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Engine break in vs Phase One fly off

Snoho3

Well Known Member
Wondering how folks approach flying off their phase one hours using test cards vs. properly breaking in a new engine. The cards I plan to use have various slow flight/low power exercises, plus I have a definite need to do many laps around the pattern in this new airplane, obviously much of which will be at reduced throttle. Thats’s all at odds with recommended break in procedures. How do people reconcile the two?

If I do the two sequentially I am looking at many more hours than 40 before the airplane and I are properly introduced to each other... thanks for any thoughts.
 
Wondering how folks approach flying off their phase one hours using test cards vs. properly breaking in a new engine. The cards I plan to use have various slow flight/low power exercises, plus I have a definite need to do many laps around the pattern in this new airplane, obviously much of which will be at reduced throttle. Thats’s all at odds with recommended break in procedures. How do people reconcile the two?

If I do the two sequentially I am looking at many more hours than 40 before the airplane and I are properly introduced to each other... thanks for any thoughts.
You need to focus on breaking in the engine until that's done, or you will end up having to hone your cylinders. Besides the first flight where you simply make sure all is ok, and you can land safely, run the engine as hard as you can. This is what I've read, and what I did, and seems to have worked. Any testing that requires full power is ok. Also, don't climb high, stay as low as is safe to keep the MP as high as possible.
 
Engine breakin

When I finished my first -4 in 1984 I asked the old mechanic at our airport, who also happened to be a WW2 P-47 pilot -how should I break the engine in. He said and I quote-fly it like you stole it. So I did.
 
It all needs done and you can do all of it. People like me that likes LOTS of data typically need more than 40-hours to get it. May take something like 75-hours in my case. After the phase I hours are flown off, I had all the data the FAA wanted me to have but not all the data that I wanted. Yes everything was flown two, three, or more times.

Run the engine as hard as you can early on. Do the low power stuff but follow it up with more high power operation.

No two pilots are the same. You can work all the requirements into Phase I and still get a good engine break in. There will be times when you must do things in Phase I that are not ideal for break in but a good break in can still be obtained as long as you do not have chrome or other plating on your cylinder bores.
 
The answer is that test cards don’t always need to be done sequentially, without repetition, or necessarily in order. Yes, some tests should be done before others, and (for instance) the test plan in the EAA FLight Test Program is a good recommended sequence - but there is nothing that says you cant fly a few hours of engine break-in circling the airport at high power settings after completing card 1 and then going on to card 2. I call these flights things like “1a”, 1b”, 1c” etc in my records.

Look at any test plan as a guide that might have to be modified for your particular situation - not a rote recipe that has to be followed exactly. And Phase 1 takes as long as YOU want it to take (above the minimum hours specified in your Ops Lims of course) to complete your testing. It’s not a “fly off” - it is a test program.

Paul
 
In my 10, I spent the first flight (2 hours) circling the airport at high speed and always within glide distance; shallow climb to keep CHTs in check. I landed fast, as I had not checked stall speed (7K' runway). Second flight, I did stall tests after more circling. a small amount of low power flight won't hurt anything. I then did only testing that could be done at high power for another 10 hours.

The only thing you really need to be cautious about in the first 10-15 hours is avoiding CHTs above 430 and avoiding low MAP decents (ring flutter). I would do stall tests and a bit of slow flight early in the testing, lest you become surprised in early landing events.

Larry
 
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Engine Break In

At the A&P school I attend many years ago we did an STC on an O-320 to increase it from 150 - 160 hp (increased compression ratio); and the break in procedure was to fly it at wide open throttle until there was a drop in oil temp. which was the signal that the rings had fully seated. That's what we did, and it broke in nicely with low oil burn, etc. Another project at the school was a twin Barron, and the owner refused to conduct a first flight until the overhauled engine had ten hours on it for whatever reason. The a/c had been sitting at the school for two years when I saw it, and each new class would run it on the ground at wide open throttle, but since the static rpm wasn't high enough, the cylinders would glaze over, and the next class would pull them off and deglaze them, etc. The bottom line is do what the mfg. suggests, which probably is to run it hard for the first hour, and then start your slow flight time to climb events, etc. after it's been nicely broken in.

Doug
RV-3A renovated and sold
RV-9A / Mazda 13B awaiting completion
 
What I did

My first flight included break in, as I had just built the engine as well as the plane. Because RVs are so well documented, I had all confidence the aircraft would be just fine, and any trim issues would be negligent. My focus was the basic engine parameters and following break in procedure. I briefed my ground "watchers" I would be in the air over the field for a bit over an hour. I didnt worry about slow flight checks to validate stall vs airspeed indication until the very end of the flight. After an hour of full to varying high power settings, I did a couple slow downs to stall and then landed. Almost 1.5 on the Hobbs on first flight.
 
The last of the EAA Homebuilder's Week webinars, still available on the EAA site, was Mike Busch talking about engine break in. He also addresses break in vs first flight. Well worth an hour and a quarter of your time.
 
My first flight included break in, as I had just built the engine as well as the plane. Because RVs are so well documented, I had all confidence the aircraft would be just fine, and any trim issues would be negligent. My focus was the basic engine parameters and following break in procedure. I briefed my ground "watchers" I would be in the air over the field for a bit over an hour. I didnt worry about slow flight checks to validate stall vs airspeed indication until the very end of the flight. After an hour of full to varying high power settings, I did a couple slow downs to stall and then landed. Almost 1.5 on the Hobbs on first flight.



This is my exact thinking as well.
I'll be test flying as soon as the wx permits, AND breaking in a new engine at the same time.
 
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