In an age of ultramodern technology for flight control and navigation in civilian and military aviation (satellite navigation, fly-by-wire etc.), ensuring flight safety enjoys top priority − even where adverse external influences prevail. Electrical systems have to function reliably and error-free regardless of any and all internal and external influences.
Airborne hazards can quickly result in disaster. The demand for uncompromising safety applies as well under severe weather conditions: extreme cold, snow, hail and thunderstorms. In particular the latter is a major challenge for on-board electrical and electronic systems (avionics), although aircraft are equipped with a fully conductive outer skin that functions like a Faraday cage – which means that in principle adequate protection against being struck by lightning is provided.
Day after day, airplanes are exposed to all conceivable ambient influences such as electromagnetic fields (radar, radio/ television, cosmic radiation), bird strike, storms, hail, wetness, extreme pressure and temperature differences as well as lightning.
Danger due to Lightning
Static charges can also cause interference in aircraft radio equipment. In order to prevent this, aircraft are furnished with so-called wicks. These provide the excess electrons with a means of flowing back into the atmosphere instead of being retained within the airframe. Static charging is avoided in this way. The ends of the wicks look like brushes and offer only minimal resistance, making it easier for the electrons to escape.
The so-called KELVIN measuring method is implemented in measuring instruments for bonding and wick tests, i.e. a 4-wire measuring method (voltage-correct measuring method). All contact and measurement cable resistances are compensated for by this measuring method, because these would otherwise distort the final measured values. Point-to-point, point-to-structure or reverse current measurement is used.
Milliohmmeters powered by large batteries, which are thus unwieldy and relatively heavy, were commonly used in the past for the bonding test. These instruments were also considerably more expensive due to higher levels of mechanical complexity. They offer test currents of 1 or 10 A (power pulse current!), whereas our instrument only delivers 0.2 or 1 A (pulsed) DC test current, but this is more than adequate for most applications.
The METRAHIT series of multimeters provides users with extremely lightweight, compact and rugged, battery powered, highly precise measuring and test instruments. These features are a significant advantage for on-site use. Beyond this, the comparatively low purchase price offers a convincing economic advantage.
Renowned aircraft manufacturers have been using the METRAHIT 27EX for years in order to detect contact junctions in potentially explosive atmospheres (fuel tanks). The METRAHIT 27 has been used over long periods of time in large quantities by specialized service companies, aircraft manufacturers, aircraft yards operated by the airlines, such as, for example, Lockheed Martin (service kit for F16 and F18 fighter jets), Lufthansa’s aircraft yard in Hamburg, a service company in Norway and many others.
The METRAHIT IM XTRA is a further development of the METRAHIT 27. It includes all of the functions of the time-tested METRAHIT 27, as well as useful state-of-the-art enhancements.
Do you have any questions on the product or do you need technical information or details on the current delivery period? Our International Sales will be pleased to assist you.