BOMBARDIER INC CL 600 2C10 near Kansas, IL — 2016-11-29

Probable cause

The probable cause of the uncontained No. 1 (left) engine failure was a separated high pressure turbine 2nd stage blade that failed due to a fatigue crack that originated below the blade platform from an area of corrosion.

NTSB narrative

The No. 1 engine experienced a catastrophic failure due to a separated high pressure turbine (HPT) 2nd stage blade. The separated blade subsequently damaged the HPT 2nd stage nozzle vanes, remaining HPT 2nd stage rotor blades, and all four stages of the low pressure turbine (LPT). Metallurgical analysis of the HPT 2nd stage blades that separated below the platform concluded that the first blade to separate failed due to a high cycle fatigue crack that originated from an area of corrosion on the convex side. Six additional blades separated below the blade platform at high cycle fatigue cracks that had transitioned to overload due to impact damage from the initial blade release. The remaining blades in the HPT 2nd stage separated above the blade platform due to overload consistent with secondary impact damage. Multiple blades that separated above the blade platform also had fatigue cracks present below the blade platform that originated from areas of corrosion. The corroded areas contained elements including: sulfur, sodium, potassium, and phosphorus, which are common corrosive elements. The source of the corrosive elements could not be identified. The engine water wash schedule was reviewed and according to GoJet Airlines, water washes are performed on their CF34-8C engines every 1,200 flight hours, or when engine trend data shows performance degradation. GE currently recommends water washing the engine at every -2A check, or about 1,600 flight hours. A GE service bulletin applicable to CF-348C engines is scheduled to be released in the first quarter of 2018 that increases the water wash interval to 2,000 flight hours or when engine trend data shows performance degradation.

Analysis

Primary failure mode

Mechanical failure

NTSB coding

• Uncontained engine failure · Enroute-cruise

Evidence available

• 3 docket documents

Docket documents3

• GE Aviation CF34-8 ESN 965352 HPT S2B Under-Platform Separations Materials Laboratory Reportform
• GE Aviation Metallurgical Evaluation of a CF34-8C LPT Case from ESN 965352 Operated by GoJetother
• Powerplant Group Chairman's Factual Reportreport

Related mishaps

• MX AIRCRAFT LLC MXS

  2018-03-25 · Fulton, TX