What happened
On February 27, 2023, at approximately 13:25 UTC, a Long-EZ aircraft, registration PP-ZEZ, was performing a local flight departing from Aeródromo Professor Urbano Ernesto Stumpf (SBSJ) in São José dos and Campos, Brazil. During the cruise phase of the flight, the aircraft experienced a significant loss of engine power. The pilot attempted to manage the emergency by activating the fuel pump in an effort to restart the engine, but the power loss persisted. The pilot subsequently performed an emergency landing in a rural area near Taubaté, São Paulo. The pilot sustained serious injuries, and the aircraft suffered substantial damage.
The investigation
CENIPA investigators examined the aircraft's digital flight data, which recorded engine parameters such as RPM, oil pressure, and fuel flow. The data revealed that the engine RPM began to drop at 13:17 UTC, followed by a peak in fuel flow when the pilot engaged the fuel pump. Crucially, the investigation ruled out a fuel starvation event, as the fuel flow remained stable for two minutes after the initial RPM decay. Additionally, the investigation found that oil pressure decreased in correlation with the RPM drop, which ruled out an engine failure caused by an oil leak.
The investigation also scrutinized the aircraft's maintenance records and the pilot's documentation. Investigators discovered significant discrepancies in the aircraft's logbooks, noting that several maintenance entries appeared to be backdated or improperly recorded in new logbooks. Specifically, some inspections were recorded in books that had been opened years after the actual maintenance took place. Furthermore, the investigation noted that the engine spark plugs had not been replaced since 2001, and the ignition wiring had not been replaced since 2002.
Findings
- The engine power loss may have been caused by carburetor icing, as meteorological conditions showed moderate risk for such an occurrence due to humidity and temperature levels.
- A secondary possibility is a failure within the ignition system, given the extremely long service intervals for the spark plugs and wiring.
- Inconsistencies were found in the aircraft's maintenance documentation, including unrecorded periods of inactivity and improper logbook numbering.
- The pilot's digital flight log was not up to date, with the last entry recorded in late 2021.
- The maintenance of the aircraft was identified as an undetermined contributing factor due to the lack of verifiable records for several years.