Flyaway manoeuvre
Thread Starter
I knew the 139 constantly reviewed the performance data and gave you a min height for hovering that would allow a flyaway - does the S-92 do the same thing?
The Sea King obviously doesn't have any 'drop-down' data in the ODM to calculate height loss whereas the Lynx does have graphs for predicted height loss in the hover (into wind). We do have the ability to hover higher to maintain a flyaway but the assessment of performance is still only based on hover torque even though the proximity to ETL makes a huge difference to the height loss during the flyaway.
Junior pilots will always want a simple 'one-stop shop' answer to flyaway or not flyaway but there are so many variables that it is impossible to shortcut experience. For example, tonight we were hovering at 125' alongside a large car carrying vessel - we were about 100 degrees out of wind and the boat was doing 15 kts - our airspeed across the disc was next to zero and when the HP tried a practice flyaway we had to throw it away so as to avoid the water. He flew a normal profile of 1 or 2 degrees nose down as he would into wind and it didn't work - when we tried it again with 7 or 8 degrees we made ETL and flew away with relative ease.
The Sea King obviously doesn't have any 'drop-down' data in the ODM to calculate height loss whereas the Lynx does have graphs for predicted height loss in the hover (into wind). We do have the ability to hover higher to maintain a flyaway but the assessment of performance is still only based on hover torque even though the proximity to ETL makes a huge difference to the height loss during the flyaway.
Junior pilots will always want a simple 'one-stop shop' answer to flyaway or not flyaway but there are so many variables that it is impossible to shortcut experience. For example, tonight we were hovering at 125' alongside a large car carrying vessel - we were about 100 degrees out of wind and the boat was doing 15 kts - our airspeed across the disc was next to zero and when the HP tried a practice flyaway we had to throw it away so as to avoid the water. He flew a normal profile of 1 or 2 degrees nose down as he would into wind and it didn't work - when we tried it again with 7 or 8 degrees we made ETL and flew away with relative ease.
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Trial and error
Hi Crabb
When I got to the 412 it had a similar issue with the flyaway technique. It too required a 20 degree change - note it used the phrase "up to". I tried the Sea King standard min height loss tech Kaye and it appeared to work well. I used the same technique described already for students by going to half power twin engine and trying both techniques to show the difference. It was simply stunning the difference in height loss and effect it could have on a crew. I had the chance to go to the Bell factory and discuss this with the TP's. They referred me back to the phrase "up to". that said they then produced a supplement to the RFm that we hadn't had as well! Long story and not a good one!
I have seen the same remarks with regard to the EC225 as well regarding fly away - it wAs demonstrated by the TP's in the Sim.
So, my gut feel says if the RFm says select an attitude then some clever people have checked it and you are probably not wise to mess about. If it says "up to" then perhaps ther is scope to gain experience before the worst happens and you need it for real.
When I got to the 412 it had a similar issue with the flyaway technique. It too required a 20 degree change - note it used the phrase "up to". I tried the Sea King standard min height loss tech Kaye and it appeared to work well. I used the same technique described already for students by going to half power twin engine and trying both techniques to show the difference. It was simply stunning the difference in height loss and effect it could have on a crew. I had the chance to go to the Bell factory and discuss this with the TP's. They referred me back to the phrase "up to". that said they then produced a supplement to the RFm that we hadn't had as well! Long story and not a good one!
I have seen the same remarks with regard to the EC225 as well regarding fly away - it wAs demonstrated by the TP's in the Sim.
So, my gut feel says if the RFm says select an attitude then some clever people have checked it and you are probably not wise to mess about. If it says "up to" then perhaps ther is scope to gain experience before the worst happens and you need it for real.
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Wouldn't it be nice to have a good low airspeed indicator so that you could know (within 2-3 knots) what the actual airspeed through the disk was - that way you could know with a good deal more certainty how much nose down to use?
We have the technology, we just lack the political will....
We have the technology, we just lack the political will....
Thread Starter
SARREMF - yes, the only known engine fail at SARTU on the 412 would have been a ditching if the QHI had used 20 degrees nose-down. As it was he used the Sea King technique and flew away despite being theoretically committed.
Shawn - yes, that would solve a lot of issues - what technology exists that isn't being used or is it just better designed and positioned pitot tubes we need?
At least it seems that disc loading and blade design don't seem to be factors, it is simply the case that a 'one-size-fits-all' technique for dealing with a single engine fail in the hover doesn't exist and, whilst guidance in the RFM/ODM is one thing, there is no substitute for experience and practise.
Shawn - yes, that would solve a lot of issues - what technology exists that isn't being used or is it just better designed and positioned pitot tubes we need?
At least it seems that disc loading and blade design don't seem to be factors, it is simply the case that a 'one-size-fits-all' technique for dealing with a single engine fail in the hover doesn't exist and, whilst guidance in the RFM/ODM is one thing, there is no substitute for experience and practise.
Our EC135 FLM doesn't give any guidance on the amount of nosedown. It just says: Airspeed - increase if possible. It's quite a benign occurance for us, even 90 degs out of wind and at our typical weights. Pull to 30 second power and we can fly away without any height loss.
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MG, that is very impressive OEI performance.
How much are you below gross weight to give 'a Hover, no loss of height fly-away' on OEI?
Does the EC135 also have a CAT A Helipad take off profile that allows take off at gross weight AND no drop-down with engine failure at TDP?
FLI
How much are you below gross weight to give 'a Hover, no loss of height fly-away' on OEI?
Does the EC135 also have a CAT A Helipad take off profile that allows take off at gross weight AND no drop-down with engine failure at TDP?
FLI
Only done the flyaways during OPCs when our weight is typically around 2600kgs(max 2910), so probably better performance that when at the max.
Yes, we have helipad capabilty at MAUM(+17 C at S/L). The TDP for Cat A(Perf 1) is 120ft, and, again at OPC weights, there is very little height loss. Even so we can flyaway without having to use the 30 second rating, so it's possible that using that at MAUM the performance could be similar. Then again, maybe not.
Yes, we have helipad capabilty at MAUM(+17 C at S/L). The TDP for Cat A(Perf 1) is 120ft, and, again at OPC weights, there is very little height loss. Even so we can flyaway without having to use the 30 second rating, so it's possible that using that at MAUM the performance could be similar. Then again, maybe not.
I would have assumed that to carry out winching you would have OEI/HOGE performance. Then again it would depend on the classification of the operation.
EC 135 has OEI/HOGE published data of course. Simple rule of thumb is that most times 128% Q (depending on model - quoting P2+ here) is available at 30 sec OEI rating. Therefore if torque required to hover is less than 2 x 64% on the digital readout (Not FLI value) = no brainer. However at values above that the following is published as an "Operational Tip".
Section 10 Manufacturers data (NOT APPROVED)
10-3 Rev. 2
HEIGHT LOSS AFTER ENGINE FAILURE / HOVER PERFORMANCE
10.2.1 i.e. a safe forced landing cannot be accomplished, or for overwater operations. This information is NOT applicable for operation requiring OEI-HOGE performance.
10.2.3 Flight procedure after single engine failure in hover (HOGE)
Procedure
1. Attitude - Nosedown ~ -20°
Under wind conditions the following values are recommended:
Up to 20 kt -20°
~ 30 kt -10°
above 40 kt 0°
2. Collective lever - adjust to 30 sec. Power
3. Attitude - Adjust to near level attitude while accelerating to V TOSS = 40 KIAS and initiate climb.
Height loss chart would indicate via extrapolation the following for :
PA 0'
At least 12' in all cases but at the following weights and temp no more:
2500 kg 46 ℃
2600 kg 36 ℃
2700 kg 0 ℃
STD day at 2910 kg MAUM you would lose ~ 75'
10 knots of wind would reduce that by about 25' = 50'
NOTE: UNAPPROVED DATA
EC 135 has OEI/HOGE published data of course. Simple rule of thumb is that most times 128% Q (depending on model - quoting P2+ here) is available at 30 sec OEI rating. Therefore if torque required to hover is less than 2 x 64% on the digital readout (Not FLI value) = no brainer. However at values above that the following is published as an "Operational Tip".
Section 10 Manufacturers data (NOT APPROVED)
10-3 Rev. 2
HEIGHT LOSS AFTER ENGINE FAILURE / HOVER PERFORMANCE
10.2.1 i.e. a safe forced landing cannot be accomplished, or for overwater operations. This information is NOT applicable for operation requiring OEI-HOGE performance.
10.2.3 Flight procedure after single engine failure in hover (HOGE)
Procedure
1. Attitude - Nosedown ~ -20°
Under wind conditions the following values are recommended:
Up to 20 kt -20°
~ 30 kt -10°
above 40 kt 0°
2. Collective lever - adjust to 30 sec. Power
3. Attitude - Adjust to near level attitude while accelerating to V TOSS = 40 KIAS and initiate climb.
Height loss chart would indicate via extrapolation the following for :
PA 0'
At least 12' in all cases but at the following weights and temp no more:
2500 kg 46 ℃
2600 kg 36 ℃
2700 kg 0 ℃
STD day at 2910 kg MAUM you would lose ~ 75'
10 knots of wind would reduce that by about 25' = 50'
NOTE: UNAPPROVED DATA
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In a night hoisting without beeing able to hover OEI we almost always breif a landing (ditching) in case of engine failure. This because it is the safest way.
To think that you would react quick enough and fly away according to all the theorethical values in the FM without hitting the water is abit overconfident.
Safety first...make a controled ditching...survive, get a new chopper.
To think that you would react quick enough and fly away according to all the theorethical values in the FM without hitting the water is abit overconfident.
Safety first...make a controled ditching...survive, get a new chopper.
Safety first...make a controled ditching...survive, get a new chopper.
Thread Starter
Oden, we make a call based on hover torque - either safe single engine, flyaway or committed but there will always be marginal cases and carrying out a 'controlled' ditching in a high sea state might not be that safe.
You make a good point crab; an uninformed decision either way will be wrong. Ditching when you have sufficient performance for a flyaway is a bad decision.
The only way to deal with this is to know: the performance in hand; the optimum rotation; and the likely drop down. It is only the marginal cases where a decision will be difficult.
Fortunately, high seas are normally associated with high winds - the aviators saviour.
Jim
The only way to deal with this is to know: the performance in hand; the optimum rotation; and the likely drop down. It is only the marginal cases where a decision will be difficult.
Fortunately, high seas are normally associated with high winds - the aviators saviour.
Jim
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Go or not to go......
Maybe the decider is the pilots awareness of his reaction time. If you are really on the ball when a donkey stops and the right answer is -20 and go then have a shot. If, on the other hand you were caught flat footed then an extreme nose down is probably not going to be a good investment.
Rehearsing in the sim can be a great way forward but we need more assurances about the fidelity of the sim in a regime not necessarily covered during certification.
G.
Rehearsing in the sim can be a great way forward but we need more assurances about the fidelity of the sim in a regime not necessarily covered during certification.
G.
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The decision does not have to be final, either.
I know a couple of RN guys that had a single engine failure on take-off from a carrier.
Nr drooped well below 91% so they decided to land on the water. During the flare the Nr recovered enough to continue flying at very very low level in ground effect until speed/Nr recovered back to reasonable values.
I know a couple of RN guys that had a single engine failure on take-off from a carrier.
Nr drooped well below 91% so they decided to land on the water. During the flare the Nr recovered enough to continue flying at very very low level in ground effect until speed/Nr recovered back to reasonable values.
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Teaching flyaways from 50ft in a Lynx several years ago, the conditions were such that if slightly more than 15deg nose down was selected, the rate of descent built up and we had to run on; any less and the aircraft failed to accelerate quickly enough and we ran out of height, again necessitating a run on.
Only by selecting and holding 15deg were we able to fly away. This demonstrated to me the importance of carrying out the recommended technique.
Only by selecting and holding 15deg were we able to fly away. This demonstrated to me the importance of carrying out the recommended technique.
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The AS332L2 SAR Support allows for you to calculate your weight for the 30sec rating and then if required it is a normal transition into forward flight. If you're too heavy then you can use the 15deg nose down method. That is quite exciting.
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Having been HP for a bent SK while practicing OEI flyaway - way back in about 1985 when the QHIs hadn't worked out properly how to simulate using manual throttles - I can confirm that 20 deg ND in a SK is likely to lead rapidly to the scene of the incident. Less ND, while not necessarily changing the chance of a flyout, would have given us better attitude / VV at impact and would probably have resulted in less damage.
Also, the SK procedures and numbers as used in the RAF are designed to cope with the IFR autohover case. There is, I believe, an inbuilt assumption that large attitude changes at low level are likely to lead to (Un) CFIT, and thus the numbers are designed to get you gently out of an inherently recoverable situation without losing control ie it's not just about power margins.
Sven
Gently eradicating 33 years experience with red wine
Also, the SK procedures and numbers as used in the RAF are designed to cope with the IFR autohover case. There is, I believe, an inbuilt assumption that large attitude changes at low level are likely to lead to (Un) CFIT, and thus the numbers are designed to get you gently out of an inherently recoverable situation without losing control ie it's not just about power margins.
Sven
Gently eradicating 33 years experience with red wine
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I guess what we've agreed on is that different types, environments, etc need a different response. Some with a large nose down, others not. But then we probably knew that, as even on the same type you may need two different techniques on different days.
Fly safe!
Fly safe!