First flight after overhaul

[Marahute]

Going up in my newly overhauled J / Lycoming, combined with annual. Reading lots of conflicting suggestions, 1 hour 75%, only 30 minutes 75%, no touch-and-gos.  I was planning on 30-45 minutes at 75%, one, maybe two (full stop)landings, then my flight home, which should be about 90 minutes. Appreciate any kernels of wisdom!

[shawnd]

Probably a good reference for you would be the factory bulletin on the topic :

Service Instruction No. 1427 C

Lycoming Reciprocating Engine Break-In and Oil Consumption

https://www.lycoming.com/content/service-instruction-no-1427c

 

[toto]

In addition to following the Lycoming guidance, one piece of advice is to remove the cowling and do a very careful inspection of the engine as part of your preflight. You never know what you might find.

I once discovered after an engine overhaul and my first test flight that half of the spark plug leads were only finger tight. If I had pulled the cowl before the preflight, I would have caught this before turning the key. 

There are all sorts of stories about people finding rags or wrenches or disconnected hoses after an overhaul. Get a bright flashlight and examine the engine like your life depends on it. 

[shawnd]

42 minutes ago, toto said:

There are all sorts of stories about people finding rags or wrenches or disconnected hoses after an overhaul. Get a bright flashlight and examine the engine like your life depends on it. 

..  cause it does!

[Hank]

5 hours ago, toto said:

There are all sorts of stories about people finding rags or wrenches or disconnected hoses after an overhaul.

I've found tools on my car engine several times, days after much simpler jobs were done.

[Fly Boomer]

46 minutes ago, Hank said:

I've found tools on my car engine several times, days after much simpler jobs were done.

Whose tools?  

[anthonydesmet]

9 hours ago, Marahute said:

then my flight home, which should be about 90 minutes

When I broke mine in, I did my first two flights (about 120 min total) within 50 miles of home plate and all landings at home plate to full stop and shutdown. You also want to minimize prolonged ground time (I.e taxi to takeoffs). Full stop, back taxi to takeoff multiple times is probably not what you want to be doing first 30 to 50 or so hours. The most important thing is to fly the engine.

[skykrawler]

Some overhaul facilities will run the engine for 2+ hours on a test stand.  You should look at the engine log book to see if that was done...in which case certain steps in the Lycoming bulletin have already been accomplished.

 

[Paul Thomas]

For break in, follow the Lycoming or engine builders recommendation; some builders do some of the break-in on a stand for you so they'll have modified instructions.

[GeeBee]

Follow the factory bulletin and fly a race track overhead your departure field for the first 5 hours staying within gliding distance.

[TheAv8r]

13 hours ago, shawnd said:

Probably a good reference for you would be the factory bulletin on the topic :

Service Instruction No. 1427 C

Lycoming Reciprocating Engine Break-In and Oil Consumption

https://www.lycoming.com/content/service-instruction-no-1427c

 

^ Follow this plus your engine shop's break-in instructions. Most of the time their warranties are built on those instructions, if you don't follow them, they may not warranty your engine because of how critical the break-in period is. 

On my M20E, my break-in flight was 1hr flight time, we circled over the airport at 3000ft for an hour, did our best to minimize ground time (towered field so some of it is what it is) and then tookoff at full power, left it full up to 3000 monitoring CHTs, let it run full for a bit then pulled it back to 80% power or so and let it run there for an hour. After an hour, we gently took it down, keeping the power in, only going to idle when we were in the flare over the runway. 

[toto]

I’m pretty far from an expert on this, but I’ve done a number of break in flights. My understanding is that most of an engine’s lifetime wear happens in the first 20 minutes of flight, and that 90% of the break-in wear happens in the first hour. Stabilized oil consumption is the key indicator that the engine break-in wear has ended, but a drop in CHT for each cylinder would happen normally within the first 10 hours or so. 

When I have done these flights, it’s one hour circling the field at about 3000agl, followed by a careful look at the engine to be sure that there are no unexpected leaks. I want to keep this to a hour, because it’s long enough to have most of the break-in wear completed, but not so long that a significant oil leak goes unnoticed. Then the next 10 hours are local flights at relatively low altitude to allow 75% power.

This document from CAP does a pretty nice job covering the key operational points.

https://www.gocivilairpatrol.com/media/cms/Engine_Breakin_draft_v2_dd8a43092bd9f.pdf

 

[M20F]

1 hour ago, TheAv8r said:

 your engine shop's break-in instructions.

This the only answer.  You paid them $40-120K, if you don’t trust their instructions why trust them to rebuild?