· Time period between applications, and personnel who will perform dilution will
be as directed
by the local commander. When time between applications is less
than 25 hours, procedures
outlined in steps (b) and (c) will be accomplished.
· When time period between applications exceeds 25 hours and is less than 65
outlined in steps (b) through (e) shall be accomplished.
· Engines which have over 130 hours of operation since new, or newly overhauled,
or have over
65 hours of operation without being diluted (dirty engines), may be
periodically diluted after
following all procedures outlined in steps
Do not allow oil pressure to fall below 15 psi indicated during dilution operation.
Extreme caution must be exercised to prevent overdilution.
Dilute oil 10 percent, using dilution procedure outlined in applicable operator's
When amount of dilution is not expressed in terms of percent in the applicable operator's manual,
a comparable dilution time shall be specified. The dilution time is based on an ambient
temperature of 10 °F (-12 °C), and is usually presented in a dilution table.
Upon completion of steps (a) and (b), and prior to takeoff or high power operation,
operate engine a minimum of 10 minutes to an oil temperature above 122
F (50 °C).
On aircraft incorporating a diverter-segregator oil system, care should be taken to
ensure that main oil tank and hopper are filled in accordance with instructions contained in applicable
aircraft maintenance manuals.
The following additional procedures will be adhered to on engines which are
periodically diluted at intervals greater than 25 hours:
On engines equipped with automatic engine controls, desludge by advancing throttle
to 2000 rpm and then cycle propeller through three cycles.
On engines equipped with propellers using engine oil, cycle propeller through three
Operate supercharger through three cycles, if equipped.
During above operations, oil temperatures should be maintained below 122
°C) as long as possible. Before entire operation is completed, oil temperature may exceed 122 °F (50 °C).
Operation should be for approximately 10 minutes, but may exceed this, when
necessary, to accomplish entire procedure.
Upon completion of preceding operations, remove, inspect, and clean when
applicable, engine inlet oil screen, front and rear sump plugs, rocker box drain mainfold strainer assembly,
and automatic engine control screen.
If excessive deposits are noted during screen examination, engine should be run an
additional 10 minutes, and inspection requirements contained in step 6 repeated.
After shutdown (preferably 1 to 2 hours), drain 1 gallon of oil from Y drain, hopper
tank, and oil cooler drain to eliminate sludge which may have accumulated at these points.
Reservice oil tank hopper to full normal level on engines using diverter-segregator
Engines which have over 130 hours of operations since new, or newly overhauled,
and have over a 65-hour period of operation since last dilution (dirty engines), require that the following
procedures be accomplished in addition to those outlined in steps (b) through (e) above.
In place of oil draining required by procedures outlined in step (e) 8, drain
and replace all oil from engine oil tank.