Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 05 Nov 2005 00:08:18 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m24.mx.aol.com ([64.12.137.5] verified) by logan.com (CommuniGate Pro SMTP 5.0) with ESMTP id 815202 for lml@lancaironline.net; Fri, 04 Nov 2005 18:06:11 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.5; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m24.mx.aol.com (mail_out_v38_r6.3.) id q.c8.6b60a319 (25305) for ; Fri, 4 Nov 2005 18:05:20 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Fri, 4 Nov 2005 18:05:19 EST Subject: Re: [LML] Re: Lancair 320 gear problem -- help wanted X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1131145519" X-Mailer: 9.0 Security Edition for Windows sub 5009 X-Spam-Flag: NO -------------------------------1131145519 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 11/4/2005 12:25:00 P.M. Central Standard Time, dryan@gt.rr.com writes: I think the main breaker only pulls power off of the relays through to the motor? I better check. I'm not sure that your pump tests emulate the sequence I probably experienced. Probably not, we just don't have the failed parts to try to figure out exactly what happened. Did you wire the airplane? Is there a circuit diagram or was it wired per the Lancair scheme and you have 2 breakers, one for the motor (50 A) and one for the relays (5 A)? Did you pull only the 50A breaker for some time during flight and not the 5A, that would have caused the intermittent UP relay to remain powered for a long time? First the down press switch would have opened, the gear down long enough for the press to build to open the switch. I would think that this is the more common state, unless there is a leak somewhere? If there was a bad enough leak, the pump would have continued to run. If it was not bad, the pump would be running frequently to re-build the pressure. Second the HP switch is activated, (the down circuit is not powered) and the up circuit is powered. What happens then when the down switch tries to reverse direction? The state of the up pressure switch is irrelevant. If the panel switch was in the gear down position, power could only be directed to the down relay coil thru the down pressure switch. After all, the down pressure switch has no problem when the gear up function is selected after takeoff. If the relays are undamaged, the only way to actually select the wrong relay is thru the panel switch itself or by a short between the wires leading back to the relays (highly improbable). Did your tests follow such a sequence? Not quite, all I demonstrated is that the motor can run unpredictably if both motor circuits are made sequentially and the power remains on. Note that both relays can be closed (conducting electricity to the motor) without regard to the state of the pressure switches if a relay has been damaged. The only other way to actually select the wrong relay is thru the panel switch itself or by a short between the wires leading back to the relays (highly improbable). If the pump was weakly trying to raise the gear, the nose could have remained down and locked because of the 100 lb gas strut. Did that occur (only the mains collapsed)? Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) -------------------------------1131145519 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 11/4/2005 12:25:00 P.M. Central Standard Time,=20 dryan@gt.rr.com writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I think=20 the main breaker only pulls power off of the relays through to the motor?=20= I=20 better check.
I'm not sure that your pump tests emulate the sequence I= =20 probably experienced.

Probably not, we just don't have the failed parts to try to figure out=20 exactly what happened. Did you wire the airplane? Is there a cir= cuit=20 diagram or was it wired per the Lancair scheme and you have 2 breakers, one=20= for=20 the motor (50 A) and one for the relays (5 A)? Did you pull only the 5= 0A=20 breaker for some time during flight and not the 5A, that would have cau= sed=20 the intermittent UP relay to remain powered for a long time?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>

First the down press switch would have opened, the gear d= own=20 long enough for the press to build to open the switch. I would think that=20= this=20 is the more common state, unless there is a leak somewhere?

If there was a bad enough leak, the pump would have continued to run.&n= bsp;=20 If it was not bad, the pump would be running frequently to re-build the=20 pressure.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>

Second the HP switch is activated, (the down circuit is n= ot=20 powered) and the up circuit is powered.
What happens then when the down= =20 switch tries to reverse direction?

The state of the up pressure switch is irrelevant. If the panel sw= itch=20 was in the gear down position, power could only be directed to the down rela= y=20 coil thru the down pressure switch. After all, the down pressure switc= h=20 has no problem when the gear up function is selected after takeoff. If= the=20 relays are undamaged, the only way to actually select the wrong relay is thr= u=20 the panel switch itself or by a short between the wires leading back to the=20 relays (highly improbable).

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>

Did your tests follow such a sequence?

Not quite, all I demonstrated is that the motor can run unpredictably i= f=20 both motor circuits are made sequentially and the power remains on.&nbs= p;=20 Note that both relays can be closed (conducting electricity to the=20 motor) without regard to the state of the pressure switches if a relay=20= has=20 been damaged. The only other way to actually select the wrong relay is= =20 thru the panel switch itself or by a short between the wires leading back to= the=20 relays (highly improbable).

If the pump was weakly trying to raise the gear, the nose could have=20 remained down and locked because of the 100 lb gas strut. Did that occ= ur=20 (only the mains collapsed)?

Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)

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