When helping our customers purchase Continental aircraft engines, aircraft cylinders and speaking with those having their engine overhauled, we always return to Continental Manual M-0 for advice. While there are hundreds of break in opinions online and through the many shops in the country, we always stick to factory guidance and refer back to M-0. You should always print off a copy of M-0 (Section 7) before flying your aircraft with a new, rebuilt engine or fresh cylinders.
Continental M-0 Break-In Instruction Summary
First, Continental starts out with a very important note, and that is running your engine on the ground, at high power, can cause cylinder head temperatures and oil temperatures to exceed normal operating limits and can be detremental to cylinders, pistons, valves and rings. Watch this carefully and avoid a lot of ground time!
Continental says the break-in period is roughly 25 hours, common knowledge shows that break in is complete once "oil usage as stabilized." For your first flight:
1. Makes sure that the initial engine run-in has been completed by the mechanic. See Continental M-0 for instructions.
2. Conduct a normal engine start, run-up and take-off according to your POH. But remember, watch those temperatures!
3. Monitor enginer paramters in the climb to ensure you are operating within the appropriate parameters.
4. Once at cruise, maintain level flight cruise at 75% power with a rich of peak mixture for the first hour of operation.
5. For the second and subsequent hours of flight, alternate cruise power settings between 65% and 75% power with a rich of peak (best power) mixture setting.
6. Descend at low cruise power settings. Avoid long descents or descents at cruise power RPM with manifold pressure below 18 inches. If necessary, reduce engine RPM to the lower limit of the specidied operating range to maintain sufficient manifold pressure. Carefully monitor engine instrumentation to maintain levels above the minimum specified CHT and oil temp. Continental recommends keepting the CHT above 300 degrees and wants you to throw out more drag so you can fly at a higher power setting to make this happen.
Notes from our General Manager
Darryl Taylor, our General Manager, has broken in hundreds of Continental engines over the years and has these general rules of thumb:
1. Climb quickly to a safe altitude, while maintaining enough airspeed to keep the CHT's cool. It's a balance.
2. First hour should be maitnained within gliding distance of an hour.
3. Performing a cowling off leak check after the first hour.
4. Work hard to keep CHT's between 300 and 380 degrees!
5. In the break in period, avoid flight training and/or operations that are at low power settings.
Continental has additional Flight Check requirements for it's engines, particularly those equipped with an altitude compensating aircraft fuel pump.