Pilot Debrief

CESSNA 525B near Gulf of Mexico, GM — 2023-03-30

Final reportERA23FA174
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Date
2023-03-30
Location
Gulf of Mexico, GM, USA
Airport
TPA
Aircraft
CESSNA 525B
Registration
N869AC
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Descent

Probable cause

The separation of the left wing extension and winglet for reasons that could not be determined based on the available evidence.

NTSB narrative

The business jet was equipped with wing extensions (via supplemental type certificate) that included winglets and wing extension-mounted aerodynamic control surfaces that automatically deployed to counteract measured structural loads. Before the airplane’s descent from flight level (FL) 310, the weather was clear with no turbulence. When the airplane was descending through FL 300 for FL 270, the pilot felt “two jolts of sudden turbulence” that he described as a negative G followed by a significant positive G twice in the span of about 1 second. The pilot noted that the airplane was yawing, and he subsequently observed that the left winglet had separated, resulting in substantial damage to the airplane. He declared an emergency and landed without further incident at a nearby airport. Review of automatic dependent surveillance-broadcast and GPS revealed that, during the airplane’s descent, its airspeed was slightly outside the airplane manufacturer’s maximum operating speed (VMO/MMO) performance envelope. At the time of winglet separation, the airplane was descending about 5,300 ft per minute at 275 knots calibrated airspeed. Eleven days after the accident, the separated winglet was recovered from the Gulf of Mexico; however, the section of the left wing extension that included the aerodynamic control surface was not recovered. Metallurgical examination of the recovered components revealed overstress features and no evidence of fatigue. Additionally, systems testing of the aerodynamic control surface control units, the system computer, and the enhanced ground proximity warning system revealed no anomalies. Because the aerodynamic control surface on the left wing extension was not recovered, the reason for the left wing extension and winglet separation could not be determined.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have reduced speed earlier to stay within operating limits.

NTSB coding

Evidence available

  • ADS-B / radar
  • Photos
  • 18 docket documents
View NTSB final reportView NTSB docket

Docket documents18

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