610B330@admsmxs2usr10.ad.jocoks.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [LML] Moondog's RPM & Hydraulic Mysteries Solved! Thread-Index: AcMWWUD37urOI5WkQtu5pThgy5aXdQ== From: "Metcalfe, Lee, AIR" X-Original-To: This is a multi-part message in MIME format. ------_=_NextPart_001_01C31659.4134A53E Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable In a blitz to get my plane ready to win at SFQ, I finally got my two mysteries resolved. =20 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! =20 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! =20 Looking forward to meeting everyone at SFQ! =20 Lee "Moondog" Metcalfe N320WH - LNC2 - IO-320 - 480 hrs. - Kansas City (IXD) ------_=_NextPart_001_01C31659.4134A53E Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
In a = blitz to get my=20 plane ready to win at SFQ, I finally got my two mysteries=20 resolved.
 
RPM = (http://lan= caironline.net/lists/lml/Message/21130.html)=20 - This turned out to be much ado (and expense) over (almost) = nothing.  For=20 the first time since the problem emerged about 20 flilght hours ago, we = went up=20 with one of those hand-held digital tachs.  It turns out the = problem was=20 not with actual RPM control.  It was the indication that was = wrong! =20 We had the tach checked as one of the first items of diagnosis about 19 = hrs.=20 ago.  It bench-tested +/- 25 RPM, so we presumed during all = subsequent=20 diagnostic efforts that it was telling us the truth.  Wrong!  = The=20 hand-held tach showed we were indeed getting 2700 at the full increase = setting=20 of the prop control, even though the tach was reading 2500.  We did = the=20 climbs and descents and got the same INDICATED RPM behavior I've talked = about in=20 previous posts, however, the hand-held tach showed the indication was = wrong and=20 the RPM was behaving exactly as it should.  It appears that = whenever the=20 engine is under heavy load (i.e. low airspeed/high power) the RPM as = indicated=20 on the installed mechanical tach is being dragged down by about 200=20 RPM.  My A&P suspects that the RPM drive cable is binding = when the=20 engine torques in the mount under load.  I checked with the = other=20 A&P (different FBO) who installed my EDM-700, and he said he had to=20 "slightly" reroute the tach drive cable when he was installing the EDM = head in=20 the panel.  GRRRR!  I don't know why my current A&P didn't = check=20 the RPM sooner with the hand-held tach!  We'll be having a serious = talk=20 about the 10 or 12 hours they've already billed me for diagnostic time = and the=20 $600 governor overhaul that I didn't need!
 
Hydraulics (http://lan= caironline.net/lists/lml/Message/21378.html)=20 - Since I have started flying regularly again, the long pump run when = first=20 powering up has gone back to the usual chirp.  Maybe some air in = the system=20 after sitting for 6 months?  For the first time since I bought the = plane I=20 put it up on jacks and swung the gear.  It went up in the same = sequence=20 several of you described to me.  I used the dump valve to lower it=20 and everything came down as it should, except the left main = wouldn't quite=20 get to the locked position on it's own.  Shot a little lube at all = the=20 movement points and that fixed it.  Closed the dump valve, pumped = the gear=20 back up and let it sit for about 12 hours.  The gear didn't droop = at all=20 (woohoo!).  Checked the nose gear air strut and it seems good and=20 strong.  Went flying and did the emergency drop check.  The = nose gear=20 locked down a lot quicker than it did the last time I did the in-flight=20 check.  Hmmm.  What have I changed since then?  What = would cause=20 the nose gear to come up slower and extend faster?  Aha!  I = had=20 removed the landing light (big ole 4" job) that had been mounted on the = nose=20 strut about 4" up from the end of the strut.  I had removed a 12 = sq. in.=20 flat plate equivalent on about a 12" arm that was resisting extension = and=20 assisting retraction!  Mystery solved!
 
Looking forward to=20 meeting everyone at SFQ!
 
Lee = "Moondog"=20 Metcalfe
N320WH = - LNC2 -=20 IO-320 - 480 hrs. - Kansas City (IXD)
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