Mag Drop

[kortopates]

2 hours ago, DonMuncy said:

It is "belt and suspenders". If the P-leads are good, you should be safe even with fuel available. If you shut it off with the mixture cut-off, you should be safe even with bad P-leads. But with both, you have redundancy.

 

Not true!! Not for fuel injected engines! Remember what happens after you shut down a heat soaked engines - what happens to the fuel in the lines - where does it bleed into??? This is why its so important to test the p-leads on every shutdown before you get out and push your plane back. So often before we push it back, we move the prop out of the way. When we do, we should always move it backwards to prevent an impulse mag from engaging and thus firing if we should have a bad p-lead that is not grounded. (don't worry about the OWT about hurting your vacuum pump doing that - its a myth.)

[Guest]

7 hours ago, Skates97 said:

Thanks, I appreciate the info. I think I will add that to my shut-down checklist.

Richard,

A "live mag check" is normally taught as part of modern flight training.  Broken  magneto "P" leads or defective switches are normal causes for a live magneto at shut down.  

Clarence

[Bob_Belville]

11 hours ago, DonMuncy said:

Killing the engine with (lack of) mixture is a safety measure. If you kill it by shutting off the fuel, it is unlikely to have residual fuel available to start the engine if someone accidentally turns the prop, and the P-leads are defective.

Additionally, we want to know that the big red knob will indeed completely cut off fuel to the engine.

[201er]

Duplicate 

Edited February 6, 2017 by 201er

[201er]

8 hours ago, kortopates said:

Not true!! Not for fuel injected engines! Remember what happens after you shut down a heat soaked engines - what happens to the fuel in the lines - where does it bleed into??? 

I agree, but even with that little bit of fuel and a hot spark, what are the chances of it firing if you turn the prop once? Very small.

Regardless, I always turn the prop like I'm hand propping in case it fires.

[ArtVandelay]

I agree, but even with that little bit of fuel and a hot spark, what are the chances of it firing if you turn the prop once? Very small.

Regardless, I always turn the prop like I'm hand propping in case it fires.

Especially considering how hard it is to hot start these engines.