Corrosion inside the engines of a Hop A Jet Challenger led to an extremely rare simultaneous loss of thrust in both engines before the crew made an emergency landing on a highway in Naples, Florida, on Feb. 9, 2024. Both pilots were killed, but the flight attendant and two passengers were able to escape through a rear baggage door as fire started to consume the wreck. One person in a car struck by the plane was also injured.
The flight was uneventful until the pilots configured the big business jet for its final approach to Naples. As they turned to final, they reduced power and the engines rolled back to sub-idle and would not respond to control inputs. The crew told ATC they’d lost both engines and wouldn’t make the runway. The plane hit a sign on the highway that was not the type that breaks free on impact and that sent the Challenger across the road and into a concrete noise abatement wall.
The engines were sent to the manufacturer (GE) and techs found that corrosion inside the high-pressure compressor prevented the variable geometry controls for the compressor vanes from functioning properly. That resulted in the engines almost simultaneously entering unrecoverable sub-idle rotating stalls. The plane had spent almost its entire life in Florida and Barbados, and the corrosion had built up over time from the salty environment. Probable cause of the accident was determined to be “corrosion of both engines’ variable geometry (VG) system components, which led to their operation in an off-schedule position and resulted in near-simultaneous sub-idle rotating compressor stalls on approach, subsequent loss of thrust in both engines, and an off-airport landing.”
I admit to being skeptical as to this being the cause. Corrosion is a slow process generally and seldom occurs at the same rate everywhere. To have two engines fail simultaneously from an independent issue like corrosion seems so improbable that it is hard to accept that as the real cause. I still think their had to be some common issue such as fuel supply or such that could affect both engines at precisely the same time.
…and how did corrosion sufficient enough to cause this “simultaneous failure” escape detection? There has to be a lot more to this story than a couple of rusty parts.
That’s my thinking. Certainly the mathematics of probability allows such improbable events to occur, but the likelihood of this has to be virtually zero.
Probabilities for single fault tolerance would agree with your assessment. It would be highly improbable to have two separate but identical components fail at the same critical time; something like one in 100,000,000 hours of operation. But environmental corrosion reduces those margins by generating a common-cause failure probability, eliminating the odds for single fault tolerance.
There is more to the story. It’s covered in the final report.
Do yourself the favor of taking the time to read the NTSB final report number ERA24FA110. If you do you’ll find that both engines simultaneously sustained 8 hung starts during their lifetime with incomplete and therefore inconclusive troubleshooting results, the most recent of these occurring 25 days prior to the crash. Hung starts are a common occurrence in simulators during recurrent training. They are rare in live engines on the wing, and even more rare on both engines during the same start sequence and should be stirring up serious curiosity when they do occur.
The final report does state the very common knowledge, as you point out, that corrosion is a slow process. We all know that, but slow corrosion processes do not preclude failure 100% of the time. Improbable does not mean impossible, a fact which is convincingly concluded in the final report, as hard as that may be to accept.
Good points, John.
Well, if it really was corrosion and the engines were so bad that starts were hanging, we really need to find out who and how the maintenance was being done.
Maintenance procedures were also covered in the full report. In short, the troubleshooting procedure for a hung start did have a step that would’ve identified the problem. But it was far down the list and if the previous steps worked then it wasn’t performed. The manufacturer has since revised the procedure as a result of this accident.
Still, wouldn’t (shouldn’t) multiple, dual, simultaneous hung starts alert a real A/P to get factory involved and encourage a lot more in depth troubleshooting? Just because the pistol went click the first 5 times, and I checked those cylinders to understand why, doesn’t mean #6 will or won’t create a disturbance.
Read the report. GE was involved in the troubleshooting.
UPDATE: The previous posts to this topic just appeared when I posted my comment–the site showed 0 comments when I posted. Otherwise I would have just agreed to what others are saying.
I have read this probable cause before but I am still perplexed. If both engines are truly independent, how could corrosion on each engine just “happen” to reach the point of causing a failure at the exact same time? It seems like the corrosion damage on the engines would have to be “synchronized” to cause failure at the exact same point? I’m not questioning the probable cause–would just like more details.
P.S. We live in Naples. We were out driving and saw the accident scene just minutes after it occurred.
The answer is in the actual final report. Corrosion took place at the same rate over time on both engines and affected the airplane the same on both engines during their 8 hung starts previous to and finally during the simultaneous engine failures.
It sure seems unlikely that a corrosion issue would impact two engines simultaneously without another factor, such as the engines operated improperly just prior to the failure.
How many mechanical failures are there on a Challenger 600 that are capable of shutting down both engines simultaneously with a master warning and an “engine oil” EICAS and voice warning?
At least one.
The fact that the engine low oil pressure warning lights came on within a second of each other sounds more like a commanded or uncommanded engine shutdown sequence initiated by the power levers. Misrigging or accidental activation of the stop gates is far more likely than simultaneous corrosion buildup causing simultaneous sub idle rotational stalls or whatever they came up with.
The world is truly doomed. To have multiple aviation savvy readers simple doubt the result of a technical report because they “think” it just can’t be possible and they know better… well, sign of the times.
In today’s data rich world, there are plots and strip charts that remove all doubt in this report. I’d recommend those interested to review the docket for this accident and specifically the report of the engine manufacturer, GE. There is no doubt. I’m also blown away. I can’t think of a single other accident in aviation history off the top of my head resulting from simultaneous dual turbine engine failure stemming from a mechanical cause so insidious to the pilots. But the data is what the data is.
Tester, I agree with every word you wrote above with one exception, that word being “savvy”. Truly savvy readers might actually consider daring to believe in extensive evidence based conclusions drawn by professional investigators and factory propulsion engineers over the course of many months.. But no, since it’s improbable that corrosion could affect two engines in the same way on the same airplane in a corrosive environment, and because we’ve heard that all our lives, the improbable can’t be possible.
It’s kind of like the old J-3 Cub saying: “A Piper Cub is so safe it can only just barely kill you.” So if it can just barely happen, it can’t really happen and never will.
But it might be an encouraging sign of the times that people recognize that they have been lied to and deceived so often that they are now beginning to think for themselves instead of just believing every government report that comes out with a stamp that says “Official.” It might be too little, too late, but it’s still a good sign that people are questioning things rather than just believing everything that comes from sources in high places.
I don’t claim to understand all of the technical details about this Challenger accident and I don’t have adequate time to research it, but Critical and independent thinking is a survival skill for both pilots and anyone else that wants to survive. Believing everything the government says and never questioning it is a fast way to the graveyard for the whole country.
I can believe it, because I’ve seen it almost happen on climbout, on two different aircraft. Fortunately in both cases, the crew stopped the climb just in time to keep the second engine from failing, though they didn’t know it at the time.
Ditto on what many here are saying. Extremely unlikely that both engines corroded and had the same failure mode at the same time. Same with the hung starts.
NTSB: Keep looking.
Kudos to the flight attendant – she was sitting in the cockpit jump seat when she saw a lot of “red lights”. She may not have known what they were but knew it was bad. The pilots had their hands full so on her own she went back to the cabin, strapped in, and told the passengers to brace for impact seconds before they hit.
She tried both cabin doors before going to the aft baggage door. Another passenger was already trying to open it but she had them move aside, cleared a path, then opened the door and lead them out and away from the plane.
The kicker was she wasn’t trained on opening the baggage door. She had just watched the pilots doing it on earlier flights.
I can’t help but think without her there may have been more fatalities.
For some reason some of these comments remind me of the surprise I feel each year at how many people fly into Oshkosh without reading the NOTAM.
Kirk, you’ve accurately identified exactly that type of cohort. These are those.
I’m glad that people question official reports. Regardless of who is right and who is wrong about this Challenger dual engine failure at Naples. Remember captain Sully? He did a fantastic job of putting a jet in the Hudson River with no loss of life. I’m sure that he and every other pilot who taxied out that day read the NOTAM about millions of birds 🦅 in the immediate area and they all taxied out and got in line to takeoff anyway, because that’s what they were expected to do by official policy. Questioning it would have cost him his job. Millions and millions of people have marched to their death because they failed to question official policy. They were told that they could not question the official policy and or reports and they just believed it unquestioningly as they marched to their death. A good pilot questions everything that could possibly be a threat to safety.
Quaint. The best pilot’s take NTSB findings seriously and learn from them.
NTSB findings are definitely one of the sources that should be considered. But they should still be questioned in the light of common sense.
What’s your definition of “Questioning”?
Questioning official reports is a good thing. It’s the very basis of peer-reviewed science.
But is it really “questioning” when, as you admit, you “don’t…understand all of the technical details about this Challenger accident and … don’t have adequate time to research it”?
After all, if you’re asking questions but not looking for answers, what are you really doing?
Are you saying that the NTSB cannot ever be wrong?
It serves to question reports from the NTSB. They tend to publish the low hanging fruit; that which is defendable and suitable for litigation. But the nuances found in back-story understandings are far more explicit in how the cascading events arrived at the accident scene. The NTSB is a literal organization. It does not mean they should be taken literally.
“Are you saying that the NTSB cannot ever be wrong?”
You just answered a question with a question. Would my answer to your question change your answer to mine?
The article above is primarily conclusions with little explanation. It has to be, otherwise it would be 21 pages long… just like the NTSB final report.
So if your conclusion is based upon the article then it’s bound to be suspect because you don’t have all the information. You can find more answers in the NTSB final report. There’s no link to it in the article above but here’s a link to the final report (it will download a PDF):
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193769/pdf
It addresses the questions you raised about how two engines can experience simultaneous failures. And why the previous “hung start” investigations failed to find the problem.
Now you may still feel the NTSB got it wrong. But at least it’ll hopefully be a (more) informed opinion.
I’m sorry guys. I swear I added the full report to the bottom of the story but I don’t know what happened to it. It’s there now.
Russ you did include the La Guardia/Jazz preliminary report which may have led you to think you had included this final report as well.
Whether or not you included the final report here is beside the point. One would have thought that the degree to which some of the naysayers have spoken here, they would have pulled up the report and read it independently on their own. It’s pretty evident lots of that word salad spilled here was done so in total ignorance of the actual final report contents and details.
“Word salad…” Great metaphor!
Thanks Bill54494, but it’s not original with me. I’ll add that it has been used to describe my writing as well.
LOL!
Boy, the ego on some of these commenters. People who didn’t even read the full report let alone inspect the engines or put hands on them: “The report is suspect because it was unlikely for this to happen!” Come on guys, you’re putting on a Dunning-Kruger effect show here.
It not only makes sense for two engines with the same TSN, CSN, level of maintenance/pattern of neglect, and operating conditions to both experience the same failure in a similar timeframe, it’s probable. We’re talking about two complex machines that are as close to identical as is possible experiencing the a service life that is as close to identical as possible. Yes, corrosion is usually slow, did you read the report? Look at the FAA registry? A/W date 2-2-2005, original engines. These engines had almost 20 years of being based and operated in island and coastal environments to undergo corrosion, is that not slow enough for you? When you operate and store an aircraft in the coastal areas of FL and even worse, the islands, you’re doing a low intensity salt spray test whether you like it or not. In the islands, cars rust out and infrastructure corrodes almost as badly as in the rust belt of the US, just from the airborne salt spray. Florida isn’t as bad in this respect as Barbados, where the original operator was based, but in Florida, you can still live miles inland and see salt on your windows on a windy day. FXE is 5 miles from the beach. These engines had plenty of time for salt and moisture to accumulate in areas prone to it and cause corrosion between engine washes (if they were even performed). We see from the evidence in these engines that the 5th stage VSV bores are particularly vulnerable to this, we can speculate about this, maybe it’s because there’s a small amount of leakage blowing through and causing salt to accumulate in an area that is very difficult to clean adequately. In every engine there are operating conditions, particularly transients, where the engine is particularly vulnerable to compressor stall if margins are degraded and both of these engines had the same compromised VSV performance and seem to have entered one of those states without hope of recovering. It’s really not as shocking as many are making it out to be.