New engine altitude restrictions

Murdoughnut

Well sized member
Our club's Archer just came back from annual and an engine overhual, and MX is telling us the plane is altitude restricted to 5,000 feet for the first 100-150 hours of engine break-in time. Just curious why that is and if that's SOP. Thanks!
 
From what I recall, 25-50 hrs is normal break-in with no stalls or touch-n-go’s. 10 hr oil changes to get all the metal shaving out. I believe the altitude restriction is for cooling.
 
Take this question to a general aviation site and you'll get all sorts of heavy breathing about 'shock cooling.' It goes in the same bucket of utter • superstition as running over square and getting on-step. However, if Lycoming or the overhaul company are the ones who actually took the time to write it out as a restriction, then a restriction it is.
 
Our club's Archer just came back from annual and an engine overhual, and MX is telling us the plane is altitude restricted to 5,000 feet for the first 100-150 hours of engine break-in time. Just curious why that is and if that's SOP. Thanks!


It's because the break in requires 65 to 75% power continuously.

100 to 150 hours is a bit excessive though, 25 hours is all it should take.
 
It's because the break in requires 65 to 75% power continuously.

100 to 150 hours is a bit excessive though, 25 hours is all it should take.

I thought so too - I'll have to ask around the club and find out what the deal is with the longer time. Thanks!
 
Our club's Archer just came back from annual and an engine overhual, and MX is telling us the plane is altitude restricted to 5,000 feet for the first 100-150 hours of engine break-in time. Just curious why that is and if that's SOP. Thanks!

MX is looking for cooler air to help with controlling CHT during ring seating, but 100-150 hours is a little excessive. When I was doing flight school maintenance, under the guidance of the engine shop - one of the mechanics would fly the aircraft over the field at 65-75% for an hour or two, or until the temperatures settled down. Then the aircraft was dispatched for cross country flights for the next 10-20 hours, and after that released for full abuse.
 
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