ever had your timing "slip"?

[peevee]

Just curious if this even happens to folks, I've never heard of it.

We had the mags overhauled and when the A&P put them back in, he had some trouble getting them timed. It flew OK for a few flights then we saw more drop and differential than we should, so he re-timed them and said it "slipped". As I said it's not something I've heard of in my limited experience. They're bendix mags.

[OR75]

the mag probably slipped while he was torque-ing the bolts 

the bolts should be torqued very gradually and checking the timing is not slipping while torque-ing 

[MB65E]

I have had new mags advance during short brake in periods. After that initial say 10hrs and mag re-test, they are usually solid. 

I still use a torque wrench on mine, and after they are fully torqued I'll run another test with the box. 

"Silpped" I'd say is a lazy word for didn't get it right the first time. they may have slipped if the old locking hardware was used. 

-Matt

[Shadrach]

My mags have never "slipped"... I check my timing at annual and it remains dead on and well sync'd. I get 0 drop from left to right. I have had my aircraft returned to me with the mags timed into the next time zone. Nothing like firing up the engine for a post $5500 annual flight and getting a 500RPM mag drop.

[Guest]

Poor installation technique is another word for slipped.  New gaskets, new hardware, new lock washers along with a current copy of TCMs sb 94-8D and a calibrated torque wrench keep things from slipping.

Clarence

[peevee]

Thanks guys 

[clh]

I had one slick mag that drifted pretty much the entire time I had it.  Several different A&Ps worked on it none could figure it out.

Used the mag drop to remind me of time for oil change. Oil change checklist incluced re-timing the left mag.  Finally chucked the slicks in the dumpster...  no problems since.

 

[Mcstealth]

25 minutes ago, clh said:

I had one slick mag that drifted pretty much the entire time I had it.  Several different A&Ps worked on it none could figure it out.

Used the mag drop to remind me of time for oil change. Oil change checklist incluced re-timing the left mag.  Finally chucked the slicks in the dumpster...  no problems since.

 

I thought the consensus was that Slick Mags were a good upgrade?

[jetdriven]

6 minutes ago, Mcstealth said:

I thought the consensus was that Slick Mags were a good upgrade?

Umm, nobody thinks that. 7,8 years ago maybe 

[clh]

51 minutes ago, Mcstealth said:

I thought the consensus was that Slick Mags were a good upgrade?

yep, upgraded to slicks ~500 hrs ago and then upgraded back to bendix....... only in aviation.

[Andy95W]

1 hour ago, jetdriven said:

Umm, nobody thinks that. 7,8 years ago maybe 

My experience also.

[helitim]

The only real advantage I can think of with dual slicks (or Bendix for that matter) would be that you could then add a slick start to the system for easier starting.  We added slick start to our Archer and 152,  it made a significant difference in ease of start.

Tim

[jclemens]

If you are referring to Slick mags, don't be so quick to blame the technician that installed them.  Saying the timing "slipped" could have just been his way of saying the timing is not what it was when he set it a few hours before.  Theres a well known (but completely ignored by Champion) issue with new Slick points.  They all seem to be incapable of staying timed in the first few hours.  We change points in Slicks every 500 hours, most of those mags come back off before the next oil change to have the points retimed.  We are a 145 repair station with a full engine overhaul facility including magneto capability.  We know what we are doing and have all the fancy test equipment to back it up.  It is by no fault of ours, something in the way the point sets are being made has changed, and not in a good way.  Voicing concern to a Champion rep netted us a bunch of free T-shirts and a bag of mag timing cams.  If your technician simply retimed the mags to the engine and did not retime the internal timing of the mag it is very likely that your lag angle is incorrect and will cause the engine to be hard to start, amongst other things.  If he/she is uncomfortable inside a mag PM me and I will arrange to have them sent to my facility and I will personally go over them free of charge.

[carusoam]

JC,

Thank you for sharing the detailed insight.

Any idea if the mags are holding the timing after the few hours of break-in that you described?

Best regards,

-a-

[peevee]

18 minutes ago, jclemens said:

If you are referring to Slick mags, don't be so quick to blame the technician that installed them.  Saying the timing "slipped" could have just been his way of saying the timing is not what it was when he set it a few hours before.  Theres a well known (but completely ignored by Champion) issue with new Slick points.  They all seem to be incapable of staying timed in the first few hours.  We change points in Slicks every 500 hours, most of those mags come back off before the next oil change to have the points retimed.  We are a 145 repair station with a full engine overhaul facility including magneto capability.  We know what we are doing and have all the fancy test equipment to back it up.  It is by no fault of ours, something in the way the point sets are being made has changed, and not in a good way.  Voicing concern to a Champion rep netted us a bunch of free T-shirts and a bag of mag timing cams.  If your technician simply retimed the mags to the engine and did not retime the internal timing of the mag it is very likely that your lag angle is incorrect and will cause the engine to be hard to start, amongst other things.  If he/she is uncomfortable inside a mag PM me and I will arrange to have them sent to my facility and I will personally go over them free of charge.

Appreciate it, they're Bendix though. Gonna go fly the plane today, he says they're spot on now. 

[aviatoreb]

On November 30, 2015 at 5:02:31 PM, peevee said:

Just curious if this even happens to folks, I've never heard of it.

You too?  My timing slips all the time.

Oh wait - you meant my airplane?  Never mind.

[Bartman]

I had an oil leak right after I bought my 77J and annual by an unknown mechanic.  The mag did "slip" but that's because the dual mag was loose !!!

[cliffy]

Dual mag loose? Probably due to not replacing lock washers and improper torque on hold down nuts.

I flew duals on a twin for thousands of hours and never had a problem with them when we did the work correctly. 

[philiplane]

timing that changes more than a few degrees, like 2-3 max, in less than 250 hours means something is wrong with the points. And, If a magneto is loose enough for the mag to engine timing to change, it will leak oil like crazy. So you have to investigate the "slippage". Was it simply set wrong in the first place, or is the internal mag timing changing? The former is an installation error but the latter is a potential problem that requires mag disassembly to verify the point setting.