Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Fri, 12 Dec 2003 15:50:15 -0500 Message-ID: X-Original-Return-Path: Received: from imo-r03.mx.aol.com ([152.163.225.99] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2888160 for lml@lancaironline.net; Fri, 12 Dec 2003 15:14:32 -0500 Received: from Sky2high@aol.com by imo-r03.mx.aol.com (mail_out_v36_r1.1.) id q.3e.38eeb462 (4410) for ; Fri, 12 Dec 2003 15:14:29 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <3e.38eeb462.2d0b7ba4@aol.com> X-Original-Date: Fri, 12 Dec 2003 15:14:28 EST Subject: An A/P Anomaly - Another Attention Getting Event! X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1071260068" X-Mailer: Thailand for Windows sub 280 -------------------------------1071260068 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Just out to make another test flight - let's see how the cleaned up S-Tec 50 servo follows the ARR GPS 27 Approach. Motoring along, I punch the GPSS button, take the A/P from the "ready state" to "on" and immediately hit the HDG button. Whoa! The roll to 40 degrees of bank was unexpected. Snapping off the A/P, I collect my thoughts (not much effort needed for this). I say to myself, "Self, let's just try the wing stablizer." Another exciting roll commences - the other way, even - and no sense that it would stop. With the A/P off again, I move my old collection of thoughts to the little trash can icon. Hmmmm..... Oh, that's right, Yesterday I pulled the turn coordinator (TC) breaker for some unrelated ground checks. Yep, after restoring TC power, the red flag went away, the A/P was recycled and it held the wings rock solid. Wait a second, if the TC gyro is not up to speed, the A/P ready light should never come on and, if power is lost to the TC, the A/P should automatically disconnect. One input to the A/P computer is a voltage (about 8 VDC) representing that the TC gyro tach output is good. Failing the voltage check, the A/P should not come ready or operate. When I can, I will investigate and report why there is voltage on the TC Tach output line when the TC has no power at all. In the meantime, I suggest that those with an S-Tec A/P perform the simple ground check: 1. Pull the breaker for the turn coordinator. 2. Turn on the Master/Avionics sw(s). 3. Switch the A/P to "test". 4. After the internal sequence of A/P checks, if the green "ready" light illuminates, there is a safety problem. Diagnose the cause before serious IFR flight. Jocular IFR flights should also be avoided. Scott Krueger Sky2high@aol.com II-P N92EX IO320 Aurora, IL (KARR) PS Gary, I couldn't just "engine" along. Oh well, one step forward, one step back. "...as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns - the ones we don't know we don't know." D. Rumsfeld -------------------------------1071260068 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Just out to make another test flight - let's see how the cleaned up S-T= ec=20 50 servo follows the ARR GPS 27 Approach. Motoring along, I punch the GPSS=20 button, take the A/P from the "ready state" to "on" and immediately hit the=20= HDG=20 button. Whoa! The roll to 40 degrees of bank was unexpected.&nbs= p;=20 Snapping off the A/P, I collect my thoughts (not much effort needed for= =20 this). I say to myself, "Self, let's just try the wing=20 stablizer." Another exciting roll commences - the other way, even= -=20 and no sense that it would stop. With the A/P off again, I move my old=20 collection of thoughts to the little trash can icon.

Hmmmm..... Oh, that's right, Yesterday I pulled the turn coordina= tor=20 (TC) breaker for some unrelated ground checks. Yep, after restori= ng=20 TC power, the red flag went away, the A/P was recycled and it= =20 held the wings rock solid.

Wait a second, if the TC gyro is not up to speed, the A/P ready light=20 should never come on and, if power is lost to the TC, the A/P should=20 automatically disconnect. One input to the A/P computer is a voltage=20 (about 8 VDC) representing that the TC gyro tach output is good. =20 Failing the voltage check, the A/P should not come ready or operate.

When I can, I will investigate and report why there is voltage on=20= the=20 TC Tach output line when the TC has no power at all.

In the meantime, I suggest that those with an S-Tec A/P perform=20 the simple ground check:

1. Pull the breaker for the turn coordinator.

2. Turn on the Master/Avionics sw(s).

3. Switch the A/P to "test".

4. After the internal sequence of A/P checks, if the green "ready" ligh= t=20 illuminates, there is a safety problem. Diagnose the cause before seri= ous=20 IFR flight. Jocular IFR flights should also be avoided.

Scott=20 Krueger
Sky2high@aol.com
II-P N92EX IO320 Aurora, IL (KARR)

PS Gary, I=20 couldn't just "engine" along. Oh well, one step forward, one step back.

"...as we know, there are known knowns; there are things we kno= w we=20 know. We also know there are known unknowns; that is to say we know there ar= e=20 some things we do not know. But there are also unknown unknowns - the ones w= e=20 don't know we don't know." D. Rumsfeld

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