X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao11.cox.net ([68.230.241.28] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 970263 for flyrotary@lancaironline.net; Sat, 04 Feb 2006 17:56:05 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.28; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao11.cox.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20060204225353.QUWI6244.fed1rmmtao11.cox.net@BigAl> for ; Sat, 4 Feb 2006 17:53:53 -0500 From: "Al Gietzen" To: "Rotary motors in aircraft" Subject: Atkins errors Date: Sat, 4 Feb 2006 14:55:22 -0800 Message-ID: <000001c629de$1470e7a0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C6299B.064DA7A0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C6299B.064DA7A0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Once again I was at a loss for the appropriate expression (@#$%^&%$#$%) after finding that the two larger diameter through-bolts (tension bolt? whatever) on my 20B had not ever been torqued. I had mentioned a while = back that when running my engine on the plane I had noted a small coolant = leak coming from a through-bolt at the bottom of the rear housing. With the = rear engine mount plate and re-drive mounted it was not possible to get a = wrench on it. =20 I was about to begin the process of removing the re-drive, etc. to = replace the seal, when, for whatever reason I grabbed a couple of wrenches to = put on the larger bolt at the top just to check what size it was (21mm). As I = was fitting the wrench onto the head I thought I saw the bolt move. No way. = I flipped the wrnech over and put the box end on the bolt - THE BOLT WAS LOOSE! It took at least a full turn to get to a torque of 25 -30 = ft-lbs. I checked the 17mm bolts - they were fine. After removing the starter and = a couple of the re-drive plate spacer blocks, I was able to check the = other bolts. The bottom 21mm bolt that was leaking was also loose. It took = more than half a turn to get it tight. =20 Best I can guess is that all the smaller bolts were torqued, but whoever = did the job, forgot to tighten the 2 21mm bolts. It is just unbelievable to = me that an "expert" building up an engine for an aircraft could make these errors. =20 I was upset by failed attempts by Atkins on custom exhaust and intakes, = but I rationalized that at least on the engine block he really knew what he = was doing. But later found at least four major errors; =20 1. Installing 9.0 compression rotors in a NA engine instead of 9.7, and then arguing that the lower compression was better. I agree that at = high rpm, 6500+, it won't make any difference; but Mazda test data suggests = about a 4% penalty at my cruise range of 5000 - 5400 rpm. 2. A custom longer oil pickup tube for my deeper pan which was; a) too long to fit in the pan (which he had in his shop), and b) leaked air = around the flange weld so the oil pump would suck air bubbles. 3. A front e-shaft pulley with timing marks that bore no relation to the timing pointer. I guess the because of a stock 20B pulley and a 12A front cover. This took some hours to resolve during the dyno testing. 4. And now the two tension bolts that had never been tightened. =20 I can only hope there will be no further "discoveries". The last time I talked to David (months ago) he mentioned that he was no longer = providing engines for aircraft. Good idea - just too late. He did my engine = about 4 years ago. =20 A couple of questions: Why are two of the bolts larger? What is the = torque spec on these bolts for the 20B? I seem to recall 26-28 ft-lbs. I = can't get a torque wrench on the bolts without removing the re-drive, engine = mount and flywheel, but I have a pretty well calibrated arm. =20 Al =20 =20 =20 =20 ------=_NextPart_000_0001_01C6299B.064DA7A0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Once again I was at a loss for the appropriate = expression (@#$%^&%$#$%) after finding that the two larger diameter through-bolts (tension bolt? = whatever) on my 20B had not ever been torqued.  I had mentioned a while back = that when running my engine on the plane I had noted a small coolant leak = coming from a through-bolt at the bottom of the rear housing.  With the = rear engine mount plate and re-drive mounted it was not possible to get a = wrench on it.

 

I was about to begin the process of removing the = re-drive, etc. to replace the seal, when, for whatever reason I grabbed a couple = of wrenches to put on the larger bolt at the top just to check what size it = was (21mm).  As I was fitting the wrench onto the head I thought I saw = the bolt move.  No way.  I flipped the wrnech over and put the box = end on the bolt – THE BOLT WAS LOOSE!  It took at least a full turn = to get to a torque of 25 -30 ft-lbs.  I checked the 17mm bolts – = they were fine.  After removing the starter and a couple of the re-drive = plate spacer blocks, I was able to check the other bolts.  The bottom = 21mm bolt that was leaking was also loose.  It took more than half a turn to = get it tight.

 

Best I can guess is that all the smaller bolts were = torqued, but whoever did the job, forgot to tighten the 2 21mm bolts.  It is = just unbelievable to me that an “expert” building up an engine for an aircraft = could make these errors.

 

I was upset by failed attempts by Atkins on custom = exhaust and intakes, but I rationalized that at least on the engine block he = really knew what he was doing.  But later found at least four major = errors;

 

  1. Installing 9.0 compression rotors in a NA = engine instead of 9.7, and then arguing that the lower compression was = better.  I agree that at high rpm, 6500+, it won’t make any difference; = but Mazda test data suggests about a 4% penalty at my cruise range of = 5000 – 5400 rpm.
  2. A custom longer oil pickup tube for my deeper = pan which was; a) too long to fit in the pan (which he had in his = shop), and b) leaked air around the flange weld so the oil pump would suck air bubbles.
  3. A front e-shaft pulley with timing marks that = bore no relation to the timing pointer.  I guess the because of a = stock 20B pulley and a 12A front cover.  This took some hours to resolve = during the dyno testing.
  4. And now the two tension bolts that had never = been tightened.

 

I can only hope there will be no further = “discoveries”.  The last time I talked to David (months ago) he mentioned that he = was no longer providing engines for aircraft.  Good idea – just too = late.  He did my engine about 4 years ago.

 

A couple of questions: Why are two of the bolts larger?  What is the torque spec on these bolts for the 20B?  = I seem to recall 26-28 ft-lbs.  I can’t get a torque wrench on the = bolts without removing the re-drive, engine mount and flywheel, but I have a = pretty well calibrated arm.

 

Al

 

 

 

 

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