The Flying Borescope

The heart of the Cobra system is a solid-state charge-coupled device (CCD) in the tip of the probe. This enables sufficient lighting in an alternative of arrays to offer either monochrome or colour video images as required. The image signal is then processed for digital transmission to the TV screen or even a video recorder if a copy is required. Other valuable attributes of the Cobra is its ability to zoom in on an area of interest, magnification, image enhancement and even image recognition.

The video picture is also much clearer on a video borescope in comparison with the previous generation of commonly used fibrescopes. On a fibrescope the image is composed of honeycomb like patterns that leave grey areas throughout the picture which consequently results in an overall fuzziness. Additionally, the video unit allows a number of people to view the area under observation whereas the fibrescope is restricted to a single operator who inevitably is prone to eye fatigue and possibly error judgement.

The other great asset of this system is its manoeuvrability within confined spaces. As the probe is barely 6mm thick, it can enter areas previously difficult to monitor. Additionally, the unique air jet system allows the lens to float rather than being tugged or pushed through confined areas. Thus in addition to better resolution, the unit suffers much less damage than its rivals which in turn means less maintenance costs and greater systems-up time. Generally, experience indicates that fibrescopes are sufficiently seriously damaged after only five to eight inspections to warrant repair or replacement. The low incidence of damage to video units in the three years they have been available suggests considerable long-term time and financial saving for every maintenance shop.

How does the Cobra work in the field? Panametrics cites the 1986 instance where Aviall received a phone call from a regional US carrier who was concerned about a potential problem. Their analysis of the problem had led them to the conclusion that an internal engine inspection was required: Unfortunately that meant that the engine would have to be removed from the aircraft causing severe economic loss for the small carrier. Fortunately Aviall had just purchased a Cobra RPB-201O and after receiving the call for help dispatched an engineer to the suspect aircraft for an on the spot inspection.

Using the Cobra with its jet-assisted probe, Aviall was able to complete the inspection in less than two hours while the engine remained on the aircraft. The concern over the potential problem was alleviated and the aircraft was back in service in record time. The cost saving to Aviall’s client was to say the least considerable.

Locally, Panametrics claim through US experience, that the inspection of P&W JT8D combustion liners takes a mere two hours with the Cobra as against eight or nine using previous techniques. In the Tullamarine engine shops late at night that capability can mean the difference between getting that 727 on line for the first flight of the morning or having to reschedule half your fleet to accommodate the missing aircraft.

Obviously the Cobra system will generate great interest within the engineering shops of Ansett, Australia and Qantas in addition to our bigger GA facilities and Services.