400W Series
190-01226-14 Rev. 3
Instructions for Continued Airworthiness Bell 407
Page 12 of 26
2.5 Periodic Maintenance Instructions
The 400W Series units are designed to detect internal failure. A thorough self-test is executed
automatically upon application of power to the units, and built-in test is continuously executed. Detected
errors are indicated on the equipment via failure annunciations.
Maintenance of the components installed by this STC is on condition, except as noted in the following
table.
Table 1 Periodic Maintenance Inspections
Item Interval
Description/Procedure
400W Series
Unit
12 Months
Conduct a visual inspection (look for signs of wear, deterioration,
or damage to wires, backshells, or connectors) of the 400W
Series unit and wiring harnesses to ensure installation integrity:
1. Inspect the unit for security of attachment.
2. Inspect all knobs and buttons for legibility.
3. Inspect condition of wiring, routing and
attachment/clamping.
4. Inspect related antennas for proper sealing and attachment.
5. Inspect integrity of shield terminations.
6. Inspect for signs of corrosion on equipment, racks and it’s
backplates and rack mounting.
400W Series
Mounting Rack
12 Months
Inspect the mounting rack for any signs of excessive wear,
corrosion, or damage. Check mounting rack corners for cracks.
Check integrity of connector plate attachment to the back of
mounting rack. Check the tightness of fasteners attaching
mounting rack to rotorcraft structure and re-torque 12 to 15 in-lbs
if required.
Replace unit mounting rack if any damage has been found.
Avionics
Cooling Fan
12 Months
Conduct a visual inspection (look for signs of wear, deterioration,
or damage to wire harness and connector) of the cooling fan to
ensure installation integrity. Inspect for signs of corrosion on
equipment and mounting brackets.
400W Series
Mounting Rack
Every 2000
flight hours or
ten (10)
years,
whichever is
first
Perform an electrical bonding test:
1. Remove 400W Series unit from mounting rack
2. Measure the resistance between the mounting rack and a
nearby exposed portion of aircraft metallic structure and
verify it is less than 10 milliohms.
In the event of a bonding test failure, remove the rack and verify
that the countersunk areas around the holes that are used to
attach the rack are free of corrosion or other debris. Clean
countersunk areas using an approved solvent per Bell
specification BHT-ELEC-SPM CHP8. Reattach the rack and re-
verify the resistance between the mounting rack and nearby
exposed portion of aircraft metallic structure and ensure that the
resistance is less than or equal to 2.5 milliohms.
Reinstall the 400W Series unit in the mounting rack
Summary of Contents for 400W Series
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