How to Troubleshoot Avionics for Success
When a troubled plane comes in with an electrical issue, the first step is troubleshooting. The process starts with trying to understand – and when possible, replicating – what a customer is experiencing.
“Basically, trying to address what the customer has complained about, verifying their discrepancy. Sometimes customers may not have a clear knowledge base of the system and they just say, ‘This is not working.’ So then we've got to do our best to duplicate the electrical failure and then we can better assess what the problem actually is,” said Janson Finkbeiner co-founder/owner of South Carolina Avionics Services.
Finkbeiner said the challenging part about troubleshooting an electrical issue is duplicating what a customer has been experiencing. Fixing a hard failure is actually easier than troubleshooting a sporadic problem.
“Fixing intermittent problems can be very challenging. The nice part is that if it's broken, then it increases our ability significantly to fix the problem because we've duplicated essentially what they've found because it came in broken,” Finkbeiner said.
To get at the heart of the issue, Finkbeiner gives his customers an in-flight to-do list when an electrical problem arises.
“If it's electrical noise, I'm going to give them a list of items to do in flight and say, ‘Okay, we can't duplicate it on the ground, but when it does happen, turn these items on, turn these items off and see if it affects things. That would be in case of a calm electrical noise or things like that,” he explained.
Electrical noise is the most common issue that South Carolina Avionics Services is asked to address. Finkbeiner said they’ve found newer avionics to be extremely sensitive, requiring installation to the letter of the manual to avoid noise.
Once the avionics installation is ruled out as the culprit, Finkbeiner said the troubleshooting process may look as follows:
“We've had those problems where you got a twin engine airplane, you shut one engine down, problem goes away. Then you start them back up, shut the other engine down and the problem's still there. So we're saying, ‘Okay, we got a problem on the left engine.’ And then from there, we're able to say, ‘All right, it's only when the engine's running. Is it the charging system?’ Well, let's turn the charging system off while the engine's running and then oh, it doesn't affect anything. So, it's not the charging system. It has to be what's left on the engine and is going to be ignition,” he described.
The age of an aircraft can also be a determining factor.
“If we're dealing with the electrical system, we look at the age of the airplane and we also inquire in the logs how often have they replaced alternators and voltage regulators. They're components that should last a significant long time, especially the voltage regulators. I mean if it's wired properly, you don't change them that often,” he said.
He said that the industry is at a point where newer avionics and older avionics are no longer compatible.
“Additionally, there's a lot of the older avionics you just can't get reasonable serviceable repairs. Somebody may be able to try to fix it, but is it really worth the money and is it going to pay going forward? So our industry has changed massively where we're just gutting the panel and starting from scratch. Customers a lot of times get so focused on their wallet, they forget that, wait a second, you've got a 60-year-old airplane with original wiring and you don't have a car with that's 60 years old with original wiring,” Finkbeiner said.
Batteries
In their role of partially powering an aircraft, batteries are more straightforward and require far less, if any, upkeep. But problems still arise from time to time.
A typical malfunction for batteries arises from improper use and incorrect handling. If the battery is used in very cold or very hot temperatures repeatedly, or the battery gets dropped in the field, this can cause a “benign death,” meaning the battery voltage collapses and no power comes out, explained Tine Tomažič, Director of Engineering & Programs, Pipistrel.
“Propulsion batteries on the other hand, especially the ones Pipistrel uses in its airplanes, are different as we design them in-house. Each of those batteries comes with an elaborate battery management system (BMS). The BMS constantly monitors the battery and its functions, even when the battery is not engaged and the aircraft is off and parked,” he continued.
Typical causes of malfunctions in these batteries can be dissected into two areas. One is linked to hidden defects in battery cell production. These batteries are manufactured at large scale and from the approximately 1,000 cells in a pack, one of these cells might develop an error over time. The others are linked to external force as mentioned above where batteries might get dropped or are compromised during transportation.
To keep batteries working optimally, for chemistry-based lithium-ion propulsion batteries, it is best to avoid leaving an aircraft with a nearly full battery in a hot climate above 113 degrees Fahrenheit (45 Celsius).
“In this condition, the battery would self-discharge over time. It doesn’t cause damage immediately, but when repeated over a longer period of time, it will cause degradation of battery life,” said Tomažič.
The typical shelf life of a battery when kept out of these hot conditions is easily more than 10 years.
“If kept in warm conditions over 45 degrees Celsius, the impact can be quite dramatic and may cut down shelf life to as little as two years,” said Tomažič
When it comes to battery life depending on usage, these numbers can vary. Pipistrel’s first generation of batteries on the Velis Electro ran for around 500 hours of service life, the second generation already delivers considerably more than 1,000 hours of service life. In some cases, even up to 1,500 hours in operation.
“For Pipistrel’s batteries, an index between 0 and 100 determines a battery’s health. It doesn’t mean the battery is broken or damaged when at 0, but the battery will not exert the necessary performance. Put simply, takeoff power cannot be delivered anymore,” he said.
He notes to also not submerge batteries in water and to keep them out of the sun.
For troubleshooting battery issues, Tomažič said the skillset is moving away from straightforward mechanical work and more towards a more digitalized mode of work requiring a different set of knowledge.
“It will be an exciting transition over the next decade, where a lot of maintenance personnel and experts will have to onboard more IT skills in order to effectively fix and troubleshoot on an aircraft,” he continued.
