X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 09 Jan 2011 17:55:25 -0500 Message-ID: X-Original-Return-Path: Received: from relay02.smp.mweb.co.za ([196.28.80.22] verified) by logan.com (CommuniGate Pro SMTP 5.3.11) with ESMTPS id 4668781 for lml@lancaironline.net; Sun, 09 Jan 2011 06:02:20 -0500 Received-SPF: none receiver=logan.com; client-ip=196.28.80.22; envelope-from=rossl@mweb.co.za Received: from 41-135-46-131.dsl.mweb.co.za ([41.135.46.131] helo=[192.168.2.2]) by relay02.smp.mweb.co.za with esmtp (Exim 4.72) id 1Pbt1h-000L2a-1F; Sun, 09 Jan 2011 13:01:42 +0200 User-Agent: Microsoft-Entourage/12.23.0.091001 X-Original-Date: Sun, 09 Jan 2011 13:01:31 +0200 Subject: Re: [LML] Re: P-STATc? From: Ross Leighton X-Original-To: Dennis Johnson , Lancair List X-Original-Message-ID: Thread-Topic: [LML] Re: P-STATc? Thread-Index: Acuv7JIwHlMGI9VA2EWSHLIw47tFYg== In-Reply-To: Mime-version: 1.0 Content-type: multipart/alternative; boundary="B_3377422892_116962" > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3377422892_116962 Content-type: text/plain; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Hi Guys Thanks to all the people who commented and offered opinions and advice. Those of you, Like Dennis, who said that it was unlikely to be Pstatic were absolutely correct. It turns out that the problem was as simple as that I mounted the MGL GPS antennae in the left wing tip and had to have extension leads made to reach the EFIS. One of the gold-plated connections was not insulated and touched the inside surface of the carbon wing skin. Thus causing a double ground and all sorts of problems. Once I had insulated the connector the GPS held signal and in fact I have just returned from a weeks vacation in the aircraft where it was used every day and no further problem= s encountered. BTW on a different note I can report favourable on the Legacy=B9s performance in and out of a gravel strip. My friends farm where we were vacationing has a 2750=B9 gravel strip well rolled and maintained. Field elevation is 1000=B9 and the Legacy took it in its stride. We also did some interesting canyon flying in the early mornings to avoid the heat. Bit of a rush going down some of the wide canyons at 200kts. What a great machine. Regards Ross On 2011/01/02 2:29 AM, "Dennis Johnson" wrote: > Hi Ross, > =20 > 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, beginn= ing > 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? Anybo= dy > 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 > =20 > Someone there will likely give you a logical troubleshooting sequence tha= t > will minimize replacement of good parts while you're closing in on the > problem. =20 > =20 > Dennis >> =20 >> =20 >> =20 >>=20 >> =20 >> Dennis >>=20 >> The loss of the GPS signal is as regular as clockwork. Sometimes as the >> aircraft lifts off the ground it=B9s 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 att= empt >> to eliminate voltage spikes. Still lost the signal. >>=20 >> Nothing else seems to be affected within the EFIS or the other avionic= s, >> which only adds to the mystery. >>=20 >> 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 o= nly >> the one GPS and why none of the other equipment? The Tru Trak AP is roc= k >> solid using the secondary GPS; the comms are rock solid; as is the >> transponder. >>=20 >> BTW in answer to another list member, all ground connections have been >> checked and are good. >>=20 >> All very frustrating. >>=20 >> Ross=20 >>=20 >>=20 >> On 2010/12/30 4:21 AM, "Dennis Johnson" wrote: >>=20 >> =20 >>> Hi Ross, >>> =20 >>> There are many, many Legacies flying without P-static problems disabli= ng >>> their avionics. Before I went to a lot of trouble electrically bondin= g >>> parts of the airframe, I'd try to determine how your Legacy is differe= nt >>> from the others. And I'd make sure all the electrical grounds are sol= idly >>> 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 did= n't >>> cause a problem with any of the avionics, though. >>> =20 >>> Dennis >>> =20 >>> =20 >>>=20 >=20 --B_3377422892_116962 Content-type: text/html; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Re: [LML] Re: P-STATc? Hi Guys

Thanks to all the people who commented and offered opinions and advice. Tho= se of you, Like Dennis, who said that it was unlikely to be Pstatic were abs= olutely correct. It turns out that the problem was as simple as that I mount= ed the MGL GPS antennae in the left wing tip and had to have extension leads= made to reach the EFIS. One of the gold-plated connections was not insulate= d and touched the inside surface of the carbon wing skin. Thus causing a dou= ble ground and all sorts of problems. Once I had insulated the connector the= GPS held signal and in fact I have just returned from a weeks vacation in t= he aircraft where it was used every day and no further problems encountered.=

BTW on a different note I can report favourable on the Legacy’s perfo= rmance in and out of a gravel strip. My friends farm where we were vacationi= ng has a 2750’ gravel strip well rolled and maintained. Field elevatio= n is 1000’ and the Legacy took it in its stride. We also did some inte= resting canyon flying in the early mornings to avoid the heat.  Bit of = a rush going down some of the wide canyons at 200kts. What a great machine. =

Regards

Ross


On 2011/01/02 2:29 AM, "Dennis Johnson" <pinetownd@volcano.net> wrote:

H= i Ross,
 
P-static is a meteorological phenomenon that requires specific weather cond= itions.  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, beginnin= g on takeoff.  Particularly on an airplane not known to have significan= t P-static problems.  If it were me, I'd look to other things before el= ectrically bonding airframe parts.  
 
Have you tried swapping out the GPS antenna and the antenna cable?  An= ybody 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 = look to the antenna and the coax.    
 
You might post this question on Bob Nuckolls' AeroElectric newsgroup at: http://www.m= atronics.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 probl= em.  
 
Dennis
=
 
 

 
Dennis

The loss of the GPS signal is as regular  as clockwork. Sometimes as t= he 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  equipme= nt can take the voltage. Nonetheless I tried a voltage converter to 14v &nbs= p;and still the GPS signal was lost. Then I smoothed out the input voltage u= sing  a capacitor in an attempt to eliminate voltage spikes. Still lost= the signal.  

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 el= ectrical discharge into the system that  disrupts the GPS. If so why on= ly 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 t= he transponder.

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

All very  frustrating.

Ross


On 2010/12/30 4:21 AM, "Dennis Johnson"  <pinetownd@volcano.net>  wrote:

 
H= i  Ross,
 
There are many, many Legacies flying without P-static  problems disabl= ing their avionics.  Before I went to a lot of trouble  electrical= ly 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  electri= cal grounds are solidly connected.  
 
Do you have  any indication that P-static is a frequent problem in you= r airplane?   Is anything except the GPS function of your MGL Voya= ger affected?   I once picked up enough static charge that what li= ttle hair I have on  my head stood straight up, towards the charged can= opy.  It didn't cause  a problem with any of the avionics,  t= hough.
 
Dennis
 
 


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