VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 01-05-2012, 04:12 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 9,328
Default P-Mag Operating Temperatures

P-mags contain an internal temperature sensor. Temperature output is available via laptop or EI Commander. Has anyone actually measured the internal temperature of their P-mags with and without blast tubes?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #2  
Old 01-06-2012, 01:39 PM
lostpilot28's Avatar
lostpilot28 lostpilot28 is offline
 
Join Date: Nov 2006
Location: Boise, ID
Posts: 1,095
Default

You know that Bill Repucci is the best guy to answer this...or anyone that uses his EI Commander. I'll be interested to see what the responses will be.

BTW, Dan, the whole reason I started that thread about measuring cowl pressure differential was because of a conversation that I had with Brad at eMag. I was perfectly content with my "slightly high" temps until he told me that I could experience thermal shutdown if they get much above 210 (F).

This conversation took place because I sent my Pmag in for repair and he said that the thermal sticker on the outside was tripped. I want to say that it was a 200 degree sticker, but maybe it was only 190.
__________________
Sonny W
Boise, Idaho
RV-7A Flying!
Reply With Quote
  #3  
Old 01-06-2012, 01:48 PM
RV8R999 RV8R999 is offline
 
Join Date: Dec 2008
Location: na
Posts: 1,457
Default

Sonny - good info and thanks. I have one P-mag and one slick. I'd be willing to block off the blast-tube to the slick, never had one in other planes I've owned, but probably leave the P-mag alone.
Reply With Quote
  #4  
Old 01-06-2012, 02:31 PM
John Collier John Collier is offline
 
Join Date: Apr 2005
Location: Niceville, FL
Posts: 81
Default Maybe a stupid question...but

wouldn't the temp rise above 200 upon shutdown if you are operating in a high OAT enviroment? I think I've had a conversation with Bill about this...as the EIC only records the max temp...not the current operating temp? Am I missing something?

v/r
John
__________________
John Collier
RV8
N774BC
Niceville, FL
Reply With Quote
  #5  
Old 01-06-2012, 02:42 PM
lostpilot28's Avatar
lostpilot28 lostpilot28 is offline
 
Join Date: Nov 2006
Location: Boise, ID
Posts: 1,095
Default

Brad was fairly vague about the "thermal shutdown" of a Pmag, but he did say it's a risk. I said it was over 210, but I think Brad actually said "around 220" is when the risk becomes real. Either way, my impression is that he is being very conservative and for good reason.

I really don't know when or if a Pmag would shutdown from getting too hot. I would hope one never does, but I wouldn't pin my life on it. He said to put blast tubes on it, and my guess is that they don't want to see them get much over 200...so that's what I'm doing.
__________________
Sonny W
Boise, Idaho
RV-7A Flying!
Reply With Quote
  #6  
Old 01-06-2012, 02:46 PM
N941WR's Avatar
N941WR N941WR is offline
 
Join Date: Jan 2005
Location: SC
Posts: 12,887
Default

Quote:
Originally Posted by John Collier View Post
wouldn't the temp rise above 200 upon shutdown if you are operating in a high OAT enviroment? I think I've had a conversation with Bill about this...as the EIC only records the max temp...not the current operating temp? Am I missing something?

v/r
John
Dan and I spoke earlier in the week but I didn't have an answer for him. I hope to get out this weekend and block one of the blast tubes and watch what happens. (If the temp goes too high, I can shut off the one ignition and get home on one P-mag.)

The P-mag records the max temp, not the EICommander. However, the EICommander will display the current temp.

You are correct, on a hot day, if you land, shut down and do a quick turn, the P-mag will be heat soaked and will record the high temp it sees when you power them back up. Unfortunately, there is no way for the EICommander to clear the high temp recorded in the P-mag, that has to be done at the factory.

(We have asked for the ability to clear this temp and have been turned down. We did talk about recording the max temp in the EICommander but discounted it because it would only record the max temp on a hot / quick turn, same as the P-mag.)
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
Reply With Quote
  #7  
Old 01-06-2012, 04:16 PM
RV7ator RV7ator is offline
 
Join Date: Jan 2005
Location: Boise, ID
Posts: 1,007
Default Perhaps a Latent Problem Remains

Given there are now many more fleet hours on P-mags than when the SB3 was released (three years ago), problems just don't seem to be going away, though VAF has been fairly quiet.

I have personal knowledge of two other ships that this week had their ignitions back to E-mag for failure issues, and both had SB3 incorporated.

One requires some adjustment to shaft end play (a point mentioned in SB2). So why is this now apparent and wasn't back at zero time?

The second failed in the classic lost timing mode wherein all h*ll breaks lose on power up for take off. (I've been experienced this twice myself.) Here's the owner's report to me. "Brad initially denied that there was a problem with Pmag but today he told me he had an ?anomaly? when he first checked it but couldn?t replicate. He replaced the main circuit board (said it had discoloration from heat in one spot) and replaced the coil. $450 later it is being shipped back today."

I know another local pilot who crash a few seconds after take-off. Supposedly the cause was fuel starvation, but another pilot familiar with the sound of ignition failure is convinced a failed ignition is the culprit. This remains conjecture since the owner has yet to have E-mag check his ignitions. I remain highly suspicious.

My concern is that P-mag electronics are proving razor-thin close to getting cooked in their natural, normal operating environment. Brad once told me they conform to the same temperature spec as magnetos, but the only thing electronic on a mag is the capacitor, and it's loss only hastens point erosion, not instant failure.

So let's have a show of hands: who has had, or has first-hand knowledge of, P-mag problems in the last three years? Electrical or mechanical difficulties? Was SB3 incorporated? Blast tube or no?

I'm real interested in Bill R's report.

I know P-mags have shut down protocols if something's out of whack at start-up. But to shut down an operating ignition to save itself seems as looney as sawing off the limb between you and the trunk. And if it shuts down because it can't hack it's natural environment, that's a design problem.

John Siebold
Reply With Quote
  #8  
Old 01-06-2012, 04:17 PM
Brantel's Avatar
Brantel Brantel is offline
 
Join Date: Mar 2006
Location: Newport, TN
Posts: 7,487
Default

Keep on mind that the guys from Emag have stated that the internal temp sensor is not calibrated and may not be accurate.
__________________
Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Working on Wings
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook
Reply With Quote
  #9  
Old 01-06-2012, 04:23 PM
RV7ator RV7ator is offline
 
Join Date: Jan 2005
Location: Boise, ID
Posts: 1,007
Default This Just In...

One of the pilots in my above post has a further tidbit from Brad.

The on-board temperature recorder is unreliable. There's enough RF about to sometimes set it off, recording an impossibly high number. E-mag therefore is not relying on it as gospel.

Of course, the external dot only monitors its immediate locale, a poor indicator of what's happened internally.

John Siebold
Reply With Quote
  #10  
Old 01-06-2012, 07:03 PM
CDN CDN is offline
 
Join Date: Nov 2011
Location: Calgary, AB
Posts: 125
Default Discrete component temperature range

The type of capacitors that you find in most magnetos have a maximum operating range of 85 or 105?C (185 or 221?F), depending on the manufacturer. I hope that they use the ones with the higher rating but don't know for certain. Regular industrial grade silicon based, PN-junction components (transistors, ICs, etc) normally have a maximum operating temperature of 85?C while mil spec versions of the same components have a max operating temperature of 125?C (257?F). Again, I hope E-mag uses the better versions in their products but don't know that to be fact. Heat is the enemy of any electrical circuit. Magneto manufacturers recommend blast tubes for the same reason that E-Mag does. Cooler operation is better for the life of magnetos, E-Mag products, or any other electrical/electronic device.

My friend had chronic CHT and oil temp issues in an RV4 (severe cam problem related to poor machine work for fancy new camshaft) and never had any noticeable heat soaking problems with his P-Mags in Gulf Coast summer heat. He did have blast tubes and they were the 113 versions, before the extra cooling fins machined into the case. He's a member on here so I welcome him to chime in with his first hand experience.

I personally cannot speak to operation in high ambient temperatures because the Alaska climate is well suited for operation of such accessories. My maximum temperature is recorded as 184?F and that was probably recorded during the first couple of flights before the blast tube was installed.

However, my P-Mag did have a mechanical failure at about the 220 hour mark due to the failure of a small component (finger spring washer IIRC) on the shaft causing misalignment of the shaft position sensor. The washer most likely failed in flight but the ignition kept on ticking until I tried a restart after refueling. During initial troubleshooting I discovered a blinking amber LED on the P-Mag indicating shaft misalignment. Rotating the prop and recycling the power (tried this sequence about 5 times before it was successful) allowed me to restart the engine. Doing this outside at an OAT of -10 sucked though. It was well beyond the warranty period but Brad at EMag fixed it for the cost of shipping, $15. If I got that kind of service when my Slick magneto experienced a problem at less than 100 hours (albeit 4 years after initial purchase) I may still be using it. That's when I decided to upgrade to the P-Mag EI as a replacement in the first place, and I'm still happy I did.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 12:18 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.