If you're scud-running, don't follow rising terrain.
I don't know John, I have heard tell they claim it was deliberate to protect against over-stressing the airframe but that was refuted by others who said they just hadn't got their sums right - who knows?
On the 365 with dual hyd systems the piston areas are deliberately different so that the system powering the top half of the jacks collapses first, giving the LIMIT light and gong in the cockpit, so maybe it is a design philosophy after all.
On the 365 with dual hyd systems the piston areas are deliberately different so that the system powering the top half of the jacks collapses first, giving the LIMIT light and gong in the cockpit, so maybe it is a design philosophy after all.
Apologies if already mentioned. Obviously little or no visual references but Is It possible he slowed down so much he lost translational lift, ran out of power and helicopter started to descend.
I’m not familiar with this version of the aircraft it’s power and weight at the time. Or altitude and wind strength or direction.
R
I’m not familiar with this version of the aircraft it’s power and weight at the time. Or altitude and wind strength or direction.
R
He was going pretty slowly when he crossed the ridge and there is no sense of a sudden power demand or Nr decay - it just looks to me as if he realised he had made a big mistake and tried to turn left go back to re-cross the ridge - unfortunately the terrain and foliage got in the way of that.
I am with Crab here. That was just lousy flying. Maybe there wasn't any translational lift left, but you have to plan for that. Instead of trying to go 45 degrees or less, he just flew over the ridge, and got trapped. He did not leave himself an escape route.
Judging by the rant of that politician, pressure from the customer might have been a factor here.
And I am almost afraid to mention that, but in a Swiss forum somebody suggested that it was VRS. My comment wasn't published - debunking it obviously - probably because my tone was too annoyed.
Judging by the rant of that politician, pressure from the customer might have been a factor here.
And I am almost afraid to mention that, but in a Swiss forum somebody suggested that it was VRS. My comment wasn't published - debunking it obviously - probably because my tone was too annoyed.
An actual hydraulic failure with empty accumulators would lead to the same result of a rapid climbing roll which will get your undivided attention.
I agree with Crab and other comments. Looks to me like he slowed down lost translation and lost NR pulling the collective. The horn is on well before he hits the tree and I suspect the left yaw is not intentional but rather LTE as his rotor droops.
That was my initial impression.
Incidentally I think it is astounding there was even a single survivor let alone everyone on board. That’s a long drop after it hits the tree before hitting the ground.
That was my initial impression.
Incidentally I think it is astounding there was even a single survivor let alone everyone on board. That’s a long drop after it hits the tree before hitting the ground.
Last edited by SLFMS; 24th Aug 2022 at 09:26.
The 'good' thing about this accident, aside from fatality free outcome, is that the lead-up to it occurring was captured on video so that any trainee pilots (helicopter or otherwise) can see how rapidly the situation turns nasty for VFR into IFR conditions. Hope the video finds its way into pilot training material. Reminds me of another video involving a wedding party flying in an R44 (Title: "Bride Killed in Helicopter Crash (Warning: Distressing Footage)") in what looked like IMC conditions when it crashed. Sadly the outcome 4 fatalities in that case.
Thread Starter
The 'good' thing about this accident, aside from fatality free outcome, is that the lead-up to it occurring was captured on video so that any trainee pilots (helicopter or otherwise) can see how rapidly the situation turns nasty for VFR into IFR conditions. Hope the video finds its way into pilot training material. Reminds me of another video involving a wedding party flying in an R44 (Title: "Bride Killed in Helicopter Crash (Warning: Distressing Footage)") in what looked like IMC conditions when it crashed. Sadly the outcome 4 fatalities in that case.
- just sayin'
Crab, I’ve always been curious as to why Eurocopter/Airbus didn’t either provide larger servo piston area or higher pressure pumps to eliminate the jack stall possibilities stemming from high control load maneuvers? I.e., accept the higher vibratory control loads, include them in the fatigue calculations usage spectrum, and accept a probably small reduction in component replacement time?
Well, that R44 video has been out for some time now and it didn't stop this pilot from scudd-running.
- just sayin'
- just sayin'
Surely because it would effectively over engineering the system, and adding weight, for a situation that is effectively outside of the normal operating envelope? Not sure about the normal 365 but in the EC155 they installed an accumulator on the back right (?) servo unit to cater for a single hydraulic system failure during a steep turn and allow you to return to level flight.
I'm at the other end of the flying spectrum, (airliners), and have no knowledge of the sort of flying here, so could someone explain the probable sequence of events?
It looks to me that once over the ridge, he yawed or turned left and then hit a tree. So, why do we think he turned left and why did he descend - was he hit by a downdraught? or rollers?
Comments about losing lift followed by increasing collective and then decaying Nr - would not the engine(s) spool-up to compensate for the extra load, or was the helicopter too close to the ground for this to happen in time? He seemed to be very close to the terrain.
Just curious about the physics of helicopters.
It looks to me that once over the ridge, he yawed or turned left and then hit a tree. So, why do we think he turned left and why did he descend - was he hit by a downdraught? or rollers?
Comments about losing lift followed by increasing collective and then decaying Nr - would not the engine(s) spool-up to compensate for the extra load, or was the helicopter too close to the ground for this to happen in time? He seemed to be very close to the terrain.
Just curious about the physics of helicopters.
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I'm at the other end of the flying spectrum, (airliners), and have no knowledge of the sort of flying here, so could someone explain the probable sequence of events?
It looks to me that once over the ridge, he yawed or turned left and then hit a tree. So, why do we think he turned left and why did he descend - was he hit by a downdraught? or rollers?
Comments about losing lift followed by increasing collective and then decaying Nr - would not the engine(s) spool-up to compensate for the extra load, or was the helicopter too close to the ground for this to happen in time? He seemed to be very close to the terrain.
Just curious about the physics of helicopters.
It looks to me that once over the ridge, he yawed or turned left and then hit a tree. So, why do we think he turned left and why did he descend - was he hit by a downdraught? or rollers?
Comments about losing lift followed by increasing collective and then decaying Nr - would not the engine(s) spool-up to compensate for the extra load, or was the helicopter too close to the ground for this to happen in time? He seemed to be very close to the terrain.
Just curious about the physics of helicopters.
I was taught to fly fixed wing first because it was simpler, and required much less skill than flying a helicopter. So the weakest pilots were not allowed to advance to rotary wing, they had the option of fixed wing or ground crew!
For a simple analogy, fixed wing pilot pushes the weather limit on landing, cocks it up, and decides to go around too late. 🙀
You seem to be reading-in sone sort of negative attitude on my part?
Not at all; I am just saying I have never flown helicopters but want to understand what went wrong here.
Not at all; I am just saying I have never flown helicopters but want to understand what went wrong here.
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Facts remain the same in any form of aviation, poor judgment in poor weather will result in a poor outcome !
Avoid imitations
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It's no different to a light fixed wing aircraft. It looks like he flew himself into a classic CFIT.
After crossing the ridge and met with IMC, it appears that the pilot attempted to power his way out. Unfortunately, the aircraft didn't have enough engine performance and by continuing to pull collective pitch, the engine topped out, followed by the rotor RPM decreasing - which is known as "over pitching". At that stage the aircraft stops climbing (effectively the rotor blades are beginning to stall) and directional control in yaw decreases because the tail rotor is geared to the main rotor and suffers in the same way. Game over.
Had he approached the ridge at an acute angle, he could have left an escape route off to one side with known visual cues (because he had just flown past them). I used to teach my students never to fly to a ridge at 90 degrees.
Even in good visibility, if something goes wrong, such as engine failure in a single, or partial power loss in a twin, or even just a lack of sufficient power to make the angle of climb (such as in encountering a down-draught), you have a ninety degree turn to make to escape the rising ground and have to decide which way to go. Approaching a ridge at an acute angle, the escape turn need only be a small one - and you already know which way to turn.
After crossing the ridge and met with IMC, it appears that the pilot attempted to power his way out. Unfortunately, the aircraft didn't have enough engine performance and by continuing to pull collective pitch, the engine topped out, followed by the rotor RPM decreasing - which is known as "over pitching". At that stage the aircraft stops climbing (effectively the rotor blades are beginning to stall) and directional control in yaw decreases because the tail rotor is geared to the main rotor and suffers in the same way. Game over.
Had he approached the ridge at an acute angle, he could have left an escape route off to one side with known visual cues (because he had just flown past them). I used to teach my students never to fly to a ridge at 90 degrees.
Even in good visibility, if something goes wrong, such as engine failure in a single, or partial power loss in a twin, or even just a lack of sufficient power to make the angle of climb (such as in encountering a down-draught), you have a ninety degree turn to make to escape the rising ground and have to decide which way to go. Approaching a ridge at an acute angle, the escape turn need only be a small one - and you already know which way to turn.
Uplinker Just as an additional explanation. When a helicopter flies slow, it needs a lot of power. It is the same thing as a FW trying to hold altitude while going slower and slower. In a FW, once behind the bottom of the power curve, you can get in trouble by stalling the plane while using full power, therefore getting behind the power curve is something most pilots avoid. In a helicopter, we operate a lot in this region, it is normal, therefore power management is crucial. Many times you can't just "spool up"(the RPM does not vary a lot in a helicopter, but this is another longer subject) the engine. In this case he was heavy and slow, out of ground effect, it was hot and humid and his ship wasn't the strongest of the bunch (was an AB, no?). while he tried to turn left with his pedals, which would give him a bit more power by unloading the tail rotor, he did not have enough left to hover out of ground effect. He is not the first and will not be the last.
212Man,
Odd...I have never run out of control authority for main rotor control on any helicopter except for the French built designs.....and the BO and BK with roll/jyaw coupling in really steep turns.
I suppose the French just see things a bit differently.....thus no need for accumulators.
The Huey Cobra and the C and M models of Hueys had accumulators for collectives due to the 540 Rotor Systems.
The Alouette III used to have cyclic jams in extreme turbulence while mountain flying in Iran....used to think it was due to cavitation in the hydraulic system in strong down drafts as the sump contents stick to the top of the resevoir momentarily,.
Odd...I have never run out of control authority for main rotor control on any helicopter except for the French built designs.....and the BO and BK with roll/jyaw coupling in really steep turns.
I suppose the French just see things a bit differently.....thus no need for accumulators.
The Huey Cobra and the C and M models of Hueys had accumulators for collectives due to the 540 Rotor Systems.
The Alouette III used to have cyclic jams in extreme turbulence while mountain flying in Iran....used to think it was due to cavitation in the hydraulic system in strong down drafts as the sump contents stick to the top of the resevoir momentarily,.
Thank you Shy and Rotorbee, that is what I was asking - not that a guy screwed-up, we can see that - but the physics of what happened as applies to helicopters.
But I am still not quite there in my understanding. Suppose there been a helipad near the top of that ridge, are we saying that there would not have been enough power available to come to a hover and land on it? i.e. was the helicopter was above it's operational ceiling in terms of performance? meaning it could only stay aloft with forward speed, but did not have enough power at that altitude to hover?
Because he clears the ridge, and only crashes on the other side when the ground falls away. Was it because his Nr was reducing and bleeding energy as he approached the top of the ridge, and he barely got over it, by which time his Nr was too low to be recovered by engine torque?
In which case, once clear of the ridge could he have relaxed the collective and descended to follow the descending terrain to gain forward speed and lift?
(I am not advocating this as a sensible way to fly routinely !).
But I am still not quite there in my understanding. Suppose there been a helipad near the top of that ridge, are we saying that there would not have been enough power available to come to a hover and land on it? i.e. was the helicopter was above it's operational ceiling in terms of performance? meaning it could only stay aloft with forward speed, but did not have enough power at that altitude to hover?
Because he clears the ridge, and only crashes on the other side when the ground falls away. Was it because his Nr was reducing and bleeding energy as he approached the top of the ridge, and he barely got over it, by which time his Nr was too low to be recovered by engine torque?
In which case, once clear of the ridge could he have relaxed the collective and descended to follow the descending terrain to gain forward speed and lift?
(I am not advocating this as a sensible way to fly routinely !).