What happened
On July 21, 2017, an Embraer EMB-810C, registration PT-LKX, departed from the Francisco Beltrão Aerodrome (SSFB) for a ferry flight to Pato Branco (SSPB). Shortly after takeoff, while the pilot was initiating a right-hand turn, the left engine experienced a loss of power. The pilot reported that the manifold pressure for the left engine dropped to 15 inHg, well below the required operational parameters.
Unable to maintain altitude or return to the departure runway, the pilot attempted to level the wings and climb, but the aircraft continued to lose altitude. The pilot ultimately executed a forced landing in an unprepared field. During the descent, the aircraft struck the canopy of a tree before coming to a stop near a river. The aircraft sustained substantial damage, though the pilot emerged uninjured.
The investigation
CENIPA investigators examined the engines and the aircraft's maintenance records. While the left engine did not exhibit failure during ground testing, investigators found that activating the auxiliary fuel pump caused the engine to lose approximately 250 RPM and eventually stall due to an excessively rich mixture. This was attributed to the auxiliary pump switch being installed incorrectly (inverted) and improperly labeled.
Regarding the right engine, witnesses reported seeing dark smoke trailing from the engine during the flight. Subsequent bench testing revealed that the right engine's fuel pump was delivering 235 pph, significantly exceeding the maximum authorized flow of 140 pph. This excessive fuel flow caused the engine to operate with a rich mixture, evidenced by soot found on the cylinders and spark plugs, which likely contributed to the loss of power in the remaining engine.
Furthermore, the investigation identified an unauthorized "kill switch" installed behind the pilot's panel, which cut power to both engines' starters and the right engine's auxiliary pump. This modification had not been approved via a Supplemental Type Certificate (STC).
Findings
- The right engine was operating with an excessively rich mixture due to a malfunctioning fuel pump with a flow rate far exceeding manufacturer limits.
- The left engine's auxiliary pump switch was installed in an inverted position with inadequate labeling.
- Unauthorized modifications were present on the aircraft, including an unapproved electrical kill switch.
- Maintenance records for the airframe, engines, and propellers were not up to date.
- The pilot did not complete the full engine-out emergency procedure, specifically failing to feather the propeller on the failed engine, which increased drag.