AeroElectric-List Digest Archive

Tue 04/28/15


Total Messages Posted: 9



Today's Message Index:
----------------------
 
     1. 09:13 AM - Re: Starter Solenoid behavior with low Battery (racerjerry)
     2. 09:46 AM - Re: Connector kit for transponder Narco AT 50 (DANIEL PELLETIER)
     3. 11:37 AM - Re: Starter Solenoid behavior with low Battery (Robert L. Nuckolls, III)
     4. 12:14 PM - Re: Re: Starter Solenoid behavior with low Battery (Robert L. Nuckolls, III)
     5. 01:46 PM - Re: Connector kit for transponder Narco AT 50 (Gordon Parker)
     6. 03:25 PM - Re: Starter Solenoid behavior with low Battery (John Morgensen)
     7. 03:50 PM - Flexible Wire for Pull Out Fuse Tray? (Valin & Allyson Thorn)
     8. 05:48 PM - Re: Starter Solenoid behavior with low Battery (John Morgensen)
     9. 07:09 PM - Re: Starter Solenoid behavior with low Battery (Radioflyer)
 
 
 


Message 1


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    Time: 09:13:12 AM PST US
    Subject: Re: Starter Solenoid behavior with low Battery
    From: "racerjerry" <gki@suffolk.lib.ny.us>
    Cessna Pilots Association (CPA) has recently uncovered a common error where starter contactors are sometimes installed upside down and where the weight of the plunger is working against plunger return spring. Contactors should always be installed with the case swaged lip facing DOWN. Terminal Studs should be nearer the bottom of the contactor, rather than the top. Unfortunately, some new contactors are appearing with labels inverted, which adds to the problem. Even with the case lip facing down, CPA suggests adding sealant around the case perimeter at the lip to keep moisture out. Ref: CPA Magazine, April 2015, p.47 -------- Jerry King Read this topic online here: http://forums.matronics.com/viewtopic.php?p=441456#441456


    Message 2


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    Time: 09:46:37 AM PST US
    Subject: Re: Connector kit for transponder Narco AT 50
    From: DANIEL PELLETIER <pelletie1959@me.com>
    Thanks ! Envoy de mon iPad > Le 2015-04-27 21:41, Chuck Birdsall <cbirdsall6@cox.net> a crit : > > > You might give lane-pilot.com a try. > > He doesn't list the connecter online but if you send him a note he may have a serviceable used one. He does carry the pins. > > Chuck > > On Apr 27, 2015, at 20:14, DANIEL PELLETIER <pelletie1959@me.com> wrote: > > > I'm looking for the 18 pins connector And Molex terminals and I don't find any place to buy it. > > A suggestion maybe. > > Daniel Pelletier > > > > > > > > >


    Message 3


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    Time: 11:37:28 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Starter Solenoid behavior with low Battery
    At 19:26 2015-04-27, you wrote: Recently my battery fell below 11 volts and so it could not provide enough power to completely turn over my engine. What surprised me more than the low battery was that after switching off my master and then switching it back on again, the starter attempted to turn the engine. Wow, the master isn't supposed to control the starter solenoid! After charging the battery, the master and starter switches returned to normal operation and the engine started perfectly many times. All was good and I eventually figured out why my battery discharged. However, that still left me wondering how the master switch could possibly activate the starter solenoid without my pushing the start switch. My theory is that the low voltage only partially (weekly) engaged the starter solenoid spring and therefore the spring didn't exert full force to open the solenoid after it was de-energized. I'm not yet ready to conclude that the starter solenoid is actually defective. Anybody also experienced this? Millions of times over the history of vehicular DC power systems not the least of which are airplanes. Contactors will perform as advertised only if coil currents are maintained at or above minimums required for that performance. With a depleted battery, the voltage is low to begin with . . . the internal resistance is also high . . . meaning that the voltage drops still lower when even moderately loaded. This condition increases the probability of starter contactor STICKING by several orders of magnitude. Contactos all have one characteristic in common, they BOUNCE. Some worse than others but none are zero. The designs that come very close to zero are those specifically designed for starter control service. Very light moving contacts. Lots of closure pressure. Small contact area. Emacs! These contacts have hundreds of start cycles on them with what was probably a healthy battery. Drop the battery to 10% capacity . . . the contactor will close but it's going to burn on each bounce and perhaps stick. If battery voltage is not 12.5 volts or more with the master switch just closed, be cognizant of the risk for contactor sticking that goes up exponentially as battery condition goes lower. Your starter contactor is probably fine but suffered an unrealistic expectations event. Bob . . .


    Message 4


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    Time: 12:14:46 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Starter Solenoid behavior with low Battery
    At 11:11 2015-04-28, you wrote: Cessna Pilots Association (CPA) has recently uncovered a common error where starter contactors are sometimes installed upside down and where the weight of the plunger is working against plunger return spring. Contactors should always be installed with the case swaged lip facing DOWN. Terminal Studs should be nearer the bottom of the contactor, rather than the top. Unfortunately, some new contactors are appearing with labels inverted, which adds to the problem. Even with the case lip facing down, CPA suggests adding sealant around the case perimeter at the lip to keep moisture out. Ref: CPA Magazine, April 2015, p.47 Good grief . . . is that canard still circulating? That was investigated several times at Cessna by teams that never seemed to know what the other teams had discovered . . . with no foundation whatsoever laid for the assertions in the CPA article. First, GRAVITY has nothing to do with the performance of ANY relay or contactor I've ever encountered with ONE exception. Back in my railroading days, a signals guy I met showed me some antique signal relays he had collected over the years. Railroad signal equipment remote from AC mains was battery powered. Battery capacity was sufficient for months of operation between charges . . . but signal crews would change out or recharge batteries at conservative intervals. Even so, railroad signals designers had the art of FMEA down decades before anybody bolted a battery to an airplane. Did you know that crossing gates are HELD UP with power? Not much . . . but they're carefully overbalanced such that loss of power drops the gate. Some relays were built without springs and depended on gravity for motion in the de-energized state. This simplified design by eliminating springs. The so called intermittent duty, whisky barrel contactors . . . Emacs! were never designed for starter motor service. Power winch, hydraulic lift gates, etc, yes. But starter motors . . . not so much. The problem got worse when the TC guys starting bolding PM motor starters to their products. Starter inrush currents went up and the massive, copper ring that served as movable contact Emacs! is bouncy to the extreme. There WERE some orientation issues with these contactors but it had nothing to do with gravity. When Cessna went to the floating cowl way back when, rain running down the firewall of a sun-soaked airplane sometimes splashed a contactor body which cooled and sucked in moisture under the crimped-but-not-sealed closure cap. Moisture sucked in as liquid had to escape as a gas during atmospheric variations in pressure. Needless to say, the humidity inside the contactor was 100% and guess what? Emacs! Things got kind of cruddy inside . . . Emacs! There was a ABORTIVE fix tried wherein all contactors were 'sealed' around the terminals and the crimped cap. The results were predictable. Failure rates went down slightly but since the sealing was not hermetic, liquid was still sucked in and vapor exchange went down further. The most effective FIX was to mount the contactor cap-down and drill a tiny 'drain hole' in the center of the cap. Actually, the hole served both as a vent to reduce that sucking tendencies as well as a more reliable exit strategy for any liquid that would pool there. Bottom line is that the whisky barrel contactor has always been a poor performer as a starter contactor 'Better gravity' won't help and uckum-yucky over the openings is useless. The car companies figured that out decades ago. Bob . . .


    Message 5


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    Time: 01:46:10 PM PST US
    Subject: Re: Connector kit for transponder Narco AT 50
    From: Gordon Parker <gptailwind@gmail.com>
    STEINAIR ALSO HAS BOTH On Tue, Apr 28, 2015 at 9:45 AM, DANIEL PELLETIER <pelletie1959@me.com> wrote: > pelletie1959@me.com> > > Thanks ! > > Envoy=C3=A9 de mon iPad > > > Le 2015-04-27 =C3- 21:41, Chuck Birdsall <cbirdsall6@cox.net> a =C3 =A9crit : > > > cbirdsall6@cox.net> > > > > You might give lane-pilot.com a try. > > > > He doesn't list the connecter online but if you send him a note he may > have a serviceable used one. He does carry the pins. > > > > Chuck > > > > On Apr 27, 2015, at 20:14, DANIEL PELLETIER <pelletie1959@me.com> wrote : > > > pelletie1959@me.com> > > > > I'm looking for the 18 pins connector And Molex terminals and I don't > find any place to buy it. > > > > A suggestion maybe. > > > > Daniel Pelletier > > > > > > > > > > > > > > > > > > > > =========== =========== =========== =========== > >


    Message 6


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    Time: 03:25:56 PM PST US
    From: John Morgensen <john@morgensen.com>
    Subject: Re: Starter Solenoid behavior with low Battery


    Message 7


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    Time: 03:50:13 PM PST US
    From: "Valin & Allyson Thorn" <thorn@starflight.aero>
    Subject: Flexible Wire for Pull Out Fuse Tray?
    Hello Bob, Thanks again for all your help over the years of our (wife and my) Lancair Legacy project. In our electrical system design, we've gone with a pull-out fuse tray that is on the right side of the instrument panel. It's about 4 " tall, 2" wide, 24" long and uses blade fuses that light up when they've blown. All the fuse blocks are easily visible to the pilot when the tray is pulled out. We chose this solution because of its simplicity and minimum real estate on the Legacy's small instrument panel. In its implementation, though, I'm a bit concerned with the fatigue life of the thick wires running to it with the tray being pulled out and in for each flight with before takeoff checks. The MIL-W-22759 wire in these gauges is fairly stiff. There are several since the diodes between buses are on the avionics shelf because of fuse tray space limitations. Is there a very flexible 10 and 8 AWG wire that we could use for the connections between our fuse tray and avionics shelf, that can better handle the fuse tray motion/flexing than the MIL-W-22759, and is air worthy? Thanks, Valin Thorn Lancair Legacy Project Colorado


    Message 8


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    Time: 05:48:22 PM PST US
    From: John Morgensen <john@morgensen.com>
    Subject: Re: Starter Solenoid behavior with low Battery
    Re-sending: What about the proposal to eliminate the starter contactor? I am looking at the Skytec dagram here: > http://www.skytecair.com/Wiring_diag.htm The starter barely gets 10 volts after the master contactor and the starter contactor in series. By eliminating the starter contactor, you would have a hot wire to the starter whenever the master is on. Is this a good idea or suicide? john On 4/28/2015 11:31 AM, Robert L. Nuckolls, III wrote: > At 19:26 2015-04-27, you wrote: > <skyeyecorp@airpost.net> > > Recently my battery fell below 11 volts and so it could not provide > enough power to completely turn over my engine. What surprised me more > than the low battery was that after switching off my master and then > switching it back on again, the starter attempted to turn the engine. > Wow, the master isn't supposed to control the starter solenoid! > > After charging the battery, the master and starter switches returned > to normal operation and the engine started perfectly many times. All > was good and I eventually figured out why my battery discharged. > However, that still left me wondering how the master switch could > possibly activate the starter solenoid without my pushing the start > switch. My theory is that the low voltage only partially (weekly) > engaged the starter solenoid spring and therefore the spring didn't > exert full force to open the solenoid after it was de-energized. I'm > not yet ready to conclude that the starter solenoid is actually > defective. Anybody also experienced this?


    Message 9


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    Time: 07:09:42 PM PST US
    Subject: Re: Starter Solenoid behavior with low Battery
    From: "Radioflyer" <skyeyecorp@airpost.net>
    Ok, I was worried there for a while thinking that either I burned up my starter solenoid contacts and/or that it was mounted upside down. Like I said in my original post, now that battery voltage is normal, the starter solenoid is operating perfectly. However, I agree that I probably abused it with the low battery situation, probably shortening its expected service life, and I will be on the look out for future problems with it. --Jose Read this topic online here: http://forums.matronics.com/viewtopic.php?p=441477#441477




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