CF 18 down, Lethbridge, Alberta.
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...always nice to see that Martin-Baker equipment works as advertised, but the primary question remains as to why the CF-18 "system" failed in this mishap. After all, the primary purpose of this entire flyby/demo operation was to publicly show how great that CF-18 system works.
Video of the mishap is brief but revealing. It shows a low speed runway pass at very low altitude, with a smooth transition to a classic asymmetric stall (right wing drop) and a right yaw before nose low impact.
The aircraft stalled because it was flying too slow for those conditions. Lack of adequate speed might have been a piloting problem or some aircraft malfunction. A clean F-18 normally has lots of thrust available and flys well even on one engine.
Differing engine nozzle configurations seem abnormal. Spectators report that one afterburner engaged just prior to impact, and the impact video section indicates the left engine might have been in AB. A malfunction on one engine could account for all that, but absent any other obvious problems (smoke/fire, aircraft oscillations, etc) it seems a lower probability. Bird-strike is also possible, but likely would have been noticed by the many spectators.
It's also possible the pilot had one engine in idle and controlling thrust entirely with the other throttle... perhaps to demonstrate CF-18 single-engine capability (as part of the formal flyby practice, or merely to himself). That would account for nozzle difference and sudden use of only one AB (..and the quick yaw just before impact).
Getting behind-the-Power-Curve at low altitude can be big trouble, even for modern high-performance jet fighters.
Also, early flight testing (mid-1990's) of F-18E/F revealed a significant aerodynamic problem -- sudden uncommanded "wing drop" (asymmetric stall) during certain maneuvers; physical wing modifications corrected the problem... but perhaps the CF-18 has some similar behavior in unusual circumstances ?
Video of the mishap is brief but revealing. It shows a low speed runway pass at very low altitude, with a smooth transition to a classic asymmetric stall (right wing drop) and a right yaw before nose low impact.
The aircraft stalled because it was flying too slow for those conditions. Lack of adequate speed might have been a piloting problem or some aircraft malfunction. A clean F-18 normally has lots of thrust available and flys well even on one engine.
Differing engine nozzle configurations seem abnormal. Spectators report that one afterburner engaged just prior to impact, and the impact video section indicates the left engine might have been in AB. A malfunction on one engine could account for all that, but absent any other obvious problems (smoke/fire, aircraft oscillations, etc) it seems a lower probability. Bird-strike is also possible, but likely would have been noticed by the many spectators.
It's also possible the pilot had one engine in idle and controlling thrust entirely with the other throttle... perhaps to demonstrate CF-18 single-engine capability (as part of the formal flyby practice, or merely to himself). That would account for nozzle difference and sudden use of only one AB (..and the quick yaw just before impact).
Getting behind-the-Power-Curve at low altitude can be big trouble, even for modern high-performance jet fighters.
Also, early flight testing (mid-1990's) of F-18E/F revealed a significant aerodynamic problem -- sudden uncommanded "wing drop" (asymmetric stall) during certain maneuvers; physical wing modifications corrected the problem... but perhaps the CF-18 has some similar behavior in unusual circumstances ?
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A malfunction on one engine could account for all that, but absent any other obvious problems (smoke/fire, aircraft oscillations, etc) it seems a lower probability. Bird-strike is also possible, but likely would have been noticed by the many spectators.
Well done to him for realising his situation and doing something about it whilst he still had time. Hope he gets the beers in for the Squippers (chute) and Armourers (seat).
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The Hornet has never had any form of wing drop problem unlike the Super Hornet. It would seem that the aircraft was flying at a high angle of attack on the low side of the lift drag ratio sweet spot and thus required quite a bit of power to counter the drag. Lose an engine and suddenly not enough thrust is available to maintain height and angle of attack or to recover to level flight without loss of more height than was available in this case.
It's also possible the pilot had one engine in idle and controlling thrust entirely with the other throttle... perhaps to demonstrate CF-18 single-engine capability (as part of the formal flyby practice, or merely to himself). That would account for nozzle difference and sudden use of only one AB (..and the quick yaw just before impact).
The pics seem to confirm the RH engine has lost all power while the LH engine is at high power.
At the time of the lawn dart the LH engine has blocked airflow but still fuel which of course leads to the burning out the tail pipe.
I am surprised about some of the aircraft performance comments suspecting asymetrical thrust leading to uncorrectable roll. This machine having little lever arm effect. Of course if like the Mig bird ingestion mentioned earlier, at very low speed and altitude an engine failure might lead to little room for recovery.
At the time of the lawn dart the LH engine has blocked airflow but still fuel which of course leads to the burning out the tail pipe.
I am surprised about some of the aircraft performance comments suspecting asymetrical thrust leading to uncorrectable roll. This machine having little lever arm effect. Of course if like the Mig bird ingestion mentioned earlier, at very low speed and altitude an engine failure might lead to little room for recovery.
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Well, I had no intention of joining or posting as I was just doing some web surfing but I felt the need, the need for...a reply, sorry.
It is quite amazing that you have determined all of this from a quick clip of video. Without knowing the full story it is only speculation at this point. I have been flying Hornets for a number of years and in my personal speculation (Which I personally hate doing) it looks to me like something happened with his right engine. As the spectators mentioned a popping sound, this is a classic sign of a compressor stall, which was one of the reasons the design of the intakes on the Super Hornet were changed to provide better airflow at high AOA. While it does to appear to be a stall, the question needs to be answer how the stall occurred. That being said ...
Quite incorrect. Airshow manuevers are not done anywhere close to the edge of the envelope because of the extreme emphasis on the safety of those at the demonstrations. This particular maneuver is done at an altitude and AOA that the pilot has roughly a 50% chance of recovering the aircraft should they catastrophically lose an engine. Even if it is unrecoverable, they have enough time and authority to put the jet in a safe place before jumping out. As far as I know, this is the first time this has ever happened during this maneuver to a Hornet ever.
I would agree with this as a bird strike that would take out and engine would have made a lot more noise and if the engine catastrophically failed there would have a lot more evidence of that on the tape. Having personally watched a Hornet engine eat itself on a fan blade, it is quite a fireworks show. I won't get into the nozzle discussion but to say that it is something that is part of our instrument scan to ensure both nozzles are scheduling correctly.
Nope, simply not possible for reasons that mentioned above about safety. WWW said it perfectly in his long post and I agree whole heartily.
Sometimes bad things happen. That's why the procedures are in place. It's just a bunch of CF, wires, and metal. The pink fleshy body is the important part and it lives to fly another day.
If I were a betting man I would bet this will be the eventually outcome.
Originally Posted by DelaneyT
Video of the mishap is brief but revealing. It shows a low speed runway pass at very low altitude, with a smooth transition to a classic asymmetric stall (right wing drop) and a right yaw before nose low impact.
The aircraft stalled because it was flying too slow for those conditions. Lack of adequate speed might have been a piloting problem or some aircraft malfunction. A clean F-18 normally has lots of thrust available and flys well even on one engine.
Differing engine nozzle configurations seem abnormal. Spectators report that one afterburner engaged just prior to impact, and the impact video section indicates the left engine might have been in AB. A malfunction on one engine could account for all that, but absent any other obvious problems (smoke/fire, aircraft oscillations, etc) it seems a lower probability. Bird-strike is also possible, but likely would have been noticed by the many spectators.
It's also possible the pilot had one engine in idle and controlling thrust entirely with the other throttle... perhaps to demonstrate CF-18 single-engine capability (as part of the formal flyby practice, or merely to himself). That would account for nozzle difference and sudden use of only one AB (..and the quick yaw just before impact).
Getting behind-the-Power-Curve at low altitude can be big trouble, even for modern high-performance jet fighters.
Originally Posted by lomapaseo
The pics seem to confirm the RH engine has lost all power while the LH engine is at high power...
...at very low speed and altitude an engine failure might lead to little room for recovery.
...at very low speed and altitude an engine failure might lead to little room for recovery.
Aperson
The noise that a bird strike makes is the noise of an engine stall. So if the engine compressor ate the bird for lunch that's all you would get or see.
I do agree however that if it's the fan that breaks than the Titanium sparks out the bypass will make a big lightshow. However by now the safety office probably already knows what broke and I don't mean to get ahead of them
The noise that a bird strike makes is the noise of an engine stall. So if the engine compressor ate the bird for lunch that's all you would get or see.
I do agree however that if it's the fan that breaks than the Titanium sparks out the bypass will make a big lightshow. However by now the safety office probably already knows what broke and I don't mean to get ahead of them
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Yeah, you are totally correct, I was trying to get across that if it was a small bird, it likely wouldn't have done enough damage that quickly. We have had many a bird strike where the aircrew didn't know until they landed and saw the blood trail down the intake. A bird would have to big enough to essentially cause a fan blade to be thrown I would think, but as you said, we ain't the experts on this subject.
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The Hornet high alpha pass is designed to be flown at 25 alpha which would allow a recovery from a single engine failure. However, there are still alot of things that have to happen correctly in order to recover successfully. One issue not working in Boozers favour that day was the very high density altitude. Just glad that Boozer is ok and will return to flying soon.
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Can anyone confirm whether a Canadian study found the benefits of twin-engines (specifically in the CF-18) over a single engine to be insignificant - whatever problem caused the loss of one engine generally damaged the other as well?
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The USN would find any such study to be very suspect, as its experience (with far more aircraft over vastly more operating hours) is that very few incidents of both engines failing are due to any cause other than fuel starvation (or battle damage).
The USN has, on the other hand, had thousands of single-engine failures (including where the engine came apart and damaged surrounding structures) where the second engine either brought the aircraft back or kept operating until the aircraft became unable to fly due to other reasons.
I am aware of close to a score of aircraft that returned to either the base or carrier where I was stationed with one engine out, but in that time only 5 twin-engined aircraft from those bases were lost... three of those at sea with no communication from the crew to indicate what caused the crash, one was damaged beyond repair in an airshow accident caused by pilot disorientation leading to pilot error, and one of those was due to a pair of pliers left in the aircraft during depot-level repair jamming the elevators at a slight down angle (the crew attempted to regain control for several minutes before ejecting as they dropped below 2000' agl in a wings-level attitude with both engines running).
The USN has, on the other hand, had thousands of single-engine failures (including where the engine came apart and damaged surrounding structures) where the second engine either brought the aircraft back or kept operating until the aircraft became unable to fly due to other reasons.
I am aware of close to a score of aircraft that returned to either the base or carrier where I was stationed with one engine out, but in that time only 5 twin-engined aircraft from those bases were lost... three of those at sea with no communication from the crew to indicate what caused the crash, one was damaged beyond repair in an airshow accident caused by pilot disorientation leading to pilot error, and one of those was due to a pair of pliers left in the aircraft during depot-level repair jamming the elevators at a slight down angle (the crew attempted to regain control for several minutes before ejecting as they dropped below 2000' agl in a wings-level attitude with both engines running).
Last edited by GreenKnight121; 2nd Aug 2010 at 00:29.
Well you can also add in the twin pods of the B52's and B1 etc.
very few cases of taking out both podded engines even with non-containments from one engine to the other. The biggest problem was correctly identifying and handling fire detection issues and not shutting down a good engine.
The ruskies have a bit of data on this as well.
very few cases of taking out both podded engines even with non-containments from one engine to the other. The biggest problem was correctly identifying and handling fire detection issues and not shutting down a good engine.
The ruskies have a bit of data on this as well.
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You don't put a second engine into a fighter in case one of them fails!
But single engined fighters have substantially more redundancy built into them and their ancilliaries.
Although the F-16 is the only modern single-engined fighter operated in the west built in any numbers, since the early 90s, the ratio of single vs twin/multi engined aircraft losses due to engine failures is at virtual parity.
But single engined fighters have substantially more redundancy built into them and their ancilliaries. Although the F-16 is the only modern single-engined fighter operated in the west built in any numbers, since the early 90s, the ratio of single vs twin/multi engined aircraft losses due to engine failures is at virtual parity.
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Great to see and hear his recollection.
I'm surprised he didn't thank the Pprune Armchair Aviators for their help in discussing what he did wrong.
I'm surprised he didn't thank the Pprune Armchair Aviators for their help in discussing what he did wrong.