Incident Overview
On 1 November 2015, at approximately 15:05 local time, a Piper PA-28-181, registered as HB-PJP, was on a private visual flight rules (VFR) flight from Neuchâtel (LSGN) to the same airport. The pilot and one passenger were on board. While cruising at 4600 ft AMSL over the western sector of Payerne military aerodrome (LSMP), which was not active that day, the pilot noticed smoke entering the cockpit and a strong odor of burnt plastic. The anomaly was localized under the seats and became persistent. The pilot announced his intention to perform a precautionary landing at Payerne. The aircraft landed normally at 15:09.
Investigation Findings
No immediate troubleshooting or technical intervention was performed on the aircraft. On 2 November, the pilot reported the precautionary landing to the Swiss Transportation Safety Investigation Board (SESE). The following day, maintenance technicians accompanied by a SESE investigator examined the aircraft. They found that the potentiometer knob for the "NAV LIGHT and RAD LIGHT" control, located to the left of the battery and alternator switches, was in the engaged position. Inspection of the electrical wiring revealed burn marks on a multiple connector and its associated wiring. The connector, located centrally behind the instrument panel, was part of the navigation light and dashboard lighting system and was identified as the source of the smoke.
Aircraft Condition
The aircraft was manufactured in 1993 and had previously been registered in the USA, Germany, and Poland before being imported and registered in Switzerland in May 2015. During the investigation, several irregularities were noted:
- The Airworthiness Review Certificate (ARC) had expired 68 days before the incident (valid until 24 August 2015).
- Technical documents, including the aircraft technical log and Pilot Operating Handbook (POH), were not up to date; various certificates were missing.
- The required metal identification plate was missing from the aircraft.
- The last 100-hour inspection before import was on 27 August 2013; no evidence of a 100-hour or annual inspection in 2014 was found. A 100-hour inspection was performed in Switzerland on 10 September 2015.
- Placards in the cockpit and on the airframe were not in English, contrary to the POH.
- The circuit breaker panel and radio call placard were not in accordance with the POH.
- The pre-takeoff checklist placed under the engine gauges was in a foreign language and not per the POH.
The Swiss Federal Office of Civil Aviation (FOCA) had not performed an inspection of the aircraft upon import; official papers were issued based on the Polish-issued ARC under EASA regulations. The report noted that this case demonstrates the inadequacy of those regulations.
Subsequent Measures
Following the incident, FOCA implemented several measures:
- A technical inspection was carried out by a FOCA inspector to renew the ARC.
- Aircraft operators are now warned three months before ARC expiry.
- FOCA is cataloging and analyzing expired ARCs.
- In future, FOCA will perform an ACAM (Aircraft Continuing Airworthiness Monitoring) examination before issuing aircraft papers.
FOCA clarified that while it generally accepts aircraft from other EU member states without additional inspection, it reserves the right to perform an ACAM examination based on risk analysis, especially given issues noted with certificates from other EU states.