![The Hop-A-Jet Challenger 604 involved in the 2024 crash. [Credit: Hop-A-Jet Worldwide Charter]](https://www.flyingmag.com/wp-content/uploads/sites/2/2026/05/823-Image.jpg)
The only good thing that can come out of an aviation accident is the information learned through a subsequent investigation, which can be used to make aviation safer.
That’s the attitude of Barry Ellis, president of Hop-A-Jet, in response to the National Transportation Safety Board’s final report on the 2024 crash of a company jet in Florida. The NTSB determined the probable cause of the accident to be corrosion found in the engines.
The Hop-A-Jet-operated Bombardier Challenger 604 was on a 5-mile final to Runway 23 at Naples Airport (KAPF) when both engines began to lose power. The aircraft came down on a freeway at rush hour and caught fire. The pilot and copilot were killed, while the cabin attendant and the two passengers escaped through the baggage compartment door with minor injuries. A motorist was also injured.
The NTSB determined the probable cause of the dual engine failure was corrosion found in the GE CF34-3B engines’ variable geometry (VG) system. The corrosion blocked the airflow through the high-pressure compressor (HPC). Lack of airflow can cause a compressor stall and loss of engine power.
The corrosion prevented fluid movement of the variable guide vanes, and therefore, the VGs did not function as intended causing the dual rotating compressor stalls.
Per the NTSB report, extensive corrosion was also found in the HPC case VG stage 5 stator vane spindle bores, along with reduced angle swing range of the VG stage 5 stator, resulting in the VG position being more open when commanded fully closed and more closed when commanded fully opened. Other complications included slower than normal VG system response when tested with pressurized air, and VG stage 5 stator vanes unable to fully travel as specified by maintenance practice manuals.
At the conclusion of an accident investigation the NTSB routinely issues recommendations for changes in procedures or training design to reduce the probability of a similar accident happening in the future. However, according to Ellis, this time the agency did not issue many recommendations, in part because GE made changes to their procedures—outlined in service bulletins (SBs)—before the final report was issued. The changes include more frequent and detailed inspections of engines using a borescope.
“They accomplished the majority of what’s needed to not have this happen again,” Ellis said, adding that it is his understanding that the FAA will be issuing a Notice of Proposed Rulemaking (NPRM) for an airworthiness directive (AD) making the procedures developed during the accident investigation regulatory in nature.
The NPRM for the AD was released Thursday morning. The AD requires performing certain restart tests and, depending on the results of the tests, additional actions. In addition the AD as proposed would also require performing a borescope inspection (BSI) of the HPC case for corrosion and, depending on the results, a VG system functional check for pressure evaluation.
This proposed AD would also require, depending on inspection results, performing a force gauge test on the feedback cable for tightness, a visual inspection of the VG system for obstruction and, if necessary, removal of the engine from service. The AD would also require revising the airworthiness limitations section (ALS) of the existing engine maintenance manual to incorporate the VG system functional check.
Enhanced Crew Training
Per the NTSB report, approximately one month prior to the accident the jet experienced an abnormal engine start, which is known as a “hung start,” where the engine lights off but fails to accelerate to self-sustaining idle speed. It can be caused by insufficient power to the starter or starter air pressure that is too low to accelerate the engine to a self-sustaining speed, premature starter deactivation, a poorly performing or damaged compressor, incorrect scheduling of bleeds or stator vane position, or fuel issues.
The issue was reported to Hop-A-Jet’s maintenance department, but the technicians could not duplicate the condition. They consulted with the technicians at GE, said Ellis. Then Hop-a-Jet maintenance crews spent three days running the engines, draining fuel from the engines and testing it for contamination (none was found), and replacing the fuel filters and doing a visual inspection of the old filters. The next day both engines started normally, and multiple functional checks were performed with no anomalies noted.
The NTSB cited inadequate fault isolation guidance from the engine manufacturer, which prevented the identification of corrosion buildup in VG system components during troubleshooting of hung start events of both engines about one month before the accident.
Ellis said Hop-A-Jet has made procedural changes for pilots when an engine start anomaly is uncovered.
“We have done a number of training exercises with regards to hung starts and the differences between a hung start and a slow start and a hot start,” he said. “Because with the typical pilot, if he or she has a starting issue of any type, whether it be that it’s a slow start or a hung start, the first thing that they’ll do will be they’ll shut everything down and try it again. And that is now not the procedure that General Electric has incorporated into the service bulletin and the procedures.
“Now if you have a hung start, it stops right where you are. Contact your maintenance department, because it is a red flag that there could be a problem with the variable guide based system on the airplane. The hung start situation is the leading indicator that you have a potential variable guide vane system issue on these engines.”
Hop-A-Jet has also revamped the training for cabin crew to include teaching everyone how to access the baggage compartment. The cabin attendant of the accident flight had not received formal training on how to do this, but had the knowledge because she assisted the flight crew with loading baggage.
“Now everyone’s trained on how to access and open the baggage compartment, and we have trained everybody on how to use the baggage compartment as egress,” Ellis said. “The other thing that we’ve done is we have recognized that accessing that door, that exit from the aircraft, is only possible if you haven’t stuffed the baggage compartment full to the brim with bags, which on an airplane that holds 10 to 12 passengers, you oftentimes have a lot of luggage to carry. So we’re always cognizant now of how much luggage we’re carrying.”
Lawsuit in the Works
In October 2025, Hop-A-Jet and two of its subsidiaries filed a lawsuit against GE Aerospace in the U.S. District Court for the Southern District of Florida. The complaint places most of the blame for the crash on GE Aerospace, the maker of the CF34-3B engines used by Bombardier’s Challenger 600 series.
“It is now evident that this engine failure was caused directly by an inherent defect in this family of GE engines,” the lawsuit states. “Much worse, GE knew about this specific engine defect (corrosion to this family of engines) for many years, and in fact, took efforts to cover it up by hiding incriminating evidence (such as video of the GE secret inspection).”
The complaint also alleges that GE failed to inform operators of the CF34’s possible problems and revised its service contracts to exclude full corrosion coverage.
GE did not return FLYING’s request for comment.
