When it comes to caring for electrical and electronic systems on modern aircraft, specialist help is needed, reports Bernie Baldwin. 

Calling someone ‘an expert’ these days is often meant pejoratively, denigrating someone who has worked and studied their subject for years, achieving notable qualifications and peer recognition. It has been known for generalists to suggest that “people have had enough of experts”.

In aviation, thankfully, the maxim that ‘safety is no accident’ prevails in both of the ways it can be read. So, when it comes to designing and maintaining aircraft, it is clearly the best option to call upon well-trained specialists to do the job. Given the many components, systems and modules making up an aircraft, there are many areas of specialisation, electrical and electronic systems being one example.

In this case, being so specialised often results in the MRO of such systems being entrusted to the original equipment manufacturers (OEMs) – companies such as GE Aviation, Liebherr, Safran, Collins Aerospace, Teledyne Controls and Thales. However, there are also a number of independent MRO companies, such as HEICO and Lufthansa Systems, which have developed strong reputations for their support of this equipment.

Thales is involved in both electrical systems and electronic systems. The company describes electrical technology as “an enabling technology to improve, simplify, automate and control power systems on board aircraft”. It claims a place among the top three players for electrical equipment and systems for aerospace, for which it designs, develops, manufactures and supports electrical power generation and power conversion equipment. 

“Significant strengths are the rare expertise in high power electrical generators and converters associated to strong capabilities in real time control present in the Thales portfolio,” the company declares. Those powering generating and converting systems supply units such as lights (including those for position, anticollision, landing, taxi and the cabin interior), radio equipment, fuel gauges and pumps, plus a range of other equipment.

On the electronics side, Thales Avionics provides flight deck systems, flight management systems, flight controls and other avionics displays and platforms. Whether dealing with electrical or electronic systems (flight control systems, communications/datalink and so on), there are key points to which attention is paid when one of these pieces of equipment needs to be serviced. “When equipment comes in for maintenance, we first check if it is at the latest standard and we test the equipment in order to determine the failure cause,” states a Thales spokesperson. “We give special attention to all parameters [involved]. All identified checkpoints identified in the maintenance documentation of the equipment are therefore scrutinised in order to validate part replacements and failure correction.”

According to the spokesperson, the testing techniques used on these types of equipment range from static measures to use of a specific test bench which reproduces the environment (mechanical, electrical) in which the equipment operates.

HEICO’s senior director of marketing Kim Barmoha describes how her company approaches the task of dealing with these systems and the processes usually required. “Most avionic systems – flight control/flight management, navigation and communication systems on modern commercial aircraft – received for service have common failures that are typical for those LRUs (line replaceable units). The HEICO Avionics companies have built processes to continually evaluate and address these common failures and incorporate them into an engineered, preventative approach to the servicing of the units,” she explains.

“Most of the failures surround the power supply circuitry. For each component, HEICO companies Sunshine Avionics and Inertial Aerospace Services establish a multi-point checklist of items which are replaced as part of the preventative maintenance process,” Barmoha continues. “Most of these parts are the various capacitors and power filtering devices that are relatively low cost but have high failure rates. With this approach, we can help improve the on-wing performance of the units once returned to service and reduce total cost of ownership.”

As for the testing techniques used by the company, Barmoha states, “HEICO Avionics repair companies use the OEM-prescribed test equipment and testing steps to identify failures. We employ electronics engineers and experienced specialists as our repair technicians. These technicians apply prescribed and advanced isolation processes, developed for the specific units to verify and expose common and hidden failures that may not be fully understood using typical, go/no-go testing. Decades of experience is our most valuable tool in understanding and correcting the failures on these equipment types.”

The latest generation of aircraft have greatly increased levels of systems monitoring, with many more parameters being measured. Add the advance transmission of that data to airline maintenance departments and third-party MRO providers and some real benefits can be accrued.

So how much does in-service monitoring of electric and electronic systems help in preparing the maintenance shop for the work it has to do when units come off the aircraft? “On some equipment, such as starter generators which are connected to the avionics or digital control unit, there is built-in test monitoring that helps better track failure mode/cases,” states the Thales spokesperson. “With these new technologies, when a failure appears, we can save time [by being able to] anticipate on the failure detection analysis and therefore reduce shop processing time.”

Elaborating on how her company makes optimal use of the ability to examine data from the systems before an aircraft reaches the gate, Kim Barmoha notes, “In some cases, HEICO Avionics will partner with our airline customers’ engineering and reliability teams to monitor their avionics system performance and develop soft-time part removal programmes for preventative maintenance, so we can catch failures before they occur in service and potentially avert flight delays.” The value of that to an airline is, of course, considerable – both in actual operating costs and in maintaining brand value among customers.

“We in turn apply our engineered preventative maintenance approach to our service process to improve the on-wing life of the unit,” adds Barmoha. “During the repair process we can also provide feedback with analytical data about the performance of units under test, to help our customers make better decisions based on the health and service life expectancy of their equipment.” Again, therefore, cost savings are potentially available.

As noted, putting safety first is the mantra in aviation. Thus, when it involves keeping sophisticated systems airworthy, it’s always better to ask an expert.