1st Power Reduction in the Climb

Jaybird180

Jaybird180

Final Approach
Joined
Dec 28, 2010
Messages
9,036
Location
Near DC
Display Name
Display name:
Jaybird180
On CS Prop airplanes, the procedures usually include reducing power during the climb after takeoff and also reducing prop RPM.

My first CS Prop airplane I transitioned into was the DA-40 and this was the practice. Thinking about it this morning, I recall that I opted to not make any changes until I thought we had reached a safe altitude, which was about TPA or sometimes just after pushing the nose over to not bust the Bravo shelf.

My rationale was that changes could induce a powerplant failure and if it's working fine now, leave it alone. This is counter-intuitive to the fact that the engine is working hardest at this setting and that pressure and temperature are the biggest enemies to a happy engine.

Are there merits to delaying the power reduction? How about carry that thought to the extreme and reduce power immediately after leaving ground effect? How about at Vr?
 
Personally, I don't like to change things until I am a little higher - like passing through 1000' AGL for the reason mentioned - there is a lot of debate on this, but my personal experience with things of an engineering nature are mechanical things seem to fail more when changing settings.

Very few GA engines can't handle Max T/O power up to TPA. Even the airplanes I've flown that have takeoff power limits can still be flown up to TPA before reducing power.

If you are that concerned with takeoff power being too stressful, I would rather use a reduced takeoff power setting than change it while climbing out of ground effect. A lot of warbird operators use reduced power settings for takeoff these days, but even that has started more than a few internet fights.
 
Fearless Tower said:
Personally, I don't like to change things until I am a little higher - like passing through 1000' AGL for the reason mentioned - there is a lot of debate on this, but my personal experience with things of an engineering nature are mechanical things seem to fail more when changing settings.

Very few GA engines can't handle Max T/O power up to TPA. Even the airplanes I've flown that have takeoff power limits can still be flown up to TPA before reducing power.

If you are that concerned with takeoff power being too stressful, I would rather use a reduced takeoff power setting than change it while climbing out of ground effect. A lot of warbird operators use reduced power settings for takeoff these days, but even that has started more than a few internet fights.
Click to expand...

I agree. I have also heard of (not sure of its validity) an increased risk of engine failure upon the first power change, so I leave full takeoff power until I'm at an altitude where I'm all but assured a safe return to the airport.

The alternative is to stay in ground effect at max power and then zoom climb up to pattern altitude...... ;)
 
Jaybird180 said:
On CS Prop airplanes, the procedures usually include reducing power during the climb after takeoff and also reducing prop RPM.

My first CS Prop airplane I transitioned into was the DA-40 and this was the practice. Thinking about it this morning, I recall that I opted to not make any changes until I thought we had reached a safe altitude, which was about TPA or sometimes just after pushing the nose over to not bust the Bravo shelf.

My rationale was that changes could induce a powerplant failure and if it's working fine now, leave it alone. This is counter-intuitive to the fact that the engine is working hardest at this setting and that pressure and temperature are the biggest enemies to a happy engine.

Are there merits to delaying the power reduction? How about carry that thought to the extreme and reduce power immediately after leaving ground effect? How about at Vr?
Click to expand...
Depends on the powerplant for me. If it's something like an IO-360, I'm probably going to leave all the power (unless the POH says otherwise) until cruise.

If it's something like the TSIO-550, I'm slowly working the manifold pressure back to 35" pretty quickly after takeoff, definitely below TPA, unless I'm worried about terrain or trying to get through an ice layer quickly.
 
Some engines, mine included (Lycoming O-360 A1F6D), have a setting that enriches the mixture with full throttle for additional cooling in the climb. It is a mistake to pull the throttle back before cruise altitude. Always full throttle for the climb. But that's just some engines. Other engines may require different procedures.
 
The general rule followed is 1000 AGL. Basically, climb out, clean up, get above the idiots doing zoom climbs, and then pull the power back. The engine failure at first power reduction is another one I've heard but never seen data to back up.

You're not going to hurt the engine by waiting to 1000 AGL to do a power reduction.

For some engines, just firewall the whole way to cruise.
 
If the CHT's get too high, you will want to go faster for more cooling and/or reduce power. Find a "cruise climb". If the plane has a best glide of 70, its cruise climb is around 90. Depends on altitude and other things too numerous to mention.
 
I go to TPA and above before reducing power. I try to do a Vy-ish climb to 1500 or 2000 agl but at that point I am almost always limited by oil temps. It's just a fact of life in the TR182. Height AGL = options so the quicker I can get it under me the better.
 
I'll leave the throttle full forward but I'll bring the prop back a bit to 2,500 rpm. If a power reduction is going to induce a failure, it's going to be a result of a throttle change, not a prop governor change.
 
John Deakin has a fantastic article on this. I asked this exact question on this forum when I bought my Arrow III. I was taught the "25/25 Myth", but after reading from a lot of users here and john deakin's article, I leave the throttle at full all the way to cruise.

When you reduce to 25/25 you are placing yourself in the prime detonation zone. You are loosing all mechanical advantage on your crankshaft and increasing cylinder pressures to astronomical levels. Wide open throttle sets a throttle-plate/fuel-control relationship where you have maximum fuel for cooling at the high power setting. FUEL is what the engine WANTS and NEEDS at higher settings. As soon as you retard the throttle, the fuel control allows less fuel.

Unless a limitation is specifically stated in your POH (like after 5 minutes reduce to 25/2500), its perfectly safe to stay at full power. In the sue happy culture we live in, manufacturers do everything to protect themselves from lawsuits. If there isn't a limitation I would leave the manifold pressure at full throttle.
 
PPC1052 said:
Some engines, mine included (Lycoming O-360 A1F6D), have a setting that enriches the mixture with full throttle for additional cooling in the climb. It is a mistake to pull the throttle back before cruise altitude. Always full throttle for the climb. But that's just some engines. Other engines may require different procedures.
Click to expand...
Perhaps a silly question, but what engines do/don't? I've heard that advice before from Deakin, but in my IO-470 powered Baron, when I'm taking off from Phoenix or even here in Norfolk in the middle of the day in the hot summer months (OAT above 100F), shallowing the climb and pulling the throttles back is the ONLY way I can keep CHTs below 400F.

Do the IO-470s lack the full throttle enriching, or is it just a factor of the feature not being able to do enough at that OAT?
 
Many engines have a max time in minutes for full power, some folks use all of it, others don't, just don't go over it and you're fine.

For me with a IO520D, I have full power till I'm clear of any obsticals, then I bring her back to 25 squared till I level off, typically that's around 1-2k AGL.



Fearless Tower said:
Perhaps a silly question, but what engines do/don't? I've heard that advice before from Deakin, but in my IO-470 powered Baron, when I'm taking off from Phoenix or even here in Norfolk in the middle of the day in the hot summer months (OAT above 100F), shallowing the climb and pulling the throttles back is the ONLY way I can keep CHTs below 400F.

Do the IO-470s lack the full throttle enriching, or is it just a factor of the feature not being able to do enough at that OAT?
Click to expand...

Yikes! I got zip experience with barons and that is a significant OAT, but maybe check baffles? add some cowl louvers? Seeing over 370 in climb or 350 in cruise has me going over my cooling system and climb profile.
 
Last edited:
I'll leave full power in until about 500 ft. then power back.
 
Deakin's advice is not one size fits all, not entirely accurate, and it can burn a ton of fuel depending on the plane. It mostly refers to Continentals that have a strong tie to fuel flow with throttle position rather than manifold pressure/airflow. However to be frank, I've never seen an engine show more propensity to detonate at part throttle than full throttle. 421s, RAM 340s, etc would be falling out of the skies due to detonation if climb power settings caused detonation.

This is one of the big areas of confusion with some of the modern preachings. There's nothing wrong with pulling power back for climb. There's also no problem with full throttle for climb, unless a limitation says so.
 
EdFred said:
Fixed that. :D
Click to expand...

Your correction is what I normally do in the 310, but not always. For example, the 1500+ FPM climb rate ill get at max continuous (I have a 5 minute limit at 2850 RPM, 2700 max continuous) is too much for my kids' ears. So I'll do a 25"/2300 RPM LOP climb with them for 500 FPM at 160 MPH IAS.

Solo? Wooooohooooo! More power! :D
 
Fearless Tower said:
Perhaps a silly question, but what engines do/don't? I've heard that advice before from Deakin, but in my IO-470 powered Baron, when I'm taking off from Phoenix or even here in Norfolk in the middle of the day in the hot summer months (OAT above 100F), shallowing the climb and pulling the throttles back is the ONLY way I can keep CHTs below 400F.

Do the IO-470s lack the full throttle enriching, or is it just a factor of the feature not being able to do enough at that OAT?
Click to expand...

I do not know the answer to that question, but it very definitely sounds like your engine requires different handling than mine.

CFO (Cardinal Flyers Online) recommends for my plane full throttle to cruise altitude, and by then, MP will be reduced from below 25 anyway, so just reduce RPMs to desired, and adjust the throttle as necessary. But I have a tiny four-banger up front with fairly decent cooling.
 
In the Mooney (IO-360) I keep 2700rpm and full throttle until cruise altitude, then back the rpm down to 2400-2500 depending on how fast I want to go. The throttle remains fully in until I'm passing thru 5000 or so on the downhill side.
 
Just depends on the plane you fly. The swift with a 210 continental has plenty of power, and its pretty loud at the redline RPM of 2800. So I like to pull the throttle back to 25" or a bit less, then reduce RPM to 2500 somewhere about 500'. Still climbs over 1200FPM and its much smoother and quieter.

There is I believe a 5min limitation for that full continuous takeoff power, I would never come close to it as the plane would be at 6000 feet in 4 minutes.

I don't believe there is a limitation against operating it that far over square, that is full throttle and 2500rpm. I used to run the 180hp swift like that, leaving the throttle wide open but dialing back to 2500 somewhere around pattern altitude. However I thought it a wise idea to get in the habit of always reducing MP before RPM, because in some turbo engines you can really hurt them by pulling the prop back before the throttle.
 
Last edited:
Ted DuPuis said:
Your correction is what I normally do in the 310, but not always. For example, the 1500+ FPM climb rate ill get at max continuous (I have a 5 minute limit at 2850 RPM, 2700 max continuous) is too much for my kids' ears. So I'll do a 25"/2300 RPM LOP climb with them for 500 FPM at 160 MPH IAS.

Solo? Wooooohooooo! More power! :D
Click to expand...

Bill Jennings said:
In the Mooney (IO-360) I keep 2700rpm and full throttle until cruise altitude, then back the rpm down to 2400-2500 depending on how fast I want to go. The throttle remains fully in until I'm passing thru 5000 or so on the downhill side.
Click to expand...

I will reduce from max RPM (2575) to 2300 between 500 and 1000 feet, and shallow out the climb for temps, but still WOT until I am in the descent. And that depends on air stability, because my descents usually end up at the top of the yellow, and then the throttle comes back to maintain 500fpm descent. If it's a roller coaster ride, then MP is determined by 500fpm and Va.
 
Bill Jennings said:
In the Mooney (IO-360) I keep 2700rpm and full throttle until cruise altitude, then back the rpm down to 2400-2500 depending on how fast I want to go.
Click to expand...
With an O-360 I climb at full throttle and 2400-2500 rpm. So much for the "oversquare" myth. :D

SAM_0198.JPG


(Of course, it's a fixed-pitch prop, so I don't have much choice!) :wink2:
 
Pilawt said:
With an O-360 I climb at full throttle and 2400-2500 rpm. So much for the "oversquare" myth. :D
Click to expand...

It's not a myth so much as a generalization that's inaccurate for most planes. But it was conservative and easy, which is why people started using it.
 
25"/2,500rpm is horse manure. Don't do it. Ever.

If there is no time limitation, run that damn thing full power all of the way up. If it does have a limitation, observe it.

Deakin's methods are great toward the saying - "Give a man a fish and feed him for a day. Teach him to fish and feed him for a lifetime."

Don't just pull numbers for his articles and apply them to your engine. That's idiotic and he tries to clear out those readers from day 1. If you're one of those readers, just run full mixture everywhere.
 
Last edited:
Depends on the machine really !

We generally do restricted power t/o (34") in our PA34's to save fuel ! Leave it there till 1000 agl and then back to 24"/2400.
 
IrishFlyer1 said:
Depends on the machine really !

We generally do restricted power t/o (34") in our PA34's to save fuel ! Leave it there till 1000 agl and then back to 24"/2400.
Click to expand...

Is that in the POH or did you make it up? Chances are that you are doing more harm than good.
 
I say you can go oversquare by 5. Like 25" and 2000rpm. Nothing wrong with square though. 2500rpm 25" is ok.

You will notice if you are running 2500rpm, 25" and you reduce throttle to 18" as you reduce rpm from 2500 to 2000rpm the manifold pressure goes UP from 18" to 20".
 
I got one of those limitations being written about: 1 minute WOT at max RPM (about 2300 RPM depending upon pitch attitude). Then to 2050 for nearly any MP I want. I have a 1948. The 1949 with the same engine ups the numbers to 1 minute WOT at 2600 reducing to 2300 (if memory serves). (Some say the difference is paperwork. Others forget to make the adjustment and keep all the power in ;) I'm too chicken.)

Anyway, lots of old parts between what I'm touching and the pitch motor / carb. I'll let that alone until TPA - and above all those pine trees below. (Longer if I need to get over one of the local lakes.)
 
What a good discussion. In the IO-540 I fly the POH says 32"/2400 for "Takeoff" and 25"/2400 for "Normal Climb". I've always wondered what altitude to transition during a normal takeoff and climb so I usually do it around TPA.
 
Cpt_Kirk said:
Is that in the POH or did you make it up? Chances are that you are doing more harm than good.
Click to expand...

Its as per the SOP's of the flight school. We've been operating like that for 10+ years never had a issue !
 
IrishFlyer1 said:
Its as per the SOP's of the flight school. We've been operating like that for 10+ years never had a issue !
Click to expand...

Have you seen the MX records or are you saying that because no one has augured in due to an engine failure? The HP/Complex endorsements are being given out like candy and are doing general aviation a disservice.

Learn how to properly operate an engine. You owe it to your passengers.
 
Last edited:
Gucci Pilot said:
I'll leave full power in until about 500 ft. 3 nm from my destination, near TPA, then power back.
Click to expand...

This works great for me, and many others that I know.

Retarding throttle during climb increases your engine temps because you slow down (less fuel AND less airflow through the cowl), plus you climb slower so you're exposed to this bad situation for a longer time.

WOT & Full RPM from the end of the runway to cruise altitude. If high enough (~7000'), only pull back RPM. Push for 500 fpm to descend, and trim away yoke force. Level off and reduce throttle to reach flap speed. Fly a normal pattern and land with throttle at idle.

I'm a recent convert to WOT operation, after talking with a former Mooney test pilot who worked his way to Engineering VP before changing employers. After leveling off, I used to pull back the throttle enough to make the MP needle move, then set RPM, hoping to create turbulence in the carb throat and get better atomization. Never saw much effect, and couldn't run LOP anyway.

I've been advised that WOT will reduce my range ~40 nm, or 5%. Got a longer trip coming up, we'll see about speed and fuel burn.
 
Hank S said:
This works great for me, and many others that I know.

Retarding throttle during climb increases your engine temps because you slow down (less fuel AND less airflow through the cowl), plus you climb slower so you're exposed to this bad situation for a longer time.

WOT & Full RPM from the end of the runway to cruise altitude. If high enough (~7000'), only pull back RPM. Push for 500 fpm to descend, and trim away yoke force. Level off and reduce throttle to reach flap speed. Fly a normal pattern and land with throttle at idle.

I'm a recent convert to WOT operation, after talking with a former Mooney test pilot who worked his way to Engineering VP before changing employers. After leveling off, I used to pull back the throttle enough to make the MP needle move, then set RPM, hoping to create turbulence in the carb throat and get better atomization. Never saw much effect, and couldn't run LOP anyway.

I've been advised that WOT will reduce my range ~40 nm, or 5%. Got a longer trip coming up, we'll see about speed and fuel burn.
Click to expand...

I think you misread that. I meant passing through 500 ft. in the climb :lol:
 
When you decrease engine power by reducing rpm the manifold pressure goes up
When you decrease engine power by leaning the manifold pressure stays the same.
When you decrease engine power by throttle the manifold pressure goes down.
When you decrease engine power by leaning the rpms drop slightly, then go back up (though not all the way to where they were)
 
Last edited:
Fearless Tower said:
A lot of warbird operators use reduced power settings for takeoff these days, but even that has started more than a few internet fights.
Click to expand...


That has more to do with lack of higher octane 130/115 gas than anything. B-25s R-2600s are derated from 44" to 39.5" with 100LL. We always reduced power soon after getting gear and flaps cleaned up to climb power.


Jim R
Collierville, TN

N7155H--1946 Piper J-3 Cub
N3368K--1946 Globe GC-1B Swift
N4WJ--1994 Van's RV-4
 
Cpt_Kirk said:
Have you seen the MX records or are you saying that because no one has augured in due to an engine failure? The HP/Complex endorsements are being given out like candy and are doing general aviation a disservice.

Learn how to properly operate an engine. You owe it to your passengers.
Click to expand...

Yes, I see the mx records on a daily basis, I'm a mechanic for the school aswell as flying, all of our engines make TBO and are in very good condition when we take them off the wing. I am all too aware how to "properly" operate an engine, just sharing my experiences vs other peoples.
 
Hank S said:
This works great for me, and many others that I know.

Retarding throttle during climb increases your engine temps because you slow down (less fuel AND less airflow through the cowl), plus you climb slower so you're exposed to this bad situation for a longer time.

WOT & Full RPM from the end of the runway to cruise altitude. If high enough (~7000'), only pull back RPM. Push for 500 fpm to descend, and trim away yoke force. Level off and reduce throttle to reach flap speed. Fly a normal pattern and land with throttle at idle.

I'm a recent convert to WOT operation, after talking with a former Mooney test pilot who worked his way to Engineering VP before changing employers. After leveling off, I used to pull back the throttle enough to make the MP needle move, then set RPM, hoping to create turbulence in the carb throat and get better atomization. Never saw much effect, and couldn't run LOP anyway.

I've been advised that WOT will reduce my range ~40 nm, or 5%. Got a longer trip coming up, we'll see about speed and fuel burn.
Click to expand...

You may want to take a look at the MAPA test pilot articles. The articles discuss WOT operations regarding the induction system inefficiencies, which are prior to the J model. Not sure what model you have. But the cliff notes is that J and beyond should be run WOT.
 
You must log in or register to reply here.
Back
Top