Installation integrity

Six procedures. Almost all of this unit is inspection, and inspection with a number attached wherever one exists.

Procedure 1 — Inspect an avionics installation (S9, S12)

1. Security: mounting tray secure to structure, unit latched into the tray, no movement when pushed.
2. Shock mounts: condition, not perished or collapsed, and bonded (Procedure 3).
3. Cooling: the cooling path clear, ducts connected, fans functional where fitted. An avionics unit starved of cooling fails early and intermittently.
4. Connectors: fully mated, locked, backshells secure, strain relief in place.
5. Wiring: routing, support, separation from power and from fluid lines (AF-K Procedures Procedure 6).
6. Placards and markings present and legible (S1).

Check — push and pull the unit in the tray. Movement means the latch is not engaged, and a unit that moves fails at the connector.

Procedure 2 — Inspect a coaxial installation (S6)

1. Security and support along the run — coax is stiff and unforgiving of unsupported spans.
2. Bend radius — a coax bent tighter than its minimum has changed impedance permanently.
3. Connector condition: center pin present and correct length, no corrosion, backshell secure.
4. Chafe where it passes structure.
5. Separation from power wiring (AF-I Concepts §3).

Check — look at the bend radii. A kinked coax reads as a fault in the system it feeds and nobody looks at the cable.

Procedure 3 — Measure a bond (S10)

1. De-energize.
2. Clean the measurement points to bare metal — you are measuring the bond, not the paint.
3. Measure with a low-resistance method across the bond.
4. Compare against the manufacturer's limit in milliohms.
5. If out of limits: disassemble, clean both faces to bare metal, reassemble, re-measure, restore corrosion protection around the joint.

Check — record the number. "Bond checked" is not a result; a measured value against a stated limit is (AF-I Concepts §2).

Procedure 4 — Inspect static discharge wicks (S11)

1. Count them against the drawing. Missing wicks are common and are a finding.
2. Security — each firmly attached, base intact.
3. Condition — not broken, burned back or eroded beyond limits.
4. Measure resistance from wick to structure against the limit.

Check — measure, and count. A full set of secure wicks with one high-resistance base is an airframe with a preferred discharge path through something else.

Procedure 5 — Test an ELT (S7, S8, R1)

Read the manufacturer's procedure and the regulator's rules first, every time.

1. Test only in the permitted window and for the permitted duration (AF-I Concepts §4).
2. Notify anyone who needs to know before transmitting.
3. Check operation per the procedure, and confirm the signal is received on the monitor.
4. Stop within the permitted sweeps.
5. Check the battery expiry date and the placard, and confirm both against the record.
6. Check the mounting and the antenna connection — an ELT that works and is not connected to its antenna is not an ELT.
7. Record the test.

Check — state the window and the sweep limit before you transmit. A test outside them launches a real response.

Procedure 6 — Inspect an antenna installation (S4, S13)

1. Security — fasteners tight, correct type, no movement.
2. Sealing — no water ingress path. Sealant intact around the base.
3. Corrosion at the interface, which is a dissimilar-metal joint (GEN-G Concepts §3).
4. Bonding to structure (Procedure 3).
5. Condition — no cracks, erosion, or damage to the radome or element.
6. Doubler and structure beneath, where accessible.

Check — look for corrosion staining at the base. It is the visible sign of a failed seal, and the damage is under the antenna where you cannot see it.

The checks, collected

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