X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from aspensprings.uwyo.edu ([129.72.10.32] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTPS id 4487372 for flyrotary@lancaironline.net; Thu, 30 Sep 2010 10:46:39 -0400 Received-SPF: none receiver=logan.com; client-ip=129.72.10.32; envelope-from=SBoese@uwyo.edu Received: from ponyexpress-ht2.uwyo.edu (ponyexpress-ht2.uwyo.edu [10.84.60.209]) by aspensprings.uwyo.edu (8.14.4/8.14.4) with ESMTP id o8UEiHBq028413 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL) for ; Thu, 30 Sep 2010 08:45:59 -0600 (MDT) (envelope-from SBoese@uwyo.edu) Received: from ponyexpress-mb5.uwyo.edu ([fe80::9813:248c:2d68:a28b]) by ponyexpress-ht2 ([10.84.60.209]) with mapi; Thu, 30 Sep 2010 08:45:18 -0600 From: "Steven W. Boese" To: Rotary motors in aircraft Date: Thu, 30 Sep 2010 08:45:17 -0600 Subject: RE: [FlyRotary] SAG from Paducah Thread-Topic: [FlyRotary] SAG from Paducah Thread-Index: ActgqGhB59aVWx69SXOHrM1I0RDz9gAAswrI Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_E1AA3B1AF41D8049B1E3FBD5E225626004E2453FE0ponyexpressmb_" MIME-Version: 1.0 --_000_E1AA3B1AF41D8049B1E3FBD5E225626004E2453FE0ponyexpressmb_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lynn and Bill, Data recorded (including among others: RPM, EGT, coolant temperature, and o= il temperature) in flight under SAG conditions compared to data recorded in= flight under spark plug misfire conditions (by disabling ignition coils) s= uggest that the SAG event is possibly a preignition condition rather than s= park plug misfire due to fouling. Examination of new and used spark plugs indicate that the preignition may o= ccur because of a gradual effective heat range change of the spark plug wit= h continued use as a result of decreasing thermal conductivity of the coppe= r core of the center electrode as well as corrosion between the center elec= trode and the insulator at the insulator tip. The corrosion appears to be = accelerated by the use of leaded fuel compared to the use of 87 octane auto= motive fuel. Steve Boese ________________________________ From: Rotary motors in aircraft [flyrotary@lancaironline.net] On Behalf Of = Lehanover@aol.com [Lehanover@aol.com] Sent: Thursday, September 30, 2010 8:03 AM To: Rotary motors in aircraft Subject: [FlyRotary] SAG from Paducah So what was the new theory on SAG? I cannot make out the writing on the panels in the picture. The picture app= ears to be two center electrodes. Lynn E. Hanover --_000_E1AA3B1AF41D8049B1E3FBD5E225626004E2453FE0ponyexpressmb_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Lynn and Bill,

Data recorded (including among others= : RPM, EGT, coolant temperature, and oil temperature) in flight= under SAG conditions compared to data recorded in flight under s= park plug misfire conditions (by disabling ignition coils) suggest that the SAG event is possibly a preignition condition= rather than spark plug misfire due to fouling.

Examination of new and used spark plugs indicate = that the preignition may occur because of a gradual e= ffective heat range change of the spark plug with continued use as a r= esult of decreasing thermal conductivity of the copper core of the center electrode as well as corrosion between the center = electrode and the insulator at the insulator tip. The corrosion&= nbsp;appears to be accelerated by the use of leaded fuel compared= to the use of 87 octane automotive fuel.

Steve Boese

=

From: Rotary moto= rs in aircraft [flyrotary@lancaironline.net] On Behalf Of Lehanover@aol.com= [Lehanover@aol.com]
Sent: Thursday, September 30, 2010 8:03 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] SAG from Paducah

So what was the new theory on SAG?

I cannot make out the writing on the panels in the picture. The pictur= e appears to be two center electrodes.

Lynn E. Hanover

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