Engine Break In Landing

[Manchu16]

I have read in many of the break in processes that you should avoid long cruise descents at lower MPs. What is the best way to get a FP bird back on the ground?

I am guessing, slowly retard RPM at a constant altitude. Will reduce CHT with out shock cooling and will slowly drop MP as the RPMs and speed drops. Once slow enough, start to drop and fly a continuous descent to landing. It sounds like the intent is when at higher RPM (65%+ you want the MP up there as well to keep the ring seated). no high power dives that would unload the prop/engine at high RPMs.

Do I have that correct? Or is there a better way.

 

[Bevan]

Fly with wheel pants off for more drag.

B

 

[PCHunt]

You can do a 2 or 3G turn at mid power, and that will help you descend.

 

[PhatRV]

I have read in many of the break in processes that you should avoid long cruise descents at lower MPs. What is the best way to get a FP bird back on the ground?

I am guessing, slowly retard RPM at a constant altitude. Will reduce CHT with out shock cooling and will slowly drop MP as the RPMs and speed drops. Once slow enough, start to drop and fly a continuous descent to landing. It sounds like the intent is when at higher RPM (65%+ you want the MP up there as well to keep the ring seated). no high power dives that would unload the prop/engine at high RPMs.

Do I have that correct? Or is there a better way.

I have 5 hours of engine break-in in my phase 1 flight testing. All the flights so far had been at around 4500MSL which was high enough for safety but low enough to keep the high manifold pressure for engine breaking. The throttle was max at climb but kept at 75-80% for cruise in order not to overspeed the prop. I found the time to descend for landing was very short, less than 5 minutes, compare to about 1 hour of flying (pattern altitude is 1500MSL). The throttle was retarded to near idle at descend to pattern altitude with my propeller configuration. From pattern altitude to landing was almost full idle in order to slow down with some throttle control on final to maintain speed and glide slope. I noticed the drop in CHT was at around 4hr mark. There were stretches after 3 hours that I was doing stalls with engine at idle but they didn't affect the break-in. Other with the same IO360M1B engine said his break-in was done at around 4 hour mark as well.

Edit: most people at the field performed their engine break-in at 2500MSL but the test pilot thought it was too low for comfort. But by flying at a lower altitude, you don't have to spend that much time descending.

 

[Scott Hersha]

You can do a 2 or 3G turn at mid power, and that will help you descend.

As an EAA Flight Advisor, I don’t recommend making 3G turns on your first flight or during engine break in on your first flights. Those G limit flight envelope procedures come later during phase 1. Breaking in a new, or newly overhauled engine should be done with as high manifold pressure as you can maintain, without exceeding CHT maximums that you have evaluated for your first flight (consult with your local flight advisor, or Lycoming for this). Maintaining a higher MP usually means staying at a relatively low altitude, but safely high enough to allow a power out landing at the airport of departure. Of course this means staying right over the airport for your first one hour flight, or maybe more (@ 500-1000’ above pattern altitude).
With a fixed pitch prop you should plan your landing pattern to allow using some power during the approach to landing. May require a 2-3 mile final, but the goal is to allow more gradual CHT cooling. Whether you have a FP or CS prop, your engine will be at idle when you land, so gradual power reduction should result in more gradual, less stressful loads on your new engine. Of course, your first engine run should be of long enough duration to allow engine temperatures to stabilize, even though they will be a little high, and then held there for, preferably, an hour - or more. If you approach any of your pre-planned limits on CHT/oil temp - land right away.

 

[rv8ch]

Your idle might not be set right, so you might have either more power than you want during the landing/rollout, or your engine might quit during rollout. Not a big deal, but just be aware.

 

[PCHunt]

I stand corrected....

As an EAA Flight Advisor, I don’t recommend making 3G turns on your first flight or during engine break in on your first flights. Those G limit flight envelope procedures come later during phase 1. ...<SNIP>...

Of course you are correct. I was only thinking of how to maintain power and descend, and didn't consider the first flight aspect.

Thanks for the correction.