Jaybird180
Final Approach
You're flying behind a Single Engine Constant Speed Prop and the checklist calls for a MP/RPM reduction during the climb. When do you do this and why do you choose that point in time?
Initial Climbout power reduction
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texasclouds
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Safe altitude, transitioning to a cruise climb
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Chrisgoesflying
1,000 ft AGL for me, same time I turn off the fuel pump. POH doesn’t say when exactly to reduce power, it just says “when sufficient altitude has been gained” to reduce power to climb power. I picked 1,000 ft AGL as that’s when i turn off the fuel pump so it feels natural somehow.
MauleSkinner
Touchdown! Greaser!
Depending upon how fast you climb, the MP can reduce itself at an adequate rate.
Larry in TN
En-Route
Generally, just a small reduction in RPM unless the AFM or engine's manual has specific limitations listed.
ateamer
Pattern Altitude
Who wrote the checklist? The manufacturer’s engineers or someone who trained at the old wives’ tales school of flying?
If it was in the POH, I wouldn’t reduce power after takeoff until the last second allowable by the manufacturer. I want altitude in the shortest time possible, sometimes in the shortest distance, depending on the geography.
If it was in the POH, I wouldn’t reduce power after takeoff until the last second allowable by the manufacturer. I want altitude in the shortest time possible, sometimes in the shortest distance, depending on the geography.
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Velocity173
My checklist in the Glasair doesn’t specify but I do the 1,000 ft reduction as well. 2,700 rpm until that, then 2,500 & 25. Go from about 1,800 fpm to 1,200 fpm so not a huge difference.
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Chrisgoesflying
My POH states it in the Comanche. It doesn't say when and to what - it just says reduce to cruise climb power once at sufficient altitude. At full power and close enough to sea level I climb at 1,500 fpm. I also reduce to 2,500/25 at 1,000 ft AGL at which point I still climb at 1,000 fpm. Once at 2,500 ft AGL I lower the nose to 500 fpm to get higher airspeed. I usually don't touch the MP after reducing to 25 as by the time I'm at cruising altitude it's low enough naturally. Once in cruise I pull RPM back to somewhere between 2,300 and 2,400.
Steamflyer
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If the POH does not mandate a power reduction, I have found that climbing at full power, while reducing fuel flow appropriately as altitude increases (talking NA here) leads to the fastest climb, least fuel burned, and coolest engine.
If there are restrictions, then follow them of course.
If there are restrictions, then follow them of course.
Deakin addresses this.
www.avweb.com
Pelican's Perch #19:Putting It All Together
In recent columns, John Deakin has explained all you need to know - and more than some of you wanted to know - about the three engine controls: throttle (MP), prop (RPM), and mixture. Now, AVweb's resident pelican puts all that theory into practical perspective by taking you through each phase...
www.avweb.com
RussR
En-Route
I see no reason to make a connection between power reduction for cruise climb and IFR departure turn limitations.
MIFlyer
Pattern Altitude
My stc says pull back after one minute. I pull the gear up around 500’, pitch for slower climb rate and pull prop and throttle back for cruise climb. I’m still working on it but my no obstruction airport that probably means 45 seconds from takeoff roll to power reduction
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I didn't.
Ed Haywood
En-Route
I was taught 1K AGL, with the logic being failure is more likely when you change power settings, so don't touch anything below pattern altitude. Ok, whatever.
I generally run WOT up to cruise altitude and use pitch to manage temperature.
I generally run WOT up to cruise altitude and use pitch to manage temperature.
RussR
En-Route
400 ft is the minimum IFR departure turn altitude. If you didn't get that value from IFR procedures, where did you get it from?
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Albany Tom
Only think I'll add is that I think I've seen some setups where full power takeoff was permitted by POH for something like 5 minutes, but then to reduce RPM to be at or below X, and that X was a redline speed marked on the tach. Not positive I've seen that, but I have read limits that were by minutes, not altitude. OP also mentioned a checklist, but didn't specify if that was a manufacturer checklist or something someone put in the plane by the owner. Sometimes those checklists don't line up to the POH.
wilkersk
Pattern Altitude
Depends on the airplane. But usually I adjust for Vy and cruise climb as soon as I’m above the treetops or other obstacles in the immediate area. It’s better for the engine and reduces perceived aircraft noise on the ground.
We have one particular pilot that takes off and flies what seems like the full length of the East Sound out of Orcas island with full pitch. He really winds that thing up. You can hear him all the way across the San Juans sometimes. I think he does it just to annoy the people living in the nice houses along the sound.
Your POH calls for a power reduction at 400 ft??? I'm curious what plane and engine as that seems VERY low and doesn't make any sense?
I know that some planes have Yellow arcs and also have limitations on how long you can be at Max RPM. But they're pretty limited. In most planes there's no reason to make any power changes until a bit after you've leveled off at your cruise altitude and have accelerated to your cruise speed.
Steamflyer
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Steamflyer
Think poster said "I was taught..." - i.e. some sort of handed down from CFI-to-CFI or pilot-to-pilot procedure. And since 400' is generally tied to IFR, that's an untenable altitude to be fussing with power controls having just entered IMC (potentially).
Steamflyer
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Suspect the noise is not perceived, it's heard. Transonic tips on big bore 2700 and 2800 rpm redline engines make a lot of noise. These aircraft may be better neighbors with a 200 rpm early power reduction. Think many a Bonanza. Or a T-6. Not super quiet.
Please provide data on "it's better for the engine."
Shepherd
Final Approach
When reducing power won't result in flying into anything.
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Chrisgoesflying
400 ft seems low. I know some swear by never reducing power in climb - i think it makes sense to do, especially if the poh calls for it but not too low! As some have mentioned, you want to get away from the ground as fast as possible to give you options in case of an issue.
Steamflyer
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Steamflyer
Always need to differentiate between mandated by POH due to limitions or an STC, and allowed by POH for fuel savings, noise abattement, or otherwise. In the absence of limitations prefer to limit power setting changes to the minimum.
Larry in TN
En-Route
While complying with all AFM and engine limitations, reduce power once you have enough altitude to safely handle an engine failure. The altitude at which that occurs will vary from airport to airport.
Steamflyer
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Why not as part of the level off/cruise checklist? Is there an implication that full power is more likely to cause a failure, or that reducing might, or neither?
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Chrisgoesflying
Not sure it does but I can imagine reducing power and not running it at full power for too long is good for the engine long term? Same reason I turn off the fuel pump at 1,000 ft AGL - less run time, longer life. Also, cabin noise is much lower when reducing power to cruise climb which makes for a more pleasant ride.
You're right about that. 1,000 ft AGL is my standard but I've had full power in until 2,000 ft. at times when circumstances called for it.
My TSIO-520R is limited to full rated power (everything firewalled) for 5 minutes. With a moderate payload I am at 500' pretty quick climbing at 100kts. I pull off of 'full mil' power at 500' back to 30-31"/2500/120kt IAS and am still climbing at 700 fpm. I suppose I could keep it a max power a bit longer but I can reach 1000' pretty fast pulled back, so I do to reduce engine stresses.
Some aircraft have published limitations for full power. Many (including my Bonanza) don't. John Deakin's advice (see @Racerx 's post above) makes the most sense to me:
Also from this John Deakin article:
And:
Bottom line: What appears to be intuitively good for an engine isn't always good for the engine. Less power isn't always better for the engine.
- Martin
An RPM reduction makes sense over noise sensitive areas. Otherwise, it's full throttle and max RPM.
Also from this John Deakin article:
And:
This remains valid in the climb, too. Retarding the throttle lever deprives the engine of that extra fuel it needs to keep the mixture on the far rich side.
Bottom line: What appears to be intuitively good for an engine isn't always good for the engine. Less power isn't always better for the engine.
- Martin
It's long, but well worth the read. I'm glad avweb has archived all of Deakin's articles.
Larry in TN
En-Route
Most of these engines do have a limitation at max power, often indicated by the top of the green arc on the tachometer. Even without that, 2400 or 2500 is a lot quieter than max and should be easier on the engine over the long term.
As far as MP, leave it at full unless limitations require a reduction. Most of the normally aspirated engines do not.
In all cases, the AFM and engine manual are controlling, not some rule-of-thumb that your CFI may have taught you two decades ago.
Kind of why I was asking what plane/engine to see if there was any truth or if it was just a REALLY BAD old wives tail kind of teaching.
Hopefully he'll fly with another CFI(I) in a Flight Review or IPC that pushes on the WHY part of the early power change.
I could see reducing power if there were noise abatement procedure. But as far as "It's better for the engine..." where did you get that?
I get the concept of lower RPMs over the life of the engine may be better due to reduced cycles, but that is a cruse discussion. In a climb you have the option of using full power for a short period of time. Or, you can slightly reduce the power, which doesn't really take that much stress off the engine, and then take a longer time to climb keeping the engine at this higher climb power settings.
I reduce power when I no longer need full power before I exceed the max duration for takeoff setting. I'm not sure why this is up for much discussion. Typically, you get two or five minutes. Once I clear terrain, I set a normal climb power.
Steamflyer
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Steamflyer
Many to most installations do not have a “for take-off only” limitation. A few do of course. On the balance I thought this thread was canted towards those that do not.
wilkersk
Pattern Altitude
You accelerate to Vy (in most aircraft) which gets you more cooling air, gets you to cruising altitude faster and therefore gets you to level lean and clean flight. It would seem to me pulling a few RPM off as you lower the nose slightly for Vy is a good thing to do. Why wouldn’t you want to do that?
If you don't have a max continuous, then you can run Full Rental Power through then entire flight.
