28-40 Fuel Flow Check
1. Open mast fairing per Section 53-22. Remove engine cowling per Section 53-21.
2. Refer to Figure 28-2. Attach a temporary hose to one of the vent weldment openings. With
the fuel cap installed, blow into the hose (do not use compressed air) and verify air blows
out the other vent opening. If air does not blow out the other vent, remove obstruction(s)
in vent line(s) or in fuel bladder and repeat check.
3. Defuel helicopter per Section 12-42, then service helicopter with 19.4 gallons of fuel per
Section 12-41.
4. Weigh a suitable, empty container having a volume of at least one gallon. Record weight
of empty container in table below.
5. Pull fuel valve OFF and disconnect B283-12 hose assembly from the engine fuel inlet
fitting.
6. Using a second, suitable container, push fuel valve ON and drain fuel into second container
for a few seconds to purge system of air. Then fill the weighed container for 60 seconds.
Weigh and record weight of empty container & 60 seconds of fuel flow in table below.
7. Perform the following calculation:
Combined weight of empty container & 60 seconds fuel flow:
lb
Subtract Weight of empty container:
—
lb
Equals Weight of 60 seconds fuel:
=
lb
8. Minimum fuel flow (at 19.4 gallons of fuel) is 4.75 lb/min (60 seconds). If fuel flow is less
than 4.75 lb/min, remove obstruction(s) in vent line(s), fuel bladder, fuel hoses, fuel valve,
or fuel strainer (inside bladder at outlet), and repeat check until fuel flow is satisfactory.
9. Close mast fairing per Section 53-22. Install engine cowling per Section 53-21.
Page 28.12 Chapter 28 Fuel System R66 Maintenance Manual 25 OCT 2010
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