DESCRIPTION

TECHNICAL FIELD

This invention describes method of identifying and indicating drip loop length of loom to be left unsecured while routing looms on aircraft to avoid short or excess of loom length for connecting to its mating LRU after its installation.

BACKGROUND OF INVENTION

An aircraft houses number of Electrical, Avionics and Mechanical LRUs. These LRUs are scattered on aircraft at different locations and are interconnected with electrical cable harness. A fly-by-wire aircraft consist looms of qty around 400 numbers which involves electrical connectors of quantity more than 1000 numbers. A cable harness, also known as a wire harness, cable assembly, wiring assembly or wiring loom is an assembly of cables or wires which transmit signal or electrical power. While routing and securing of harness on the aircraft, a sufficient length of harness is to be left unsecured (drip loop) length at the connection ends for mating to LRU.

A drip loop is a short section of the harness immediately before the connection point. As a best practice, the drip length is designated to prevent fluid ingress into the connector. Also, the use of drip loops provides additional slack on the harness limiting the stress on connectors

As per the aircraft building process, electrical looms need to be routed on the aircraft before their mating LRUs are installed on aircraft: Hence, drip loop length of the loom on the aircraft for mating to the LRU is to be known or defined to start looms routing.

With the present practice of leaving approximate length (undefined) of harness may end up in short or excess in length of loom. Shorter length results in removal of entire looms and re routing with leaving sufficient length. Whereas, excess length, results in looping of the looms which is not acceptable on aircrafts as per the applicable standards.

Hence there is a need to define drip loop length of the loom before routing on aircraft. Cleat is a small metallic or plastic member used to secure the harness which is fastened to aircraft structure at regular intervals along the length of the harness (refer Fig-1).

SUMMARY OF INVENTION

This invention describes the technique of defining drip loop length looms in aircraft engineering drawings without resulting in any short or excess in length of loom.

PROCESS DETAIL DESCRIPTION

L Measure drip loop length of loom at the ends from the nearest loom securing point (i.e., cleat) on existing aircraft,

ii. Identify the above cleat with unique identification number in the engineering drawing,

iii. Indicate the above measured length drip loop in their respective engineering drawing (i.e., loom routing drawing),

iv. Unlike other cleats, the above identified cleats are to be installed necessarily at the drawing called locations and are to be identified with its ID on the aircraft,

v. Once the above said engineering drawings are available, Cleats will be installed on the structure as per the drawing,

vi. Looms will be routed on aircraft leaving defined drip loop length at the ends indicated in the drawing (refer Fig-2).

vii. Looms are mated to the LRUs after their installation on the aircraft without any problem of short or excess in length of the loom (refer Fig-3).

CLAIMS

We claim the methodology of indicating drip loop length with respect to a defined aircraft structure member in engineering drawing of aircraft electrical looms.