Hop-A-Jet is urging the Federal Aviation Administration (FAA) to tighten inspection requirements for General Electric CF34 engines after investigators linked a fatal Challenger 604 crash to undetected engine corrosion.
In its final report, the National Transportation Safety Board (NTSB) determined that corrosion within the engines’ variable geometry (VG) systems led to compressor stalls and a near-simultaneous loss of thrust in both engines as the aircraft approached Naples Airport. The crew attempted an emergency landing on Interstate 75, but the airplane struck roadside structures and was destroyed by fire. Both pilots were killed, while the cabin attendant and two passengers survived.
The FAA responded to the investigation earlier this year with a proposed airworthiness directive that would require borescope inspections and operational checks on certain CF34-series engines. The proposal applies to more than 1,100 engines used on Bombardier Challenger and regional jet aircraft.
In comments submitted to the FAA, Hop-A-Jet said the proposed directive should go further by mandating corrosion inspections, requiring inspection findings to be reported, and calling for additional inspections of engines previously cleared under procedures that did not directly examine corrosion-prone areas.
The company argues that operators had little ability to detect the issue themselves because the specialized inspections were conducted by the engine manufacturer or authorized maintenance providers using proprietary procedures. According to Hop-A-Jet, a post-accident review of archived borescope images revealed corrosion that had not been identified to the operator.
The company is also urging the FAA to consider additional safeguards for aircraft operating in coastal environments, where salt exposure can accelerate corrosion, and to provide clearer guidance for identifying hung starts and slow starts—engine-start anomalies that became a focus of the investigation.
Hop-A-Jet said its recommendations are intended to improve safety across the CF34 fleet and help prevent a similar accident from occurring in the future. The FAA is reviewing public comments on the proposed directive before issuing a final rule.
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