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Originally Posted by fodrv7
However, I no longer exercise the prop, as recommended by John Deakin, who advises that procedure is only required by thousand plus HP recips. Pete.
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That John Deakin. yea why check the prop.
Hey why check the ignition for that matter, it always works. Carb heat, what they hey, its not sitting on the ramp must still work. Sure skip the prop check, why check it. Hey lets forget a control check while we are at it, they are always free and correct as well.
I think John Deakin has a better way to do everything. Here is a AOPA article that Hartzell, McCauley contributed to.
http://www.aopa.org/asf/publications/sa06.pdf Check page 6 - Prop exersise.
Respecfully I think John Deakin is 100% wrong. Props and govonors are complicated and need to be checked.
You check the ignition at approx 1700 rpm, where the pressure is high enough to load the ignition. While you are there, why NOT check the prop? It takes 5-10 seconds to pull the prop back slowly and check it once or twice. As soon as the rpm starts to change, push the control back to high rpm. Why not?
Exercise that prop; you will avoid or reduce surge on take off, which is not desirable or good. Pete you allude to some surge. In cold weather it more critical to get warm oil to the prop. Failure to do so may result in an engine over speed.
Some may think you're wearing out your prop or governor by testing it? Well may be its better to get oil and grease moving in the prop, governor and lube the seals under a lower load, getting ready for 100% power and rpm?
All these procedures are determined by
designers,
engineers,
test pilots and the
FAA. John Deakin seems to have disdain for either the procedure's or the people that write them. His standard argument is engineers, pilots and FAA does'nt know what they are talking about and procedures are casually written with no thought, based on trivial reasons, like they only apply to large radials. (WHAT?) I'd like to see the proof. Could John possibly be the one missing something?
Why do we do prop checks:
Forces oil into the prop hub
Prop is responding normally @ min governing rpm **
Prop returns to low pitch
Controls and lines functioning
**( Broken or out of adjusten cable, blocked passage or failed govonor. The later two can lead to overspeed and engine damage.)
Granted a DC-3, B-17 or B-25 has more to check with a feathering circuit and so on, but this does not mean a little prop on a little Lyc is no less important or less deserving of a functional check before takeoff. What if 1,700 rpm normally gives you a 100-200 rpm drop but during check nothing? I don't know? I'm not a prop expert but call you prop and gov manufacture and ask them. I am sure they will tell you to check the prop during run up. Than tell them about John Deakin. John who?
It gives me a funny feeling accepting an experts opinion that's totally different than every FAA approved flight manual. John may have a point, but there's trade offs to no checking. I have seen real smart pilots not do procedures, because they found a better way. at times it led to problems at some point, but sometimes they get a way with it. They may be lucky and never have an issue. It's like run-up. Roll the dice, why do it at all, its always good.
The day may never come, but if that day comes, when you pull on your prop during run-up and nothing happens, it may be an indication of a small or large problem! Don't you want to know before taking off?
There is no need to go crazy with a prop check and yank on it abruptly or lug the engine down too much. I would recommend following the normal procedures. That's just me. Call me crazy, following normal procedures. What's up with me. The argument that "Its just for big high HP radials" is unconvincing. I will always check the prop on the first flight of the day. There are times on rough strips with rocks I'll not check my prop to avoid blade damage, but thats not normal. Just my 0.02 worth.
MT prop governor - governing rpm range?
Linear Mode
