R22 fuse on back of firewall?

[JB77UK]

What is the purpose of the fuse located on the engine side of the firewall on the R22 - low, near gascolator. You can just about see it in this photo - at the top on the right, a vertically mounted clear glass fuse:

Many thanks in advance for any help,

Jay

[hillberg]

I see a diode on a relay-As the relay deenergizes the break down of the magnetic field causes a voltage spike, the deode shunts the spike to the ground side of the coil.
Made to save the fine electrinics from harm.

[hillberg]

If you see a fuse holder with a fuse in it (with no wires) it's a spare for the clutch.

[powerlimited]

The 3 AMP fuse mounted on the vertical firewall is the Battery Relay Bypass Circuit fuse, used to protect the clock and also the Dual Tacho which is hard wired to the battery through the Clutch Switch.

[CYHeli]

Hillberg, the spare fuse that you describe is next to the warning light test switches under the cowl on the right hand side and that one is for the clutch. The 'relay' is actually part of the oil gauges system, the oil pressure sensor.

As Powerlimited says, the fuse pictured is a fuse to protect the by-pass wire that runs the clock and the RPM gauges. The RPM gauges only get power though when the clutch is engaged. The wire is referred to in the POH/RFM on page 7-12, Systems.
To know if the fuse is working or intact, check the clock prior to start. If it is not working, then the fuse is blown.

[hillberg]

Last R-22 I worked on that fuse for the tach/clock was in the instrament pnl. But that was some time ago, when the battery was in the nose & not the left rear, My have things change.

[Arm out the window]

Used for night flying - operates a light to fool the hamster into continuing to run after sundown.

[topendtorque]

by-pass wire that runs the clock

Obviously I need a souped up fuse to give the clock a few more herbs. The blessed minute hand sometimes juuuust about climbs to a quarter to, before falling back to half past. That's how I pass the time now and then, betting with myself how far it will go each time.

[500e]

My bets on the Hamster