2.
New/newly overhauled
Follow the engine manufacturer’s instructions. These instructions are found either in the
manufacturer’s overhaul manuals, service bulletins, or service letters. Following the manufacturer’s
instructions is especially important if the engine has chrome cylinders which require special
run-in procedures.
Also, before running-up the engine, be certain that it has the proper grade oil in the sump.
Some new and newly overhauled engines are shipped with a special preservative oil to prevent
corrosion. Drain this out and reservice the engine with the correct oil before starting.
3. Pre run-in checks:
(1) Before beginning the powerplant tests, inspect the engine and propeller carefully. With cowling
removed, check all fuel and oil line connections. They should be tight. Check the torque on the engine
mount attaching bolts. Be certain that there are no tools, hardware, or rags laying between the cylinders
or under the magnetos.
(2) Check for the proper amount of oil in the oil tank and that the dip stick gives an accurate reading of
the oil quantity.
4. Safety Precautions: Before the first engine run, ensure the aircraft is tied down, brakes on, and
the wheels are chocked. The builder and flight test team should wear ear and eye protection. All flight
test participants should be checked out on fire extinguisher use and operation. During engine runs, do
not allow anyone to stand beside the engine, or inline or close to the propeller. Making minor adjust-
ments to a running engine, such as idle and mixture settings, is a very dangerous procedure and
should be done with great care by experienced individuals.
5. The First Engine Run:
(1) The first start of the engine is always a critical operation. The engine should be pre-oiled in
accordance with the manufacturer’s instructions. After completing the starting engine checklist in the
Pilots Operating Handbook, the first concern is to get an oil pressure reading within the first 10
seconds. If there is no oil pressure reading -- shut down.
(2) There are three common problems that would cause low or fluctuating oil pressure.
(i) Oil pressure gauge or sender not working. This is easily checked with a meter.
6. Record the engine run-in data: During the engine run, monitor temperatures. Record the readings
and adjustments for future reference. If the temperatures are rising close to the red line, reduce power
and stop the test. Some causes of high temperatures include using wrong spark plugs, engine
improperly timed either mechanically and/or electrically; and the carburetor fuel mixture set
excessively lean.
7. After shut-down:
(a) After each engine run, check for fuel and oil leaks, loose connections, and hot spots on
cylinders (burnt paint).
(b) A very small quantity of metal in the screen is not uncommon in a new or newly over-
hauled engine. It is part of the painful process of ‘‘running-in.’’ If subsequent oil screen checks
(2 hours apart) show the engine is ‘‘making metal,’’ this indicates a problem inside the engine and a
tear down inspection is required.
(c) It also is recommended all fuel sumps, filters, and gasolators be checked for debris after each
engine run. Special attention should be given to the fuel system by the builder who constructed
fuel tanks out of composite or fiberglass materials. Composite and fiberglass strands can be very fine,
making visual detection difficult. Frequent cleaning of the fuel filters and screens early in the flight
testing phase will avoid a gradual build up of loose composite fibers.
Appendix 1 NOV 09
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