Rotary Wing Break-In

Break-in of helicoper engines is done by following a sequence of steps ranging from engine service of the engine on the ground to progressively increase its power output during operation. Although this Service Instruction contains detailed information about engine break-in, it is impossible to cover all aspects of break-in for individual helicopter models. For that reason, refer to the POH for a particular helicopter model. Also, refer to the applicable Lycoming Operator’s Manual for the engine.

For break-in of piston engines in helicopters:

1. Because helicopters always operate at a fixed or rated engine speed, any decrease of engine RPM necessary during break-in must be done with the helicopter on the ground and with the rotor engaged. During flight, make all power reductions by manifold pressure alone.
2. Some helicopters do not have a red line on the manifold pressure gage and use all rated power. Some gages have a red line for indication of airframer limitations but not engine performance parameters. In the case of Lycoming model HIO-360-D1A, it has graduated manifold pressure values as shown in the Lycoming Operator’s Manual.
3. Because of the difference in helicopter models, refer to the helicopter POH for methods of oepration for a specific helicopter regarding rotor engagement, manifold pressure ratings, the method of rotor engagement, and centrifugal clutch or manualoperated belt drive.

A. Ground Operational Test

1. Refer to the latest revision of Lycoming Service Instruction No. 1014 and make sure the engine has the correct grade and quantitiy of oil.
2. Put the helicopter in a position facing the wind to take advantage of prevailing wind to keep the engine cool.
3. Make sure the throttle and mixture control, if applicable, are at the FULL-OFF position.
4. Refer to the helicopter POH for the correct start-up procedures. Start the engine and operate the engine for 5 mintues at idle RPM (1200-1450 RPM)
5. Adjust the idle mixture (if applicable) and oil pressure as necessary
6.  Do a magneto check, if applicable, per the POH
7. Stop the engine
8. Examine the engine for oil and fuel leaks
9. Start the engine and operate for 5 minutes at idle speed (1200- 1450 RPM)
10. Engage the rotor, if necessary, and increase the engine RPM to 50% to 60% of rated engine speed for 5 minutes with rotor blades at flat pitch (collective full down).
11. If the oil pressure is at the correct operating pressure and the oil temperature is between 180˚F and 200˚F (82˚C and 93˚C), with the cylinder head temperatures between 350˚F and 400˚F (177˚C and 204˚C), increase the engine RPM to 80% of rated engine speed for 5 minutes, followed by 100% airframe manufacturer’s rated engine speed for another 5 minutes.
12. After operating the engine for the last 5-minute segment, let the engine cool as recommended in the POH and then stop the engine.
13. Drain the oil from the engine and change the oil. Refer to the latest revision of Service Instruction No. 1014.
14. Remove and clean the suction screen in the oil sump.
15. Clean the oil pressure screen and/or replace the oil filter.
16. Make all necessary oil pressure adjustments.
17. Install the suction screen and oil pressure screen (or new oil filter); torque per the Table of Limits.
18. Add the correct grade and quantity of oil. (Refer to the latest revision of Service Instruction No. 1014).
19. Start the engine and let it operate at 1450 RPM idle.
20. Engage the rotor, if necessary, and increase the engine speed to 2000 RPM.
21. Warm the engine to do a ground operational check as described in the helicopter’s POH.

NOTE – If sufficient oil pressure indication is not seen within 30 seconds, stop the engine, identify and correct the cause.

NOTE – For correct break-in, do not let the cylinder head temperature go to above 420˚F (216˚C).

B. Flight Test

1. Start the engine and operate it at 1450 RPM
2. Engage the rotor, if necessary, and increase the engine speed to 75% RPM
3. With the engine warm, do a ground operational test in accordance with the helicopter manufacturer’s POH, including a magneto check
4. Put the helicopter into a hover mode for 10 minutes while monitoring the manifold pressure, fuel pressure, oil temperature, oil pressure and cylinder head temperature, etc.
5. If engine instruments are satisfactory, go to cruise altitude
6. Operate at cruise power at 70% to 75% of rated power for 30 minutes to keep a constant safe altitude.
7. At the end of the 30-minute flight at 70% to 75% power, record the manifold pressure and engine temperature.
8. Increase engine RPM and manifold pressure to maximum specified limits in the helicopter manufacturer’s POH. Hold this power setting for 45 mintues at a constant safe altitude.
9. At the end of 45 minutes, again record the manifold pressure and engine temperature.
10. After the flight test, and before engine shutdown, operate the aircraft either in a hover mode for 10 minutes for the time recommended in the helicopter POH.
11. Record the manifold pressure and engine temperatures.
12. After landing, refer to the POH for cool-down and shutdown procedures.
13. Examine the engine for oil and fuel leaks. Identify and correct the cause of any leaks.
14. Calculate the fuel and oil consumption.
15. If the calculated consumption values are above the specified limits, identify and correct the cause(s). Do the flight test again before releasing the aircraft for service.
16. Remove the oil suction screen and pressure screen (or oil filter). Examine for contamination. Remove contamination. If contamination is found, identfiy and correct the cause of the contamination.
17. Clean the screen and, if necessary, replace the oil filter.
18. Install the suction screen and oil pressure screen (or new oil filter); torque per the Table of Limits.
19. Add the correct grade and quantity of oil. (Refer to the latest revision of Service Instruction No. 1014.)
20. After the helicopter has been released for service, operate the engine on mineral oil until oil consumption is stable. (Refer to the latest revision of Service Instruction No. 1014.) During this time, keep the engine power above 65% and monitor. Make sure that all aircraft and engine operating temperatures and pressures are kept within limits.

NOTE – Use two crew members to control and monitor the engine instruments, including the aircraft and engine operating temperatures and pressures. If any parameters are out of tolerance with the helicopter PH or engine and aircraft operating manual limitations, stop the break-in procedure. Identify and correct the problem. Do any necessary maintenance. Then continue with the break-in procedure.