Flybe DH8D near Manchester on Oct 23rd 2013, multiple electrical system failures

A Flybe de Havilland Dash 8-400, registration G-JECJ performing flight BE-2066 from Edinburgh,SC (UK) to Brussels (Belgium) with 20 passengers and 4 crew, was enroute at FL250 near Manchester,EN (UK) when the crew received a "PUSHER SYSTEM FAIL" caution, worked the related checklist and agreed to continue the flight to Brussels. A few minutes later the flight purser inquired with the cockpit crew, whether everything was alright reporting the cabin lights started to progressively fail starting from the front of the cabin extended towards the back. The flight crew replied they had technical difficulties but were continuing to Brussels. A few minutes later the crew received "ELEVATOR FEEL" and "PITCH TRIM" cautions, the crw ran the related checklists and were about to select the related page on the first officer's multi function display (MFD), when the MFD failed. Two further cautions appeared, then the first officer's primary flight display (PFD) failed as well. The captain assumed control, the cautions were identified as TCAS and Yaw Damper caution messages. While reviewing the related checklists the first officer noticed the right hand generator showed zero load. Subsequently the cockpit lights and the right hand audio/radio control unit failed. The crew used the emergency torch light, which subsequently failed as well. The crew decided to divert to Manchester,EN (UK), declared PAN about 60nm from Manchester. While descending towards Manchester the flight director failed and several more caution messages appeared. The crew noticed the right hand hydraulic system showed zero quantity without any related indication and configured the aircraft early for landing, all hydraulic systems worked normally. The aircraft landed safely on Manchester's runway 23R with normal braking. By then the hydraulic quantity indication had returned to about 75% of normal and the crew decided to taxi the aircraft to the apron. The crew recalled about 25 different caution and warning messages during the flight.

The British AAIB released their bulletin that initial investigation results suggested a malfunction of the right hand starter/generator, which should have triggered relais K2 to operate and disconnect the right hand DC bus from the generator, however, it appeared the auxiliary contacts within the relais remained open preventing the disconnect of the main contacts and relais 21 to operate connecting the right hand DC-Bus to the left hand DC-Bus. Instead, the right hand DC-Bus drained the battery until the battery was depleted - the failure scenario as recalled by the crew was consistent with such a scenario.

The manufacturer inspected the contacts of K2 and found severe pitting on the auxiliary contacts. The examination of the parts by the manufacturer is still ongoing.