X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 01 Jan 2011 19:29:03 -0500 Message-ID: X-Original-Return-Path: Received: from smtp1.av-mx.com ([137.118.16.57] verified) by logan.com (CommuniGate Pro SMTP 5.3.11) with ESMTP id 4660201 for lml@lancaironline.net; Fri, 31 Dec 2010 12:38:50 -0500 Received-SPF: pass receiver=logan.com; client-ip=137.118.16.57; envelope-from=pinetownd@volcano.net Received: from DennisPC (unknown [65.165.166.43]) (Authenticated sender: pinetownd@volcano.net) by smtp1.av-mx.com (Postfix) with ESMTP id 2493A291994 for ; Fri, 31 Dec 2010 12:38:14 -0500 (EST) X-Original-Message-ID: <75846CB0F370432C8B7FB72AE2615BC4@DennisPC> From: "Dennis Johnson" X-Original-To: "Lancair Mailing List" References: In-Reply-To: Subject: Re: [LML] Re: P-STATc? X-Original-Date: Fri, 31 Dec 2010 09:38:21 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0500_01CBA8CE.76970850" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18263 This is a multi-part message in MIME format. ------=_NextPart_000_0500_01CBA8CE.76970850 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Re: [LML] P-STATc?Hi Ross, P-static is a meteorological phenomenon that requires specific weather = conditions. I don't know about your typical weather in South Africa, = but I wouldn't expect you'd have P-static issues on nearly every flight, = beginning on takeoff. Particularly on an airplane not known to have = significant P-static problems. If it were me, I'd look to other things = before electrically bonding airframe parts. =20 Have you tried swapping out the GPS antenna and the antenna cable? = Anybody near you with the same unit you could swap out for a test? =20 If it's only the GPS part of the component, and only one GPS receiver, = I'd look to the antenna and the coax. =20 You might post this question on Bob Nuckolls' AeroElectric newsgroup at: = http://www.matronics.com/Navigator?AeroElectric-List Someone there will likely give you a logical troubleshooting sequence = that will minimize replacement of good parts while you're closing in on = the problem. =20 Dennis Dennis The loss of the GPS signal is as regular as clockwork. Sometimes as = the aircraft lifts off the ground it's gone. Initially I thought it was = the gear pump but sometimes it goes well after gear up. I have = considered that I use a 28v system but MGL assures me that its equipment = can take the voltage. Nonetheless I tried a voltage converter to 14v and = still the GPS signal was lost. Then I smoothed out the input voltage = using a capacitor in an attempt to eliminate voltage spikes. Still lost = the signal.=20 Nothing else seems to be affected within the EFIS or the other = avionics, which only adds to the mystery. Thus, I am led to the idea of P-STAT. Is there perhaps a momentary = electrical discharge into the system that disrupts the GPS. If so why = only the one GPS and why none of the other equipment? The Tru Trak AP is = rock solid using the secondary GPS; the comms are rock solid; as is the = transponder. BTW in answer to another list member, all ground connections have been = checked and are good. All very frustrating. Ross=20 On 2010/12/30 4:21 AM, "Dennis Johnson" wrote: Hi Ross, =20 There are many, many Legacies flying without P-static problems = disabling their avionics. Before I went to a lot of trouble = electrically bonding parts of the airframe, I'd try to determine how = your Legacy is different from the others. And I'd make sure all the = electrical grounds are solidly connected. =20 =20 Do you have any indication that P-static is a frequent problem in = your airplane? Is anything except the GPS function of your MGL Voyager = affected? I once picked up enough static charge that what little hair I = have on my head stood straight up, towards the charged canopy. It = didn't cause a problem with any of the avionics, though. =20 Dennis =20 =20 ------=_NextPart_000_0500_01CBA8CE.76970850 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Re: [LML] P-STATc?
Hi Ross,
 
P-static is a meteorological phenomenon that requires specific = weather=20 conditions.  I don't know about your typical weather in South = Africa, but I=20 wouldn't expect you'd have P-static issues on nearly every flight, = beginning on=20 takeoff.  Particularly on an airplane not known to have significant = P-static problems.  If it were me, I'd look to other things before=20 electrically bonding airframe parts. 
 
Have you tried swapping out the GPS antenna and the antenna = cable? =20 Anybody near you with the same unit you could swap out for a test?  =
 
If it's only the GPS part of the component, and only one GPS = receiver, I'd=20 look to the antenna and the coax.   
 
You might post this question on Bob Nuckolls' AeroElectric = newsgroup=20 at: 
http://www.= matronics.com/Navigator?AeroElectric-List
 
Someone there will likely give you a logical troubleshooting = sequence that=20 will minimize replacement of good parts while you're closing in on the=20 problem. 
 
Dennis
 

 
Dennis

The loss of the GPS signal is = as regular=20 as clockwork. Sometimes as the aircraft lifts off the ground it=92s = gone.=20 Initially I thought it was the gear pump but sometimes it goes well = after gear=20 up. I have considered that I use a 28v system but MGL assures me that = its=20 equipment can take the voltage. Nonetheless I tried a voltage = converter to 14v=20 and still the GPS signal was lost. Then I smoothed out the input = voltage using=20 a capacitor in an attempt to eliminate voltage spikes. Still lost the = signal.=20

Nothing else seems to be affected within the EFIS or the =  other=20 avionics, which only adds to the mystery.

Thus, I am led to the = idea of=20 P-STAT. Is there perhaps a momentary electrical discharge into the = system that=20 disrupts the GPS. If so why only the one GPS and why none of the other = equipment? The Tru Trak AP is rock solid using the secondary GPS; the = comms=20 are rock solid; as is the transponder.

BTW in answer to another = list=20 member, all ground connections have been checked and are = good.

All very=20 frustrating.

Ross


On 2010/12/30 4:21 AM, "Dennis = Johnson"=20 <pinetownd@volcano.net>=20 wrote:
Hi=20 Ross,
 
There are many, many Legacies flying without = P-static=20 problems disabling their avionics.  Before I went to a lot of = trouble=20 electrically bonding parts of the airframe, I'd try to determine how = your=20 Legacy is different from the others.  And I'd make sure all the = electrical grounds are solidly connected.  
 
Do you = have=20 any indication that P-static is a frequent problem in your airplane? =  Is anything except the GPS function of your MGL Voyager = affected?=20  I once picked up enough static charge that what little hair I = have on=20 my head stood straight up, towards the charged canopy.  It = didn't cause=20 a problem with any of the avionics,=20 = though.
 
Dennis
 
 

------=_NextPart_000_0500_01CBA8CE.76970850--