Failures in electronic and electrical equipment can lead to expensive claims. The suspect parts may not be costly in themselves but the consequences of the failure may be very serious such as fires. Methodical examination of the evidence, application of appropriate analytical techniques and test, and expert interpretation can be used to determine the cause of failure, responsibility and quantify costs.

The RFA group at Cobham Technical Services has wide experience over many years successfully analysing thousands of different failures arising from many industries; consumer electronics, industrial control systems, rail, automotive, aviation, petrochemical, the built environment and more. With staff experienced in a wide range of fields, techniques and industries, we can bring the right set of skills to bear on any particular situation to impartially and objectively assess the evidence and determine the cause of problems. The cost of this analysis can be very low compared to the cost of the damage.

The range of cases we examine is very broad from low cost domestic equipment failures where personal injury, including hospitalisation, or property damage may be the issue through to failures in critical components in industrial equipment which can cause massive damage and expensive delays – for example in oil rigs or continuously running production machinery.

The investigators tool box

A range of techniques and approaches may be deployed depending on the circumstances including:

• Determination and mapping of the peak temperatures reached by various parts
• Examination of the pattern of hot air flow
• Analysis of soot, smoke and contamination
• Failure analysis of electronic parts and comparison with good parts
• Examination of worn or broken parts
• Examination of features external to the failures to provide additional evidence.

In some cases it is possible to reproduce or simulate the event by creating an initial fault or deliberate damage. The judgement of the cause of the failure will be aided by knowledge at Cobham Technical Services of the construction and potential weaknesses of electronic systems.

Fire damage – buildings and aircraft

We have investigated fires in building which have burnt down. In one case the fault was located to a capacitor and some high voltage parts with inadequate internal joints. There have been several cases where poor design has caused serious fires but the cause could be determined by examination of the seriously burned printed circuit boards. Small fires in passenger aircraft have occurred due to poor maintenance (failure spot wear, contamination etc.), inadequate design and assembly in a piece of electronics. The latter case serves to illustrate how uncovering the underlying cause can involve detailed and painstaking work.

Figure 1. X-ray image of the pairs of fused bond wires on three terminals of the failed IC. The gaps in the wires show where they have fused

Figure 2. The bond wires to the same terminals on the good IC

Faulty equipment

A piece of equipment was delivered as new but never worked correctly at the customer’s premises. On examination at Cobham Technical Services it was clearly found to be not new but had been used and left in a poor state. The most striking evidence was the state of two lenses whose surfaces are shown in figures 3 and 4. These lenses were damaged by the laser in the equipment clearly indicating that the system had seen significant use.

Figure 3. Laser damage to the outer face of the outer lens

Figure 4. Laser damage to the outer face of the inner lens

Presenting the evidence and responding to client requests

Where circumstances are in dispute the clear presentation of evidence is crucial. If the case does go to court, a specific style and layout of report will be required. We are familiar with this aspect and with ensuring that the report is readily understandable by non-technical people.