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#11
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I can't find it right now, but Lycoming had a publication in which they
advised against going to low prop pitch for deceleration of the airplane. They said it caused detuning of the dynamic counterweights on the crankshaft ("harmonic balancers"?) and was the demonstrated cause of damage to certain of their engine models. Although my engine was not listed in the affected models, it seems that the same principle applies, and I have avoided going to the high RPM setting until power is reduced on final, for engine protection as well as noise. Supplement your printed checklist with GUMP checks, including one on short final ALWAYS. Stan "Mitty" wrote in message ... I've been taught to set the prop to high RPM on final, but I don't like this very much because then, when I run my checklist for the first time on downwind, I have to leave one item "open." So what's wrong with doing it on downwind? (This in a Cherokee 6 or and Arrow) It seems to work fine, does not disarrange the engine, etc. I suppose there is some small noise increase, but hardly much. So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with doing it on downwind? TIA |
#12
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On Sun, 21 Nov 2004 23:51:25 GMT, Mitty wrote:
I've been taught to set the prop to high RPM on final, but I don't like this very much because then, when I run my checklist for the first time on downwind, I have to leave one item "open." So what's wrong with doing it on downwind? (This in a Cherokee 6 or and Arrow) It seems to work fine, does not disarrange the engine, etc. I suppose there is some small noise increase, but hardly much. So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with doing it on downwind? TIA Full forward (high RPM) is in case of a go around. Going high pitch mid-field will create a really loud racket on the ground. Waiting until short final is too late in my opinion since we're human and can forget things. To avoid this I go full forward (high RPM) when I make my initial power reduction (generally abeam the numbers). This causes no noise increase, and time for me to double check as I fly the pattern. Hope this helps. z |
#13
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Do you do a final gear check on final? If so, then how much extra work is it to push the prop to forward on final? This will only become an issue if you are performing a go-around *and* you forget to push the prop forward. Even if you forget the prop on final, I don't see how you can forget it again on a go-around. The go-around procedure calls for everything forward, and you will catch it if the prop is out. Going prop forward after the governor has hit the limit is a good practice. It makes less noise, and it demonstrates that you are smooth at the controls. zatatime wrote in : On Sun, 21 Nov 2004 23:51:25 GMT, Mitty wrote: I've been taught to set the prop to high RPM on final, but I don't like this very much because then, when I run my checklist for the first time on downwind, I have to leave one item "open." So what's wrong with doing it on downwind? (This in a Cherokee 6 or and Arrow) It seems to work fine, does not disarrange the engine, etc. I suppose there is some small noise increase, but hardly much. So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with doing it on downwind? TIA Full forward (high RPM) is in case of a go around. Going high pitch mid-field will create a really loud racket on the ground. Waiting until short final is too late in my opinion since we're human and can forget things. To avoid this I go full forward (high RPM) when I make my initial power reduction (generally abeam the numbers). This causes no noise increase, and time for me to double check as I fly the pattern. Hope this helps. z |
#14
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"Mitty" wrote in message ... I've been taught to set the prop to high RPM on final, but I don't like this very much because then, when I run my checklist for the first time on downwind, I have to leave one item "open." So what's wrong with doing it on downwind? (This in a Cherokee 6 or and Arrow) It seems to work fine, does not disarrange the engine, etc. I suppose there is some small noise increase, but hardly much. So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with doing it on downwind? TIA There's ALWAYS a problem if one learns to do something mechanical without understanding the reason for it. Not recommended. Here are some possibilities, pro and con: If your engine quits, you want the propeller the prop already at low rpm, to lower drag. On the other hand if you have to abort the landing and go around, you want it on high rpm for added low-speed thrust. Always ask WHY? (You may have to try several instructors until you get a reasonable answer.) Don't just memorize checklists mindlessly. John Lowry Flight Physics |
#15
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On Sun, 21 Nov 2004 23:51:25 GMT, Mitty wrote:
I've been taught to set the prop to high RPM on final, but I don't like this very much because then, when I run my checklist for the first time on downwind, I have to leave one item "open." So what's wrong with doing it on downwind? (This in a Cherokee 6 or and Arrow) It seems to work fine, does not disarrange the engine, etc. I suppose there is some small noise increase, but hardly much. So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with doing it on downwind? It depends on the airplane and prop, but it increases noise and drag. Drag isn't bad if you wish to slow up and it's not at all uncommon to wish to do so on down wind. OTOH that is not a problem with either the Arrow or Cherokee family. If you go full RPM in a Bonanza or Cessna 210 with a 2 blade prop, the neighbors will not like you. With those there is a big increase in noise until the MP is back to the point where it's controlling the RPM. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com TIA |
#16
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On 21 Nov 2004 20:04:44 -0600, Andrew Sarangan
wrote: Do you do a final gear check on final? Yes If so, then how much extra work is it to push the prop to forward on final? For my philosophy the final check, should be just that - only a check, no work unless an error has occurred. Subtle I'm sure, but the less "work" on short final the better IMO. This will only become an issue if you are performing a go-around *and* you forget to push the prop forward. Even if you forget the prop on final, I don't see how you can forget it again on a go-around. The go-around procedure calls for everything forward, and you will catch it if the prop is out. If in your mind you think you pushed it forward you'll probably realize it isn't only after the throttle has been pushed full forward. (I know not an absolute, but more likely than not for an average person). If it does happen you'll be way "over square" and potentially do alot of engine damage. Not withstanding the damage potential, you could get alarmed by the condition, fixate on rectifying it, and relax the pitch control. In heavier airplanes you could get enough of a pitch up that it's hard for a person to recover. I'm not being sexist, but I had this happen to a woman I was flying with, lets just say it was a good learning experience for her. g This was in a 172RG so heavy is a relative term. Going prop forward after the governor has hit the limit is a good practice. It makes less noise, and it demonstrates that you are smooth at the controls. Now i"m confused. It seems like we agree. I may not have been clear, or may have missed something, but this is what I meant when I said to go full forward after throttle reduction. z |
#17
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Mitty,
So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with doing it on downwind? Yes, noise, noise. Just listen to a Bonanza turning on the chain saw on downwind once, and you'll never again say it's only a "small noise increase". The effect, while differing from type to type, is huge. If you want airports to stay open, don't do it on downwind. Also, in case of a go-around, it is probably anyway a good idea to think in terms of "all levers go full forward" rather than just "throttle full forward". -- Thomas Borchert (EDDH) |
#18
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In article , Mitty wrote:
I've been taught to set the prop to high RPM on final, but I don't like this very much because then, when I run my checklist for the first time... Simple - change your checklist. They aren't set in stone. In any case, forgetting the prop (especially on a plane like an Arrow or Cherokee 6) is hardly critical - in the case of a go-around it's easy enough to grab all the controls and push them forward when they are arranged like this. -- Dylan Smith, Castletown, Isle of Man Flying: http://www.dylansmith.net Frontier Elite Universe: http://www.alioth.net "Maintain thine airspeed, lest the ground come up and smite thee" |
#19
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Why even worry about it unless you're going to go around?
"Mitty" wrote in message ... I've been taught to set the prop to high RPM on final, but I don't like this very much because then, when I run my checklist for the first time on downwind, I have to leave one item "open." So what's wrong with doing it on downwind? (This in a Cherokee 6 or and Arrow) It seems to work fine, does not disarrange the engine, etc. I suppose there is some small noise increase, but hardly much. So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with doing it on downwind? TIA |
#20
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So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong
with doing it on downwind? 1. Yes. 2. Rote procedure. 3. Noise. I had this brought home to me during Mary's biennial. I was working in the hangar while she was coming into (and going out of) the pattern, and, boy, could you tell when she pushed the prop control forward on a fast downwind. That Lycoming O-540 just growled. Now, personally, I LIKE that sound -- but I understand there are those in the flight path who don't. Since we have to live with those folks, it's a good idea not to give them the ammo with which to shoot us down. Noise abatement is serious stuff when your community is not 100% for having an airport in the first place. We now don't push the prop full forward until we're on final, when the airspeed and MP is already so low that it makes no audible difference. -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" |
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