Increasingly aircraft are electrically powered with many doing away with vacuum systems for instrumentation entirely. This makes it all the more important to have an efficient and reliable electrical system, and this requires regular maintenance. After a number of years use, resistance in the circuits builds up, particularly from mismatched or incompatible metal components. The result of these is often a bad earth and thus a failure of the circuit.

In addition, the electrical system may be a source of fire, particularly the huge risk of inflight cockpit fires, as described by Jim Davis in his column in September 2020. For this reason, it is worth getting your aircraft’s electrical system, and in particular its wiring harnesses, replaced on a regular cycle, such as every 10 years, if reliability is to be assured.

Over time it is inevitable that many of an aircraft’s systems or components are modified and parts replaced, and this usually requires connecting new electrical cables to old. These connections are vulnerable and is another reason why quality maintenance should always be paid for, and the entire system replaced on a regular basis.

Aircraft batteries are a particularly expensive item and it is essential to ensure that lead acid batteries are not fully drained as they seldom fully recover their ability to hold a charge for any useful length of time. Therefore, it is again important to ensure that there are no leaks or minor short circuits within an electrical system.

In addition, all electrical drain sources such as courtesy lights should be regularly checked for the correct operation of their switches. There can be nothing worse than setting out on an important flight with minimal time to spare and then finding that the battery is completely discharged.

Another key reliability requirement for electrical systems is for night flying. It is essential that small items that do not get regularly used or checked, such as instrument lighting rheostats, are in good working order.