Pilot Debrief

RAYTHEON AIRCRAFT COMPANY 400A near Rochester, NY — 2014-03-13

Final reportENG14IA011
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Date
2014-03-13
Location
Rochester, NY, USA
Airport
ROC
Aircraft
RAYTHEON AIRCRAFT COMPANY 400A
Registration
N193BJ
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Takeoff roll

Probable cause

The probable cause of the uncontained No. 2 engine failure on the Raytheon Beechjet 400A was a herring gull birdstrike that resulted in fan blade contact with the inlet case and rub induced excitation of a previously unidentified natural frequency (resonance) within the engine operating range.

NTSB narrative

The No. 2 engine sustained a herring gull bird strike during takeoff climb from Rochester International Airport- Rochester, NY. The impact from the birdstrike resulted in contact between the fan and inlet case that separated eleven (11) of the nineteen (19) fan blades and subsequently led to the failure of the No. 1 bearing housing, and a midshaft fracture of the low pressure turbine shaft. Materials analysis on recovered fan blade fragments determined that all separated blades failed due to overload and no evidence of fatigue was identified. A series of modal tests including: tap hammer, high energy shaker, and computer model simulation were conducted at the system and component level. The tests identified a four nodal diameter coincidence at about 72% N1 speed. When sufficient energy is imparted to the engine fan during a foreign object ingestion event like a birdstrike, it may result in a rub induced excitation and subsequent fan blade separation and catastrophic engine failure.

Analysis

Primary failure mode
Mechanical failure

NTSB coding

  • Powerplant sys/comp malf/fail · Initial climb

Evidence available

  • 5 docket documents
View NTSB final reportView NTSB docket

Docket documents5

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