28-11 Roll-Over Vent Valves
Refer to R66 Illustrated Parts Catalog (IPC) Figure 28-1.
WARNING
R66 roll-over vent valves contain two anodized aluminum balls,
the orientation of which are critical to vent valve function. The
gold hollow ball on top (earlier ball was blue) floats and seals the
vent in the event of inadvertent over-filling or in-flight sloshing.
The red solid ball on the bottom presses the hollow ball against
the vent seat if the aircraft is inverted.
A. Packing (O-Ring) Replacement and Valve Inspection
1. Remove tailcone cowling assembly per § 53-23, as required.
2. Refer to Figure 28-2. Remove D277 clamp(s) or cut and discard safety wire
securing A729 tube to roll-over vent valve and pull tube off valve.
3. Remove G254-2 fitting or G254-6 retainer. Remove and discard MS29512-10
packing (G254-2 fitting only) and A215-015 o-ring.
4. Carefully remove B208-5 and B208-6 balls using a suction cup attached to a
syringe. Inspect condition of balls, valve body, and fitting or retainer. Clean parts
and verify no nicks, scratches, gouges, dents, cracks, or corrosion.
5. Carefully install B208-6 ball (red, solid) on bottom and B208-5 ball (gold or blue,
hollow) on top in valve body using a suction cup attached to a syringe.
6. Install new A215-015 o-ring in groove inside fitting or retainer. Lubricate new
MS29512-10 packing with A257-6 grease and install over G254-2 fitting threads.
7. Install fitting or retainer and special torque per § 20-33.
8. Fit A729 tube onto roll-over vent valve and install D277 clamp(s) or wrap tube with
two turns 0.032-inch diameter lockwire and safety tube to vent valve.
9. Install tailcone cowling assembly per § 53-23, as required.
28-12 Sump Valve
Refer to R66 Illustrated Parts Catalog (IPC) Figure 28-5.
A. Removal
1. Defuel helicopter per § 12-42.
2. Refer to Figure 28-2. Cut and discard safety wire (if installed) securing A729-43
tube to A761-2 or 1250H (sump) valve and remove tube.
3. Remove valve from G154-1 outlet assembly; tape bladder opening.
4. Actuate and lock valve to expose stem; remove and discard o-ring.
Page 28.6 Chapter 28 Fuel System MAY 2015
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