A regional passenger flight in Scotland experienced a sudden and alarming electrical failure shortly after takeoff, briefly leaving the cockpit displays dark and triggering a major safety investigation that took years to conclude.
On August 27th 2022, a Loganair ATR 42-500, registration G-LMRC, operating flight LM-72 from Aberdeen to Sumburgh Airport, was climbing out of Aberdeen Airport when the crew encountered multiple electrical faults. During the climb the pilots halted the ascent at approximately 10,500 feet after both Pratt & Whitney PW127 engines suddenly indicated zero torque.
At the same time, the aircraft’s electronic flight displays went completely blank, leaving the crew temporarily without their primary cockpit instrumentation. Although the displays returned after a short period, some system faults remained active.
The crew descended the aircraft to 5,000 feet and maintained that altitude for several minutes while assessing the situation before returning to Aberdeen. About 35 minutes after departure, the aircraft landed safely on runway 34 without further incident.
The incident was classified as a serious occurrence by the Air Accidents Investigation Branch (AAIB), which opened a formal investigation. Early findings pointed to a malfunction involving the aircraft’s 1PA electrical contactor, a component responsible for supplying backup power to the emergency electrical network. The aircraft manufacturer later issued an operational advisory in October 2022 recommending operators perform tests on the 1PA contactor across the fleet.
The issue drew regulatory attention. In October 2023, the European Union Aviation Safety Agency issued Airworthiness Directive 2023-0181 requiring operators of ATR aircraft to conduct operational testing of the 1PA contactor and repeat the test at 1,000-hour intervals.
On the third anniversary of the event, August 27th 2025, investigators released an interim statement confirming that extensive ground and flight testing had been conducted in an attempt to better understand the electrical failure. A final report followed on March 5th 2026.
The final investigation determined that the aircraft experienced a brief loss of electrical power from the DC standby, emergency, and essential buses—critical parts of the aircraft’s emergency electrical network—for about three seconds. Evidence from crew reports also suggested that DC BUS 2 either lost power or experienced an undervoltage condition during the same period.
Examination of the aircraft identified that the 1PA contactor had become stuck in an intermediate position when energized. This prevented it from supplying backup power to the emergency electrical network, making it a contributing factor to the severity of the event, though investigators determined it was not the root cause of the initial power loss.
Investigators explored several possible causes, including faults involving the battery switch or wiring between the battery switch and associated control units, but no such failures could be confirmed. The loss of power occurred twice—once in flight and again later on the ground—when the landing light switches were turned off. However, inspections revealed no faults in the landing light relays or the lights themselves.
The aircraft manufacturer also examined the possibility that electrical feedback from the landing light relays caused the failure, but the duration of such electrical effects was considered too short to account for the event. Nonetheless, investigators noted that previous incidents involving ATR 72-500 aircraft had reported similar cockpit display losses when landing lights were switched off. In two of those earlier cases, replacing the aircraft’s battery switch resolved the problem.
Although the exact cause of the power loss on G-LMRC could not be definitively identified, investigators noted that no further occurrences happened after the aircraft’s battery switch, landing light relays, and the 1PA contactor were replaced. This suggests that one or more of those components may have contributed to the failure sequence.
Because a longer duration power loss could have far more serious consequences—particularly during night operations or in instrument meteorological conditions—the AAIB issued a safety recommendation urging the aircraft manufacturer to continue investigating the potential causes of the electrical failure.
In response, both the manufacturer and EASA implemented safety measures requiring testing and replacement of faulty 1PA contactors across affected aircraft fleets, aiming to prevent a repeat of the potentially hazardous event.
