Precautionary/Emergency Landing due to Pmag Timing Failure

[nucleus]

Flying VFR on top today over Pennsylvania my engine started to run hot, and then rough. I saw a hole in the clouds and did sort of a spiral dive to get underneath the clouds and landed at Deck airport (9D4) in Lebanon PA. I did not remember to try switching ignitions until I was taxiing, huge backfires and sputtering with the Right ignition selected. The kind and helpful people at Shearer Aviation loaned me some tools and hanger space, I did compression tests and checked the timing. Sure enough the Right Pmag was way off. I Fedexed both Pmags off to Brad for a quick repair/check/update. I had not send them in for the recall because they were made and serviced before the dates in the bulletin. Maybe this was a mistake. I will update this thread when I know more.

Hans

My passenger had a post on facebook about this within 20 minutes of landing. Seems wrong!

[Ron Lee]

Just a note to others. I am assuming that regardless of your ignition system, you may need to check between the two units inflight if a possible ignition problem develops.

Personally, I would rather run on one good ignition system and get on the ground quickly than have symptoms such as you describe adding to the stress.

Keep up to date on maintaining those ignition systems.

[Kevin Horton]

It is a good idea for every RV pilot, even those with two mags, to spend some time creating a "Rough Running Engine" checklist. The time to think about this scenario is on the ground, when you can devote 100% of your brain power to the problem. Come up with a logical set of actions to do if you ever have a rough running engine. Write them down in a check list, and pull it out and use it if you ever have a rough running engine in flight.

[KirkGrovesRV8]

Dr Hans if you need anything let me know I am just southof you a little ways at Smoketown, please call if you need anything at all.
Kirk 610-283-2448

[nucleus]

Originally Posted by Kevin Horton

It is a good idea for every RV pilot, even those with two mags, to spend some time creating a "Rough Running Engine" checklist. The time to think about this scenario is on the ground, when you can devote 100% of your brain power to the problem. Come up with a logical set of actions to do if you ever have a rough running engine. Write them down in a check list, and pull it out and use it if you ever have a rough running engine in flight.

It was on my mental checklist but not written down. The mental checklist failed in flight.

Hans

[RV7Guy]

This was discussed in another thread. It is critical to have 100% knowledge, 100% of the time for Emergency Procedures.

Here is mine for my Pmag equipped IO360. This will be for rough running, CHT rise.

1) Reduce throttle and turn on auto pilot if you have one. This will slow the advance of the timing and lower the temps.

2) Richen the mixture with a quick twist.

3) Do a mag check with the L/R/Both switch. (whatever type you have) Leave the switch on which ever mag runs smoothly.

4) Monitor the temps for trends use mixture to assist in keeping temps good.

5) Once stabilized and if comfortable doing so, do another mag check and confirm the problem.

6) Depending on where you are, fly on or choose a nearby airport.


Practice this process. Know where everything is, the settings and airspeeds. For me, I reduce the power to fly at 90 kts with a few degrees of flaps. This provides a low power setting but enough airspeed to maneuver safely and keep the temperatures down.

[John Clark]

Originally Posted by nucleus

It was on my mental checklist but not written down. The mental checklist failed in flight. Hans

Sadly, mental checklists almost always fail in flight. Stress seems to make them evaporate. The accepted procedure is to come up with a couple of "memory items", the things that you need to do now, in your case, something like "Reduce power" and "Establish glide" then get out the checklist and do some troubleshooting.

John Clark
RV8 N18U "Sunshine"
KSBA

[frankh]

I don't know of any E/P mags that have failed after the latest updates.

Frank

[David-aviator]

Originally Posted by frankh

I don't know of any E/P mags that have failed after the latest updates.

Frank

I do not have e-mag or p-mag but just read the service bulletin that came out last year on the attachment of the timing sensor to the shaft.

Unless the sensor has the roll pin attach modification, it seems like it would be a good idea to not fly the airplane until this is complied with. The method developed in 2007 is not bullet proof and is the reason for the change last year.

I like the system, based on reading about it, but loss of timing in flight is not acceptable. If nothing else there ought to be a circuit that terminates the unit operation if its timing input exceeds a pre set envelop.

[Ron Lee]

I am not current on PMag issues either but at one time I would have recommended NOT using the blow tube method to set timing. Unconfirmed opinion is that it had a potential to fail so using the "mechanical" method seemed to be what I would have used.

Obviously don't use these comments for anything other than to make sure you have recommended improvements implemented.

A few years ago, I was hesitant to switch between mag settings airborne, but finally did it. This is the second incident that I have heard of with PMags that checking the Left/Right switch may have helped.