Incident Overview
On 22 August 2014, at approximately 19:15 local time, a privately owned F177RG aircraft, registration HB-CDE, was conducting instrument landing system (ILS) approaches for training purposes at Lahr (EDTL) under visual flight rules (VFR). A safety pilot was on board. During the second approach, while intercepting the localizer at about 4000 feet QNH, the pilots observed yellow smoke emerging from beneath the instrument panel, accompanied by the smell of burnt plastic.
Cockpit Indications and Actions
Shortly thereafter, the primary flight display indicated that electrical power was being supplied by the battery, and the avionics failed. The pilots initiated an immediate descent toward the airport, closed the firewall shutters, opened the windows, and performed the emergency checklist. After switching off the master avionics switch, they attempted to contact the control tower using a portable radio, transmitting a Mayday call, but the tower did not understand the message. All other instruments showed normal parameters. After assessing the risks, the crew decided to continue the approach. They extended the landing gear using the emergency procedure and landed on runway 21 without deploying flaps. Both occupants were uninjured.
Post-Flight Inspection
An inspection of the aircraft revealed that the seal of the cigarette lighter, which was powered directly from the primary electrical bus without a circuit breaker, had failed. This allowed the insulation of adjacent wires to chafe, causing a short circuit that led to the smoke and electrical failure.
Personnel and Aircraft Damage
Neither the pilot nor the safety pilot sustained any injuries. The aircraft sustained damage to the insulation of several wires and parts of the floor. No third-party damage occurred.