Backfire During Runup

BrianNC said:
@eman1200 who did you train with there? I had a couple of flights there in an Arrow with Jon Long of Long Aviation in '06. I think he's moved his operation to Rock Hill now.
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Small world. I bought my Cherokee from Jon back in 04. 2 years later my dad found a Cherokee for sale that he ended up buying from him also.
 
CC268 said:
Yep. Select left mag. But keep in mind my panel was completely redone so in 2010 so it may not be the same as original...
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You're doing it right. It's different than all the other aircraft since the starter button is separate from the ignition keyswitch. As noted in earlier, when the keyswitch has a Start position, that automatically uses only the coupled magneto, even though it's actually past the Both setting.

Interestingly, Piper went back to this with the Archer III. It has no keyswitch and separate switches for Left and Right magnetos. Once again, you have to remember Left only for start, then Right after start.
 
Yeah, but Cherokees....nah, I won't go there.
 
Rod Machado refers to this as his student 's click-click-click-click-bang mag check. If you turn it to off, either let it die or pull the throttle to idle before turning it back on.
 
CC268 said:
Na I start mine literally with the key on left mag and then press the button and bam. Maybe I’ve been doing it wrong the past 130 hours?? Just doing what my checklist says
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^^^^ THIS ^^^^^^ Start it on both or R and you can blow your starter to Mars
 
flyingron said:
Rod Machado refers to this as his student 's click-click-click-click-bang mag check. If you turn it to off, either let it die or pull the throttle to idle before turning it back on.
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Why would the throttle be anywhere but close to idle?
 
Mooney Fan said:
Purchased a 67 Cherokee 140 last week. Put about 8 hours on it, and still getting used to starting on the left mag, as all other planes I have flown are started on both. Well, I didn't switch to both after start and taxied to the run the active. Then of course it happened...... When I went what should have been 2 over to check the right mag, I actually went 2 over and turned off the ignition. I immediately went back to both and got a backfire. Since then I have put 2 hours on the plane with no adverse effect.

Some have suggested I have the baffles inspected. Just wondering if anyone has any input on this.

Thanks
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You definitely want to get the baffles inspected.
 
'76 140 I instruct in starts by inserting key, turn all the way to the right, and push in to start. The '69 Arrow I'm not sure, only flown it once, well actually watched a guy fly it for check out.
 
SkyDog58 said:
Most mag checks are done around 1800 RPM or so. That’s far from idle.
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Sorry, I read that wrong.
But that brings up another question, why not idle? if it is going to miss, it will do it at all RPMS.
 
I've noticed it's easier to recognize the mag drop at higher RPM than it is at idle so for me that would be why.
 
EdFred said:
I've noticed it's easier to recognize the mag drop at higher RPM than it is at idle so for me that would be why.
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Mag drop vs it just quits.

If it is dropping a cylinder would it be more noticeable at high RPM or low RPM?
 
Tom-D said:
Why would the throttle be anywhere but close to idle?
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Because you typically do mag checks at an elevated power setting, i.e., 1700RPM for the Skyhawk. 2200RPM on my IO-550.
 
flyingron said:
Because you typically do mag checks at an elevated power setting, i.e., 1700RPM for the Skyhawk. 2200RPM on my IO-550.
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Think you are late to the gate, read post 57. :)
 
POH for my model Cherokee 140, calls for 2000 RPM for run-up and Mag check. The RPM is also needed for oil pressure, suction etc checks. I know some pilots who check their carb heat at idle since on approach when near, or at idle, they are concerned carb heat could choke the engine.
 
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