Inflight Mag Check

[rsuncloud]

I have been reading about testing the ignition system under stress.
Has anyone performed an inflight mag check?
What procedure did you use?
Who would be afraid to try without a flight instructor or fighter jock at their side?

[Al Sayre]

Bad idea.  Leave the nonstandard procedures to the mechanic

[TheSkyHornet]

Absolutely an appropriate thing to do when flying.

If the engine is running rough on both magnetos, follow your normal procedures (carb heat, if applicable, fuel, etc.). No harm in switching the key over to the right mag, then left mag, to determine if there's a magneto shorting. If you're running off of a rough magneto and a good magneto on "both," you may be drawing power away from the engine. If it's a magneto problem, you're going to want to identify it and plan to get on the ground as soon as possible.

[Panzerbjorn]

Why on earth would you test your magnetos in flight?  That's what a run-up is for.  What if you did lose a magneto in flight?  Now, by you 'testing' it, you've just potentially shut off your engine.  In my mind, testing your magnetos in flight to see if you have a magneto problem ranks right up there with turning your fuel selector valve to 'OFF' to see if you're experiencing a fuel line blockage problem.

If the engine is running rough, and you suspect a magneto, just get it on the ground.  Your engine is running, even if it's rough, so leave it running.  Don't do something that could turn a problem into an emergency just so you can try and diagnose a problem.  Get it on the ground if you suspect a real problem, THEN mess around with the mags or whatever else you think might be the problem.

[Live2Learn]

Why on earth would you test your magnetos in flight?  That's what a run-up is for.  What if you did lose a magneto in flight?  Now, by you 'testing' it, you've just potentially shut off your engine.  In my mind, testing your magnetos in flight to see if you have a magneto problem ranks right up there with turning your fuel selector valve to 'OFF' to see if you're experiencing a fuel line blockage problem.

If the engine is running rough, and you suspect a magneto, just get it on the ground.  Your engine is running, even if it's rough, so leave it running.  Don't do something that could turn a problem into an emergency just so you can try and diagnose a problem.  Get it on the ground if you suspect a real problem, THEN mess around with the mags or whatever else you think might be the problem.

Sometimes "just getting on the ground" isn't a really immediate option.  For example, while crossing an extended area of really rough terrain, or when over water at the margin of glide (we don't fly SEL over wide bodies beyond glide from land w/o proper gear, right?).   A mag check to isolate the bad mag is good trouble shooting.  As a 'normal' practice, I don't think a mag check in the air is a good idea since one click past the second mag is one click too many.  In flight mag checks are definitely an abnormal procedure done for a specific purpose.  I don't think an inflight mag failure is specifically addressed in the POH for the aircraft I've flown.  It really is surprising how much power we lose in our piston engine aircraft when one of our mags fails.

[TheSkyHornet]

Why on earth would you test your magnetos in flight?  That's what a run-up is for.  What if you did lose a magneto in flight?  Now, by you 'testing' it, you've just potentially shut off your engine.  In my mind, testing your magnetos in flight to see if you have a magneto problem ranks right up there with turning your fuel selector valve to 'OFF' to see if you're experiencing a fuel line blockage problem.

If the engine is running rough, and you suspect a magneto, just get it on the ground.  Your engine is running, even if it's rough, so leave it running.  Don't do something that could turn a problem into an emergency just so you can try and diagnose a problem.  Get it on the ground if you suspect a real problem, THEN mess around with the mags or whatever else you think might be the problem.

Sometimes "just getting on the ground" isn't a really immediate option.  For example, while crossing an extended area of really rough terrain, or when over water at the margin of glide (we don't fly SEL over wide bodies beyond glide from land w/o proper gear, right?).   A mag check to isolate the bad mag is good trouble shooting.  As a 'normal' practice, I don't think a mag check in the air is a good idea since one click past the second mag is one click too many.  In flight mag checks are definitely an abnormal procedure done for a specific purpose. I don't think an inflight mag failure is specifically addressed in the POH for the aircraft I've flown.  It really is surprising how much power we lose in our piston engine aircraft when one of our mags fails.

This.

A mag check in the air should only be performed as a method of trouble-shooting. It is not a normal procedure. It would be an abnormal procedure, not an emergency procedure. So, this is not something you would do when your engine quits, but if you did a run-up on the ground, leaned the mixture, used carb heat (if applicable), and you're still getting a rough-running engine, check the mags, WHILE making your way to a nearby airport.

This is something I was taught when I was doing my flight training. I actually had this discussion with a coworker after reading this, who is a CFI and A&P. He, too, said it's totally fine, if not a "good idea" to do in a case such as this.

[Cliff_Chambliss]

I did that exactly one time - never again.   I was asked (tasked?) by the FBO owner to go pick up one of the rental aircraft that had been left (abandoned?) by a renter pilot approximately 100nm away.  The renter pilot said that after his last refueling stop and about 30 minutes into the flight the engine started running  real rough and shaking so he landed at the first airport he saw (a very smart move).  The next morning the owner contacted the FBO at the airfield and asked for a check of the aircraft.  A short while later they called and said except for a bit of water in the fuel they could find nothing wrong, and on runup both mags checked good, so off we went on a recovery mission.
  I did a really in depth preflight and runup and tested the throttle through its full range.  everything sounded good and felt good so we launched planning to fly formation back to homedrome.  About 15 minutes into the flight the engine started acting like it wanted to jump out of the airplane.  missing, backfires, lots of vibration.   Trying different power settings and mixture setting would result in brief improvement but only for moments.
  It was then I decided to "Test the mags"  One click right, no change.  AH HA, thought I, no change so it's the bad mag, lets go two clicks right and then total silence.  I mean that engine stopped stone cold dead.  now 2500 feet over the hills and forests of North Carolina is no place for a Cessna C-172 pretending to be a glider.  Back one click left - no change, back to both and I got some power back and I left everything alone until we got back.
aftermath:  A full inspection of the engine later revealed a "perfect storm" of several issues:   The failed mag was not approved for the aircraft.  Someone made a mistake and installed the wrong part.  However, the mag was perfect.
Other mag way out of time and way past overhaul.
Ignition switch:  This was the real demon:  Highly worn and suffered a heat breakdown which completely shutdown the good mag and would not always make contact when switching between mags.   Lesson learned:  Sometimes a mag issue may not be a mag issue at all and may be an ignition switch issue.  I was lucky that day because playing test pilot could have turned ugly.

[TheSkyHornet]

At the end of the day, you're responsible for the safety of the flight.

Make a decision. If it seemed like a reasonable choice and worked out well, good. If it seemed like a reasonable choice and didn't go so well, suck, doesn't it? If it was a terrible choice and you knew better, own up to it and be prepared for the consequences.

There's no "perfect" way to troubleshoot when you don't know what the problem is, especially if you haven't experienced it before. If you knew what the issue was before takeoff, you wouldn't have taken off.

[Live2Learn]

At the end of the day, you're responsible for the safety of the flight.

Make a decision. If it seemed like a reasonable choice and worked out well, good. If it seemed like a reasonable choice and didn't go so well, suck, doesn't it? If it was a terrible choice and you knew better, own up to it and be prepared for the consequences.

There's no "perfect" way to troubleshoot when you don't know what the problem is, especially if you haven't experienced it before. If you knew what the issue was before takeoff, you wouldn't have taken off.

Bingo.  But, let it be an 'informed' decision if at all possible.  If it doesn't help... return to the previous settings! 

IMHO, abnormal procedures are just that.  They're to address the unusual event that may (or may NOT) rise to an emergency -- and therefore ain't likely to be covered in the emergency checklists and procedures.

The first 'abnormal procedure' begins with:  If I don't know why the plane isn't behaving and previous bad behavior hasn't been thoroughly trouble shot... don't launch.

[Panzerbjorn]

Sometimes "just getting on the ground" isn't a really immediate option.  For example, while crossing an extended area of really rough terrain, or when over water at the margin of glide (we don't fly SEL over wide bodies beyond glide from land w/o proper gear, right?).  A mag check to isolate the bad mag is good trouble shooting.  As a 'normal' practice, I don't think a mag check in the air is a good idea since one click past the second mag is one click too many.  In flight mag checks are definitely an abnormal procedure done for a specific purpose.  I don't think an inflight mag failure is specifically addressed in the POH for the aircraft I've flown.  It really is surprising how much power we lose in our piston engine aircraft when one of our mags fails.

Okay, so in that kind of scenario, your instinct tells you that you should do something that could potentially shut your engine off?  That really is something that can lead to..."Wow, I was right!  It was the mag!" in the deafening silence as your engine quits just like how Cliff narrated in his story (Thank you, Cliff, for illustrating my point.)

I definitely agree that it should not be a 'normal' procedure under any circumstance.  But I have to admit that I can't think of a single scenario where it would make it a good idea in my mind to turn that key and see if my hunch that I've lost a mag actually happened.  What I WILL concede, however, is that with a windmilling prop, turning the key over to BOTH or the good mag should at least get the engine going again almost immediately.  But if I saw the pilot reach over and just decide to do an in-flight mag check with me in the right seat, there would be colorful metaphors aplenty.

[JeffDG]

On a risk-v-benefit basis:  What does determining that the problem is indeed a bad mag give you in flight?

OK, so you have a dead mag?  That's why you have 2.  You're going to be underpowered, but you already knew that before testing.  So, it really gives you no discernible benefit.

On the risk side, you have the scenario described above where it just might not come back, and then you've lost 100% of your power.

Risk of serious escalation of the problem vs. no discernible benefit...fairly easy call IMHO.

[Cliff_Chambliss]

Please let me add a couple items to my earlier posting.
* Before I even left our home field the maintainer at the off site location had examined the aircraft, checked the fuel and found some water which he drained out.  He an up the engine and checked the mags at various settings and said they sounded good.
* Before I took off in the "wounded" airplane I performed a through preflight including runup and mag check at various power settings and everything checked OK.
*  As soon as the engine began to misbehave we (me and the escort) diverted to the nearest airfield which was the one we left from.

My only mistake was in trying to play "test pilot" over very unfriendly terrain and not having a well thought out plan of action.

Defense:  I was still somewhat young, dumb, and invincible stationed at Ft Bragg, NC, and recently returned from Vietnam.

this was another item removed from the bag of luck and put into the bag of experience.

[JeffDG]

this was another item removed from the bag of luck and put into the bag of experience.

And, thanks to you sharing your experience, other pilots can add it to their bag of experience at no cost to their own personal luck bag!

[C/SrA Ravlin]

If you are experiencing a rough engine then the first thing you should do is turn on the carb heat... This will make the engine run rougher for a few minutes wether or not carb ice is present... If it is the engine will run extremely rough until the ice melts. The next thing would be to switch fuel tanks... Gas gauges are not the most reliable gauge in the cockpit. After that check your mixture. Try different mixtures and see if the engine runs better at a certain setting. After that try the magnetos... If one runs better or there is more than a 50-90rpm drop between the 2, then use the one with higher rpms and call for a priority landing if with atc or tell someone if you are on Unicom. Hope this helps.

[Panzerbjorn]

If you are experiencing a rough engine then the first thing you should do is turn on the carb heat... This will make the engine run rougher for a few minutes wether or not carb ice is present... If it is the engine will run extremely rough until the ice melts. The next thing would be to switch fuel tanks... Gas gauges are not the most reliable gauge in the cockpit. After that check your mixture. Try different mixtures and see if the engine runs better at a certain setting. After that try the magnetos... If one runs better or there is more than a 50-90rpm drop between the 2, then use the one with higher rpms and call for a priority landing if with atc or tell someone if you are on Unicom. Hope this helps.

The first suggestion is not really an option in fuel injected engines.

Adding carb heat does not "make the engine run rougher". You just simply have a slight loss of power and about a 50 RPM loss.  It's the carb ice that makes your engine run roughly, not the carb heat.

Cessnas normally operate drinking from both tanks at once.  You're only supposed to run on one if necessary and only in straight and level flight.  So switching the tank wouldn't really have all that big of an effect in a Cessna unless you have a fuel line blockage or water in your fuel.

Operating on a single mag and the engine is not showing signs of quitting on you is really more of a land as soon as practical situation than it is an emergency one and asking ATC for priority handling.  If you do that, you're more likely to be landing with a fire engine escort dispatched as a 'just in case' measure.  Also, more often than not, the difference in RPM drop has to do with somewhat fouled plugs, which can be remedied by leaning out the mixture, raising the CHT, causing the lead deposits to melt and clear the plug.  As far as your suggestion to "use the one with higher rpms...."  Please show me where that procedure is printed in ANY POH saying you should switch off a magneto in flight in accordance with your suggestion.

[Flying Pig]

If you are experiencing a rough engine then the first thing you should do is turn on the carb heat... This will make the engine run rougher for a few minutes wether or not carb ice is present... If it is the engine will run extremely rough until the ice melts. The next thing would be to switch fuel tanks... Gas gauges are not the most reliable gauge in the cockpit. After that check your mixture. Try different mixtures and see if the engine runs better at a certain setting. After that try the magnetos... If one runs better or there is more than a 50-90rpm drop between the 2, then use the one with higher rpms and call for a priority landing if with atc or tell someone if you are on Unicom. Hope this helps.

Switch to one mag and run it at higher RPMs? What airplane are you flying that has this listed as a procedure?

[PHall]

If you are experiencing a rough engine then the first thing you should do is turn on the carb heat... This will make the engine run rougher for a few minutes wether or not carb ice is present... If it is the engine will run extremely rough until the ice melts. The next thing would be to switch fuel tanks... Gas gauges are not the most reliable gauge in the cockpit. After that check your mixture. Try different mixtures and see if the engine runs better at a certain setting. After that try the magnetos... If one runs better or there is more than a 50-90rpm drop between the 2, then use the one with higher rpms and call for a priority landing if with atc or tell someone if you are on Unicom. Hope this helps.

Switch to one mag and run it at higher RPMs? What airplane are you flying that has this listed as a procedure?

Microsoft Flight Simulator.

[Panzerbjorn]

If you are experiencing a rough engine then the first thing you should do is turn on the carb heat... This will make the engine run rougher for a few minutes wether or not carb ice is present... If it is the engine will run extremely rough until the ice melts. The next thing would be to switch fuel tanks... Gas gauges are not the most reliable gauge in the cockpit. After that check your mixture. Try different mixtures and see if the engine runs better at a certain setting. After that try the magnetos... If one runs better or there is more than a 50-90rpm drop between the 2, then use the one with higher rpms and call for a priority landing if with atc or tell someone if you are on Unicom. Hope this helps.

Switch to one mag and run it at higher RPMs? What airplane are you flying that has this listed as a procedure?

Microsoft Flight Simulator.

Considering some of the habits I saw some cadets come home with this summer, I can't help but speculate if he learned this at a Powered Flight Academy,

[PHall]

If you are experiencing a rough engine then the first thing you should do is turn on the carb heat... This will make the engine run rougher for a few minutes wether or not carb ice is present... If it is the engine will run extremely rough until the ice melts. The next thing would be to switch fuel tanks... Gas gauges are not the most reliable gauge in the cockpit. After that check your mixture. Try different mixtures and see if the engine runs better at a certain setting. After that try the magnetos... If one runs better or there is more than a 50-90rpm drop between the 2, then use the one with higher rpms and call for a priority landing if with atc or tell someone if you are on Unicom. Hope this helps.

Switch to one mag and run it at higher RPMs? What airplane are you flying that has this listed as a procedure?

Microsoft Flight Simulator.

Considering some of the habits I saw some cadets come home with this summer, I can't help but speculate if he learned this at a Powered Flight Academy,

So you're saying that your cadets were taught incorrectly by CFI's.  Interesting...

[Panzerbjorn]

If you are experiencing a rough engine then the first thing you should do is turn on the carb heat... This will make the engine run rougher for a few minutes wether or not carb ice is present... If it is the engine will run extremely rough until the ice melts. The next thing would be to switch fuel tanks... Gas gauges are not the most reliable gauge in the cockpit. After that check your mixture. Try different mixtures and see if the engine runs better at a certain setting. After that try the magnetos... If one runs better or there is more than a 50-90rpm drop between the 2, then use the one with higher rpms and call for a priority landing if with atc or tell someone if you are on Unicom. Hope this helps.

Switch to one mag and run it at higher RPMs? What airplane are you flying that has this listed as a procedure?

Microsoft Flight Simulator.

Considering some of the habits I saw some cadets come home with this summer, I can't help but speculate if he learned this at a Powered Flight Academy,

So you're saying that your cadets were taught incorrectly by CFI's.  Interesting...

When I had one who was taught that standard procedure to start the engine is to pump the throttle furiously as you crank it AND come home with the habit of making a 45 degree bank from base to final.....I MIGHT be suggesting that there are some issues with what's being taught, yes.  Not in all cases because I'm not going to generalize, but clearly there's at least one CFI there that could benefit from some remedial training.

[C/SrA Ravlin]

When I say to run the one with higher rpms you only do this in an emergency situation... One of the mags will run better than the other and if you having trouble with one then switch to the other... The other will often run with higher rpms than the one that is having issues. Again this is for emergencies only!!!! Doing this under normal circumstances can be dangerous... And someone please correct me if I am wrong because I am a learning student pilot and need to know the correct version if this is incorrect. Also this completely depends on the plane you are flying. As stated earlier with the fuel selector issue. If there is water in the fuel than the engine will either quit or run extremely rough until the water is gone. Again please correct me if I am wrong...

[Flying Pig]

What airplane are you referring to.  I have about 1800hrs in FW in 172s, 182s, 206s, 210s, Warriors, Tomahawks, Arrows.....  Ive never heard of or read any procedures to switch to "the good Mag" and run the RPMs higher.  Instead of asking us if you have it wrong, show us where you were taught or read that.  There could be a plane out there that has that.  I would sincerely like to know which one it is.  Maybe I missed it.  This sounds more like a procedure someone used once or something thats been handed down over the years and nobody knows who made it up.  If one Mag is bad, rough is rough.  Im not a mechanic, but Im not seeing how shutting the bad one down improves your situation.
Running at higher RPMs compared to what?  RPMs are RPMs.  So do you now land faster because you have a bad mag?  Just saying "run at higher RPMs" leaves a lot out of the scenario.  Is this a constant speed prop? Fixed Pitch?  Is there a corresponding air speed you are looking for? Do you ever go to "Both" again?  What about 1-Mag go around procedures?  All these things would need to be addressed if this is a written EP.  Also... I wouldnt necessarily treat a bad mag as an Emergency.  You said "You only do this in an emergency".  So is that an Emergency.... and then you lose a mag?  Or does losing the mag make it an emergency situation?  If it does, simply go to the EP section of your POH and tell us what it says.

[Flying Pig]

If you ever fly for CAP as a Mission Pilot (or fly anything)....... beware of the official looking home made checklist the pilot before you leaves in the airplane.  Sometimes they can be quite entertaining   

[Luis R. Ramos]

There are lots and lots of things in life that I have learned from books, or done but I would never ever think to offer advice as it was done here. I left the experts -those that have countless hours in cockpits in several airplanes- be the ones offering advice on what to do.

Can you imagine me offering advice to Flying Pig or to Shuman because once while employed as an orderly at a hospital accompanied a Security Guard in a safety sweep?

Can you imagine me offering advice to PHall, Jeff, or Cliff (among others!) on air warfare because I have read about 70 books in air warfare or airplanes plus 50 books on land warfare, plus about 20 on naval warfare?

If you were not a pilot you should have stated so. Although most guessed it by your signature, and the advice...

Even if you want to help, please do not do it until you can profer countless hours in real life...

[Panzerbjorn]

Here's the thing about aviation, no matter how much experience you have, no matter what ratings you hold, there's always room to learn things.

Here's an article from AOPA's Flight Training talking about this very thing and it supports Ravlin's advice, with a little more clarification as to why you would want to turn off a mag in flight.  Apparently, it has to do with the timing of the magnetos.  If you have a bad mag, it can either fail on you, or the timing will be off, producing a rough engine symptom similar to what a fouled plug will do.  The mistiming could cause damage to your engine, so in that sort of situation, it's not a bad thing to shut off the bad mag, run on one, and land as soon as practical.

http://flighttraining.aopa.org/magazine/2004/August/200408_Departments_Learning_Experiences.html

I concede the point because now it makes sense.  It's still wouldn't be your FIRST solution necessarily, but I can see now where you could have a situation where turning off one mag and flying on the remaining good one would be a viable solution.  But I also agree with Flying Pig, flying on one mag is really more of a land as soon as practical situation, not an emergency and have ATC clear the runways and roll the fire trucks situation.

I tip my hat, and thank you for the opportunity to learn something new.

[Flying Pig]

Ill check it out.  Thanks.   I think the issue here is the differentiation between a bad being an Emergency Procedure.  Another procedure the writer mentions is that he checks his Mags every 20 minutes.  Ive heard of people doing that, but Ive always been of the idea that if there are no indications that there is an issue, you don't need to be shutting things off during flight just make sure it will turn back on.  I see that concept the same as when I teach a student to pre-flight.... You DONT need to grab on to things and shake them to make sure the piece is still attached! 

[jeders]

Another procedure the writer mentions is that he checks his Mags every 20 minutes. 

I do this also, but mostly because my instructor likes to take away my engine about that often. For the Dakota, switching mags is the second to last item on the engine loss EP checklist tight before 'randomly start moving levers and knobs hoping the engine will restart.'

[Flying Pig]

Im just curious how good of an idea this is when you start flying high performance pistons.  I dont mean "HP" as in the FAR definition, I mean things like a T206, P210s, Matrix, etc etc.  The 206 I used to fly had the IO-540/310HP.  intentionally turning off a mag as part of a routine 20 min check seems like it would make her mad.  You get all trimmed up, auto pilot and everything running as toasty as a fire on christmas morning, I wouldnt advise switching off the mags every 20 min. Now you add non-pilot passengers.  I personally dont know any working pilots who do that as a matter of any 20 min scan.  Lets face it sometimes what we learn in flight school just needs to stay at flight school.  I think the switching off mags every 20 minutes is probably one of those things. 

[jeders]

Lets face it sometimes what we learn in flight school just needs to stay at flight school.  I think the switching off mags every 20 minutes is probably one of those things.

I couldn't agree more. My point was more that switching off mags as part of running an established manufacturer provided checklist is ok. However, switching them off just as part of a routine cross-check on a long distance flight is a bit sketchy to my inexperienced mind.

[Flying Pig]

The only place Ive seen it mentioned is AFTER your engine has already failed.  At that point... who cares.   Ill need to research a couple of my POHs and see what it talks about with rough running Mags. 

[C/SrA Ravlin]

I was taught this by a good pilot friend who I have flown with in his 150... I do not mean to run the engine at higher rpms but to run the magneto that runs better (higher rpms) instead of the rough running one. This information has been passed down the chain from my friends great grandpa who flew in WWII. I will check a few pohs that I know of to find the real procedures. One thing I do know is that planes have 2 magnetos for a reason, this is to keep the plane going if one is not working. I will do some research this week and see what I find in the poh of a few aircraft and will talk with my instructor...

[Flying Pig]

Good discussion.  Just be careful of friends passing down family secrets when it comes to flying.   You dont need to check a few POHs.  Just check the POH for the airplane you are training on and see how its discussed in the plane YOU are flying today.

[Cliff_Chambliss]

I was taught this by a good pilot friend who I have flown with in his 150... I do not mean to run the engine at higher rpms but to run the magneto that runs better (higher rpms) instead of the rough running one. This information has been passed down the chain from my friends great grandpa who flew in WWII. I will check a few pohs that I know of to find the real procedures. One thing I do know is that planes have 2 magnetos for a reason, this is to keep the plane going if one is not working. I will do some research this week and see what I find in the poh of a few aircraft and will talk with my instructor...

While the "old School" may have some nuggets of wisdom there are also many Old Wives Tales (OWTs).  Flying on the Step, Never fly over square, etc.  Even Ernest K. Gann one of the great aviation authors talks of (in the 1930's) intentionally causing an engine to backfire to clear carburetor air intake icing I don't think anyone would even consider that today.  Also, my father's old Operations Manual from Pan American Airways days in South America even discussing the retracting the landing gear on short fields to avoid running into trees (lets float that idea past the FSDO and see how far it flies).  My point is that all thing aviation are fluid and are always changing.  What may have been a good idea or even gospel in days past may have no place in todays world.  The best I can suggest is always ask "Why is this so?  What makes this a good idea?" and anytime the answer is "because that's the way it's done, It's always been done that way" or variations thereof, then file the idea away for later bar bets or trivia but don't carry into the cockpit.

NOTE:  "Flying on the step"  some old timers would say to get maximum performance climb to 200 feet above your altitude and then do a shallow dive to target altitude and trim the plane.   TODAY:  We teach Pitch-Power-Trim at the level off. PITCH to level flight, POWER leave power on until you reach the desired airspeed, TRIM adjust engine and trim to maintain level flight.
"Flying Over Square"  Old timers would preach never let manifold pressure (in in) exceed RPM.  TODAY:  Check the airplane performance charts.

NOTE 2:  Watch out for OWT's.  If it sounds odd, strange, weird, challenge the teller.  I tell all my students to challenge me if I say something that just doesn't make a lot of sense.  If I can't show it to them in the proper publications (someone else's handouts/notes don't count.  Must be FAA or equivalent publication)  then it's opinion, and that particular period of instruction is free.  However, If I show them the printed word, they buy me a soft drink.

 

[Flying Pig]

Radials vs modern engines.

[A.Member]

Good discussion.  Just be careful of friends passing down family secrets when it comes to flying.   You dont need to check a few POHs.  Just check the POH for the airplane you are training on and see how its discussed in the plane YOU are flying today.

:clap:

I agree with everything Flying Pig has stated here and in earlier posts. 

He's being much more diplomatic than I'll be.  Again, I don't know everything (or even most things) but some of the stuff I've read here just baffles my mind. I'd even go so far as to call it stupid.

[docsteve]

I've read this post beginning to end and am somewhat confused, but nevertheless I have a couple of points to make.

1) I agree that a mag check should never be done in flight ("stress" as the OP said IIRC).  However . . .

2) A rough engine may be the result of a failed magneto, and a mag check would be necessary to isolate the failed mag (e.g., the Slick mags have a habit of coming apart, which does bad things to the engine's performance while that defective mag is still operating).  I think that that has been made clear already.

3) "Getting the plane on the ground" (if I got the quote right) means, in the FAA's terms, "as soon as practicable."  While "practicable" means a suitable landing site (e.g., an airport capable of handling the aircraft in question), it also means "as soon" as possible, so it means at the first suitable landing field: remember that the aircraft is certificated to fly on two mags, not one, and any prolonged operation with only one mag functioning is an FAR violation (and a mag failure would rquire -- if IFR -- nofication to ATC under 91.183[c]).

4) About carb heat, the sequence described earlier seems somewhat off.  Carb ice causes the engine to run at a lower RPM, not necessarilly roughly; applying carb heat reduces RPM further, then -- if ice were present -- the engine sounds like it is about to explode as the water (the melted ice) runs through the cylinders (not unlike my '73 'Vette running on regular gas, a knocking sound), then the RPM surges.  I've gotten carb ice on climb-out in a 172 and just watched as the RPM very smoothly dropped-off.

It always pays to be a bit scared of the machine and not push the envelope, but it also pays to remember that at times you still wind-up flying -- scared -- by the seat of your pants.

Steve