Hihover......if you have free access to a Sim....and care not to utilize its great potential for learning and exploration of how a helicopter reacts to unusual events....please understand I find that attitude discouraging.
You have a golden opportunity and seem to be throwing it away. Take the Sim out of motion....and run the scenario that way....so you only have the Visual and Instruments operating while the Sim sets happily on the blocks. |
Originally Posted by 212man
(Post 10322504)
How do we know that it was?
The helicopter then began a climb on a rearward flight path2 while maintaining a northerly heading. Gear retraction started as it passed through a height of approximately 320 ft. The climb then paused. Heading changes consistent with the direction of pedal movements were recorded initially, then the helicopter entered an increasing right yaw contrary to the pilot’s left pedal command. The helicopter reached a radio height3 of approximately 430 ft before descending with a high rotation rate. |
SAS....:):):) I have a job. Please feel free to be discouraged by me maintaining my employment. :):) When I have time I will have another look.
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Originally Posted by DOUBLE BOGEY
(Post 10322554)
212Man from AAIB Special Bulletin:
The helicopter then began a climb on a rearward flight path2 while maintaining a northerly heading. Gear retraction started as it passed through a height of approximately 320 ft. The climb then paused. Heading changes consistent with the direction of pedal movements were recorded initially, then the helicopter entered an increasing right yaw contrary to the pilot’s left pedal command. The helicopter reached a radio height3 of approximately 430 ft before descending with a high rotation rate. Earlier a poster, who would appear to be familiar with the type, posted this: The TDP is 115ft + the height of the obstacle in your takeoff path so I’d guess a minimum of 250-300ft. |
Chop, take-off profiles are designed to give us the best chance when dealing with an engine failure, and they actually work very well if you stick to the profile when you lose an engine. Sadly, it would be impossible to write a similar profile for the catastrophic tail rotor event because control is effectively lost. It is not lost when an engine fails.
DB. Not sure why the gear was retracted, I haven't flown the 169 and know very little about it. In truth I don't believe it would have made any difference. Clearly, if he had suffered an engine failure before TDP he would have had to be quite slick with the gear but from that height I'm sure he felt he had plenty time to put it down again if required. Personally, I raise the gear when it is of no further use to me (rather than 200 feet on climb out). I normally operate from a 10,000 ft taxiway so I have the option to reject for quite a while. |
Originally Posted by 212man
(Post 10322588)
Yes, I've read the report (in fact it was me that posted the link here first). But, where in that paragraph does it state what the TDP height was?
I think though, that the salient point is should retractable landing gear be raised prior to achieving a sensible amount of forward airspeed and height. Obviously prior to TDP the gear should of course remain available for a reject. In big helicopter world, as you know, we generally do this at Vy+200 feet. More to avoid distraction between VTOSS and Vy and often to conform to a critical performance profile. However, if we accept that the landing gear is able to absorb some considerable energy in a high ROD touchdown, then maybe the Vy+200 feet (both conditions having to be met), is a good compromise should the RFM not specify for the operating conditions. I guess what I am really alluding to is would the outcome in this instance have been improved if the gear remained down to absorb the initial energy at impact. |
I guess what I am really alluding to is would the outcome in this instance have been improved if the gear remained down to absorb the initial energy at impact |
Originally Posted by Non-PC Plod
(Post 10322510)
Hmm.... Be interesting to know what regulation you think would ensure a safe profile to get out of a football stadium with a tail rotor failure! Somehow ,I dont think you can avoid exposure to a low speed/high torque environment.
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Originally Posted by chopjock
(Post 10322615)
I can't help but think a diagonal forward acceleration from the far downwind corner and a zoom climb at the upwind corner would have resulted in less exposure time and less stress to the tail rotor. This obviously puts more reliance on the engines, but they are very reliable these days and there are two of them!
Having said that, the fact that this, and other TR malfunctions have occurred leading to loss of the aircraft and sometimes occupants, at low speeds means you are making an argument. How does the likelihood of a TR event compare to an OEI before TDP? |
Chopjock,
As always you think you know better than those who actually do the job. However, most of us tend to operate the aircraft in accordance with the manufacturer's certificated performance procedures, even those of us not operating for public transport (where it is usually mandatory). It is sometimes a condition of the aircraft insurer (and therefore a requirement / condition of maintaining one's employment status with the operator) and it is always a condition of a CAA congested area written permission. |
Originally Posted by 212man
(Post 10322609)
Yes, I agree with you that even if they had reached TDP, the logic behind early retraction is not clear
Cheers TeeS |
Originally Posted by ShyTorque
(Post 10322633)
Chopjock,
As always you think you know better than those who actually do the job. However, most of us tend to operate the aircraft in accordance with the manufacturer's certificated performance procedures, even those of us not operating for public transport (where it is usually mandatory). It is sometimes a condition of the aircraft insurer (and therefore a requirement / condition of maintaining one's employment status with the operator) and it is always a condition of a CAA congested area written permission. And they were put in that position by the regulations in the name of safety... |
Chopjock, you are the ultimate laxative.
You continue to put forward your ridiculous views in the face of logic and weight of informed opinion against you. It would not surprise me if you were the twin (or alter ego) of the other fool on this board. Jim |
Now there is a thought......ONLY two Fools in this Forum!:D
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Originally Posted by SASless
(Post 10322653)
Now there is a thought......ONLY two Fools in this Forum!:D
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Originally Posted by DOUBLE BOGEY
(Post 10322631)
Chopjock, the profile you propose would require reject distance available if the helicopter is above the OEI-IGE Hover Mass. You would also need to prove you could clear the stadium OEI after TDP on the remaining engine. Its really difficult to make this work when the distance available are so short. That's why the Rearwards Profile (VTOL Helipad) was conceived. To overcome these issues.
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Originally Posted by TeeS
(Post 10322643)
Hi 212man, it is a long time since I flew retractable undercarriage aircraft but I always thought/assumed that the gear was retracted as soon as possible after TDP in order to minimise drag during the acceleration to Vtoss/Vy, I do wonder whether this was another hang over from fixed wing A/C where the target speeds are higher and so the drag had a bigger influence. Obviously those operating single pilot might feel there would be more important considerations during a busy stage of flight!
Cheers TeeS and less stress to the tail rotor |
Hi Chopjock, so you have backed your helicopter into the corner, accelerated as fast as possible towards the opposite corner (135m away according to Google Earth and that might just allow you to get to 25-30kts before you hit the far stands) and then 'zoom climbed' at a moment when you guess that your angle of climb will just avoid the stadium roof. Thankfully your one engine (one of my two engines) hasn't stopped because the engines are rather reliable, the climb continues until you get to the top of the stadium roof whereupon you continue an acceleration/climb to a suitable height. If at any time an engine stops (except in the first few seconds of acceleration or on reaching a safe height), the tail rotor quits its job, the rotor head lets go or you just overestimate your guess at what climb angle you were going to achieve, you stand a good chance of killing your passengers. How on earth can you argue that you have reduced any exposure times!!
Cheers TeeS |
Chopjock, don't think that the exposure to TR failure poor outcomes is restricted to zero speed hovering. TR Malfunction risks are present throughout the envelope and decrease significantly with speeds above Vy, However, in a twin, TR drive failure anywhere in the envelope turns you effectively into a SEH as an autorotation is generally required. Unless you have a Fenestron behind you whereby your options are significantly increased.
To illustrate my rather awkward point. If we all agreed to depart in accordance with your suggestion (Lets call it the "Corner" profile), losing the TR control or drive anytime in the first 70 knots would see you in a smoking heap. Up to 100 kts in the climb out your arse would be eating the seat cushion and the prospects of survival still 50/50. There are no easy alternatives. That's why others on this thread (and you have managed to stimulate JimL into a frenzy), think you somewhat lacking in the old common sense department. However, try not to get defensive and think carefully about what I have written. This is nothing new. TR Malfunctions and Drive Failures present limited prospects of success wherever they occur. |
TeeS
How on earth can you argue that you have reduced any exposure times!! |
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