Incident Overview
On 22 July 2014, a LET L410 UVP-E20, registration OK-WDC, operated by Silver Air spol s r.o., experienced an incident shortly after departure from Budapest Liszt Ferenc International Airport (LHBP). The aircraft was on a commercial cargo flight to Cluj-Napoca (LRCL) under instrument flight rules. About five minutes after takeoff, at an altitude of 4,200 feet, the primary flight display (PFD) malfunctioned. Both pilots detected an odor of electrical burn but no visible smoke. The pilot-in-command decided to return to Budapest. The crew informed air traffic control of technical reasons but did not declare an emergency (PAN PAN or MAYDAY). ATC authorized the return and alerted the fire service, though no intervention was required. The aircraft landed safely at 09:50 local time.
Inspection Findings
After landing, maintenance personnel found the housing of the left PFD instrument to be wet. No damage to the aircraft was reported, and there were no personal injuries.
Analysis
The investigation determined that rainwater leaked into the cockpit through a defective seal on the left windscreen. The water reached the top of the instrument panel and entered the instruments and their electrical cables. A short circuit occurred due to the water layer connecting cables and metal parts. The resulting current may have heated affected wires and interfered with equipment operation.
Causes
The incident was caused by:
- Rainwater ingress behind the instrument panel due to a leakage in the windscreen seal.
- Malfunction of the pilot-in-command's PFD instrument as a result of the water ingress.
Additional Information
Both pilots held valid licenses and medical certificates appropriate for the flight. The aircraft had a valid airworthiness certificate and was maintained according to requirements. No safety recommendations were issued as the investigation did not identify circumstances warranting them.