REFLECTOR: Reflector Digest, Vol 77, Issue 41 - Door open sensors

Sun Aug 7 09:06:01 CDT 2011

Geoff:

You should absolutely have door open sensors and make a check of the light and feeling each door handle your final pre-takeoff check.  The microswitch for the door sensor is typically mounted below one of the receiving tubes in a lower door latch. You then use a spacer made from a section of venetian blind rod (really) to have the pin push down to activate the microswitch when the door is latched. I have a door open annunciator light right at the top of my panel. 

Since the microswitches are at the bottom of the door and run through the duct, there is no wire flexing. I have detailed pictures of the install on my blog. If you need more info, just email me.

Mark
On Aug 7, 2011, at 9:46 AM, reflector-request at tvbf.org wrote:

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> Today's Topics:
> 
>   1. Re:  Nose Gear Microswitch (Michael Watson)
>   2. Re:  Nose Gear Microswitch (aminetech at bluefrog.com)
>   3.  Door lock microswitch wiring (Geoff Gerhardt)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Sat, 6 Aug 2011 20:47:52 -0400
> From: Michael Watson <mikewatsspg at gmail.com>
> Subject: Re: REFLECTOR: Nose Gear Microswitch
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Message-ID:
> 	<CAPgogjOFRHied_f5KSCvfpBiz3uwoi7Z+biWCkPgEAsn_6oObQ at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Hi John,
> 
> The switch is closed when the light is on. 12 volts is supplied to the
> switch through the lamp, closing the switch (gear down and locked) completes
> the
> circuit to ground turning on the lamp.  The test button acts as a ground for
> all 3 lamps. Since that works, I'd say you have bad (intermittent) grounds
> to
> the switch connections.
> 
> BTW: Don't you carry a 12" metal rod to slide through the keel under the
> nose wheel shocks. It prevents a collapse if the over center is not locked,
> or the
> Tower tells you that the gear is down but the light is off.
> 
> Good Luck,
> 
> On Sat, Aug 6, 2011 at 12:51 PM, <aminetech at bluefrog.com> wrote:
> 
>> After lowering my gear for landing a few days ago, the nose gear indicator
>> light did not come on.  I asked the tower to check and he said the gear was
>> down, but he had no way to tell if it was all the way down.  I retracted and
>> went around.  The sun was on the panel during final.  Downwind I lowered the
>> gear and with the sun gone I could see that the nose light was dimly lit, so
>> I decided to take a chance.  On short final the gear warning light came on
>> (not the nose light, but a separate light that comes on if either the nose
>> or mains are not down), so I held my breath and was relieved when all was
>> OK.  I had recently adjusted the nose gear and switch.  I did it with the
>> normal weight on the nose gear.  I thought that maybe the overcenter linkage
>> might move down a bit with no weight, so I checked and that was the case.
>> So I adjusted the switch to compensate for this.  When I checked the lights,
>> the nose gear light was on, but 2 main gear lights were out.  I pressed the
>> test button and all 3 came on.  When I released it, they all stayed on.  So
>> I replaced the keel cover and checked the lights again.  This time the nose
>> gear light was out.  It came on with the test button, but went back out when
>> I released it.  I'm going to check the microswitch, although I think it's
>> OK.  Is the switch circuit open or closed when the green light is on?  Any
>> ideas of what else to check?
>> 
>> Thanks,
>> 
>> John
>> 
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> 
> 
> 
> -- 
> Mike W.
> 1997 Velocity Elite RG
> Franklin /IVO Electric CS
> Dual GRT EFIS HX Synthetic Vision
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> ------------------------------
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> Message: 2
> Date: Sat, 6 Aug 2011 19:06:14 -0700
> From: <aminetech at bluefrog.com>
> Subject: Re: REFLECTOR: Nose Gear Microswitch
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Message-ID: <20110806190614.96E9F49F at resin06.mta.everyone.net>
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> Message: 3
> Date: Sun, 7 Aug 2011 09:37:51 -0400
> From: Geoff Gerhardt <geoff.gerhardt at gmail.com>
> Subject: REFLECTOR: Door lock microswitch wiring
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Message-ID:
> 	<CAHd2h4LPXsZ_pLT3Q6XdC-7scxq=MwhFa6q2G6Guh9a1dPoXDw at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Folks,
> 
> I want to put microswitches in the door to detect the lock plunger
> position.  I will wire this into my annunciator panel which has an audible
> alarm.  But, I'm wondering if anyone else has wired their door open sensors
> inside the door as I'm interested in seeing how you ran the wires.  I'm
> concerned about fatigue of the wires having to flex every time the door
> opens/closes.  At Oshkosh, I saw that Lancairs have some nice plunger-type
> connectors on their doors (see attached).  I found the manufacturer for
> these and was considering using one.
> 
> I remember a year or so ago, after that tragic crash due to a door open,
> there was discussion about this.  Anyone else putting door-open sensors in
> the doors?
> 
> Thanks.
> 
> Geoff
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> End of Reflector Digest, Vol 77, Issue 41
> *****************************************