Add reduced battery capacity to the list of technical issues that airline maintenance staff should watch for in planes stored for long periods because the coronavirus has limited flying.
More than 30% of the global passenger jet fleet, or about 8,100 aircraft, remains in storage, according to airline analytics and consulting firm Cirium.
Last month, Airbus and the European Union Aviation Safety Agency issued an advisory that battery systems on A320, A330, A340 and A380 aircraft may not fully recharge after inactivity and lead to a power loss during operation.
During maintenance checks for parked aircraft the batteries are physically disconnected and reconnected. Nickel-cadmium (Ni-Cd) batteries disconnected from the electrical system self-discharge due to an electrochemical phenomenon, inducing a reduction of battery capacity. When the battery is charged again from the aircraft, the battery does not recover 100% of its initial capacity and battery capacity progressively decreases after each reconnection, according to an EASA safety information bulletin.
“This reduction of capacity cannot be reversed by the normal aircraft charging system, and the reduction in total capacity cannot be detected without the battery being sent to an approved battery shop for a battery recharge check or overhaul.
“As aircraft batteries are the final power source available to aircraft, this reduction in capacity of the Ni-Cd batteries may not meet the minimum battery endurance certification requirements when the aircraft is operated again, which may lead to a premature total electrical power loss in the case the aircraft’s main electrical system fails,” the bulletin said.
Airbus and EASA recommended airlines review their electrical system designs and their storage instructions to determine if the battery system can tolerate successive reconnection cycles without suffering from the same problem, noting that battery drainage is not an issue in all aircraft