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P-leads

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john(at)johnkeen.com.au
Guest

Posted: Sat May 13, 2017 11:20 pm Post subject: P-leads

Hi Bob,

I have an engine with the Bendix dual magneto. It came without P-leads, so Iâ€™m wondering whether they are something I can fabricate or if I will need to purchase them complete?



Best regards,

John.

 John Keen

0412 141 833

15 Scott St

Scone NSW Australia 2337

cbirdsall6(at)cox.net
Guest

Posted: Sun May 14, 2017 5:30 pm Post subject: P-leads

John,



You can build your own - but I'm not aware of anyone other than TCM (Continental owns the Bendix magneto line) that makes the individual parts. To get an idea what's involved, the Service Manual for your magneto will be here, listed by model number: 



http://www.continentalmotors.aero/support/maintenance-manuals.aspx#ignition



The p-lead parts are called terminal kits in the manual. The how-to should be in section 9, the parts in section 11. Be sure to watch model number/part numbers and "usable on" codes to make sure you get the right part numbers.



Aircraft Spruce sells the terminal kits for about US$75 each. The kit consists of the nut, stepped bushing, insulator, and a washer.

Aside from a bit of soldering they aren't that difficult to assemble. Care must be taken to keep the overall length of the terminal within the parameters specified. Too long or too short and you may not get good contact.



OR - 



Bogert makes pre-made p-leads for about US$80 each depending on length:



https://bogertaviation.com/collections/p-leads/products/p-leads-d-2000-d-3000-magneto



They're available thru Bogert direct or thru Spruce.  Bendix p-leads come in two varieties (hex nut and round nut) and the round nut variety comes in two different lengths. Watch the video at the bottom of the Bogert web site. Make sure the version you order matches the model number of your magneto.

Regards,



Chuck



---- John Keen <john(at)johnkeen.com.au> wrote: 

 	  Quote: 	
		   Hi Bob,

 

 I have an engine with the Bendix dual magneto. It came without P-leads, so Iâ€™m wondering whether they are something I can fabricate or if I will need to purchase them complete?

 

 Best regards,

 John.

 

 John Keen

 0412 141 833

 15 Scott St

 Scone NSW Australia 2337

nuckolls.bob(at)aeroelect
Guest

Posted: Mon May 15, 2017 6:10 am Post subject: P-leads

At 02:18 AM 5/14/2017, you wrote:

  	  Quote: 	
		  Hi Bob,



 I have an engine with the Bendix dual magneto. It came without P-leads, so Iâ€™m wondering whether they are something I can fabricate or if I will need to purchase them complete? 	


   I have made these things. They're not hard to

   duplicate but you do need a lathe and the

   right taps for the cap threads. I may still

   have a 3/8-32 tap around here somewhere.



   I forget the thread size for the larger cap.

   Didn't need to make that one so didn't

   acquire the tap. The materials are not critical.



   I cut the contact from brass rod, the cap from

   aluminum rod and the insulator from delrin rod.

   All that stuff was laying around and the tap was readily

   available in Wichita so it wasn't a big time-buster

   project.



   I've lost the sketches I made for dimensions. You

   would need to have access to manufactured parts

   to acquire the dimensions. I'll have to check

   with my buddy in K.C. to see if that part is

   still flying on his Mooney.



 

   Bob . . .

john(at)johnkeen.com.au
Guest

Posted: Mon May 15, 2017 4:45 pm Post subject: P-leads

Many thanks to everyone who's replied, fortunately I have access to the materials and original parts as patterns so I think I'll have a go at matching the terminal parts. Pretty sure we'll have a suitable tap here somewhere.

Cheers,

John.



John Keen0412 141 833





On 16 May 2017, at 00:08, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 02:18 AM 5/14/2017, you wrote:

  	  Quote: 	
		  Hi Bob,



 I have an engine with the Bendix dual magneto. It came without P-leads, so Iâ€™m wondering whether they are something I can fabricate or if I will need to purchase them complete? 	


   I have made these things. They're not hard to

   duplicate but you do need a lathe and the

   right taps for the cap threads. I may still

   have a 3/8-32 tap around here somewhere.



   I forget the thread size for the larger cap.

   Didn't need to make that one so didn't

   acquire the tap. The materials are not critical.



   I cut the contact from brass rod, the cap from

   aluminum rod and the insulator from delrin rod.

   All that stuff was laying around and the tap was readily

   available in Wichita so it wasn't a big time-buster

   project.



   I've lost the sketches I made for dimensions. You

   would need to have access to manufactured parts

   to acquire the dimensions. I'll have to check

   with my buddy in K.C. to see if that part is

   still flying on his Mooney.



 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Mon May 15, 2017 6:30 pm Post subject: P-leads

At 07:43 PM 5/15/2017, you wrote:

  	  Quote: 	
		  Many thanks to everyone who's replied, fortunately I have access to the materials and original parts as patterns so I think I'll have a go at matching the terminal parts. Pretty sure we'll have a suitable tap here somewhere. 	


    Good show!  Send us some pix of the

    finished product!



    I got my 3/8-32 off eBay as I recall,

    I think I paid more for it than this



  http://tinyurl.com/lwav9l3



    I think I'm recalling that the larger

    p-lead nut on the dual point

    mag was 7/16-28



 

 

   Bob . . .

pmather

Joined: 17 Sep 2009
Posts: 33

Posted: Tue May 16, 2017 3:25 am Post subject: P-leads

John

 

Iâ€™m flying a TB10 while building. This has a O-360 with the Bendix dual mag. These things are a disaster for maintenance â€“ hugely expensive and parts difficult/impossible to buy

Depending on the state of your build I would seriously look at changing the accessory housing and converting to a normal pair of Slicks. Better redundancy, cheap and easy to maintain and solid reliability.

 

Rgds

 

Peter

 

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of John Keen

Sent: 14 May 2017 08:19

To: aeroelectric-list(at)matronics.com

Subject: P-leads

 

Hi Bob,

 



I have an engine with the Bendix dual magneto. It came without P-leads, so Iâ€™m wondering whether they are something I can fabricate or if I will need to purchase them complete?



 



Best regards,



John.



 

John Keen



0412 141 833



15 Scott St



Scone NSW Australia 2337

nuckolls.bob(at)aeroelect
Guest

Posted: Tue May 16, 2017 6:05 am Post subject: P-leads

At 06:24 AM 5/16/2017, you wrote:

  	  Quote: 	
		  John

  

 Iâ€™m flying a TB10 while building. This has a O-360 with the Bendix dual mag. These things are a disaster for maintenance – hugely expensive and parts difficult/impossible to buy<

 Depending on the state of your build I would seriously look at changing the accessory housing and converting to a normal pair of Slicks. Better redundancy, cheap and easy to maintain and solid reliability.

  

 Rgds

  

 Peter 	


    Another alternative would be E-Mags



  http://tinyurl.com/n5vzcdp



    



 

 

   Bob . . .

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Tue May 16, 2017 12:23 pm Post subject: P-leads

While you may have flown a plane with a dual mag, that is about 

equivalent to a stay with Holiday Inn Express. If it was such a bad 

device, why in the heck were you flying behind something depending on 

it? Why isn't there an AD requiring removal?

Yes, there were some issues with the dual mag when it was first 

introduced, both developmental and caused by mechanics unfamiliar with 

its specific needs. That is way in the past. There are numerous magneto 

shops that do quality overhauls of dual mags and know what is needed. 

PMA parts suppliers make most of the needed replacement parts.

Properly installed and maintained, the dual mag is at least equal to the 

Slicks you suggest, perhaps better in terms of reliability.

There are valid reasons to chose to change to individual mags, that have 

little to do with maintenance or cost. Parts are available within normal 

aircraft pricing. Slick mags may be cheaper than Bendix to purchase, but 

they will cost you more in the long run, because after the first 

overhaul, they are not economical to do subsequent overhauls. Reliable? 

compared to what? Certainly not more reliable than the comparable Bendix 

models. A vast majority of mechanics will choose Bendix over Slick any 

day. Need less maintenance, need less parts replaced, and deliver a 

hotter spark.

Before TCM Bendix dropped its support for the dual mag, Lycoming charged 

typically $2500 to supply an engine with two single mags when the core 

engine had a dual mag. To make the changes needed, he is probably 

looking at similar or greater costs. Especially with shipping down 

under. Meanwhile, it is likely that by the time his mag needs an 

overhaul, there will be one or two electronic replacements available.

Kelly

A&P/IA



On 5/16/2017 4:24 AM, Peter Mather wrote:

 	  Quote: 	
		   John

 

 Iâ€™m flying a TB10 while building. This has a O-360 with the Bendix dual 

 mag. These things are a disaster for maintenance â€“ hugely expensive and 

 parts difficult/impossible to buy

 

 Depending on the state of your build I would seriously look at changing 

 the accessory housing and converting to a normal pair of Slicks. Better 

 redundancy, cheap and easy to maintain and solid reliability.

 

 Rgds

 

 Peter

 

 *From:*owner-aeroelectric-list-server(at)matronics.com 

 [mailto:owner-aeroelectric-list-server(at)matronics.com] *On Behalf Of 

 *John Keen

 *Sent:* 14 May 2017 08:19

 *To:* aeroelectric-list(at)matronics.com

 *Subject:* P-leads

 

 Hi Bob,

 

 I have an engine with the Bendix dual magneto. It came without P-leads, 

 so Iâ€™m wondering whether they are something I can fabricate or if I will 

 need to purchase them complete?

 

 Best regards,

 

 John.

 

 *John Keen*

 

 0412 141 833

 

 15 Scott St

 

 Scone NSW Australia 2337

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

pmather

Joined: 17 Sep 2009
Posts: 33

Posted: Tue May 16, 2017 1:31 pm Post subject: P-leads

" If it was such a bad device, why in the heck were you flying behind something depending on it?"



Try reading my post. I said it was "a disaster for maintenance" not that there was anything wrong with it as a functional unit or that it was unreliable.



"Before TCM Bendix dropped its support for the dual mag"



Exactly!



I've owned 8 aircraft with all varieties of mag. The last 500 hr overhaul on a pair of Slicks cost me Â£240 total (UK price). My dual mag needs a 6yr overhaul this year and will cost me cÂ£2000. 

By all means go for a pair of Bendix if you prefer them over Slicks but I stand by my advice to avoid the dual mags if long term budget is important to you



--

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Tue May 16, 2017 4:20 pm Post subject: P-leads

Just because TCM dropped support for the mag does not mean it doesn't 

exist. It also does not mean that in the USA cost is significantly 

different than maintaining two separate mags. Disaster for maintenance 

implies unexpected failures in my book. Examples done by quality mag 

shops in the US are not prone to failure before 500 hours, and are not 

out of sight on overhaul cost. Some engines they are used on, such as 

the O-320-H2AD, there is no single mag model made, you cannot convert.

Seems you could do an exchange with a US magneto shop for a lot less 

than what you are quoting. I'm not a fan of the dual head magneto, but 

it isn't nearly as bad as you portray.

Your Slick overhaul, if the price is for both, you can't achieve that in 

the US, and overhaul at 1000 hours will exceed the cost of new. In most 

any turbo-charged application the Slicks won't make 500 hours. In the US 

overhauling a Slick will cost as much or more than overhauling a Bendix.



On 5/16/2017 2:30 PM, Peter Mather wrote:

[quote] 

 

 " If it was such a bad device, why in the heck were you flying behind something depending on it?"

 

 Try reading my post. I said it was "a disaster for maintenance" not that there was anything wrong with it as a functional unit or that it was unreliable.

 

 "Before TCM Bendix dropped its support for the dual mag

 

 Exactly!

 

 I've owned 8 aircraft with all varieties of mag. The last 500 hr overhaul on a pair of Slicks cost me Â£240 total (UK price). My dual mag needs a 6yr overhaul this year and will cost me cÂ£2000.

 

 

 By all means go for a pair of Bendix if you prefer them over Slicks but I stand by my advice to avoid the dual mags if long term budget is important to you

 

 --

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

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