Receive Good Training Part 3

[Mikemv]

As a Follow up to Parts 1 & 2, 4 different scenarios of engine failure at 40kts & 100' were listed.

1. was in level flight

2. was in a climb

3. was in a descent

4. was in autorotation

 

All of these are the same numerically but different aerodynamically.

The question was asked, which of these scenarios would be in the HV Shaded area?

 

Opinions/answers varied. Thanks to those that participated by answering!

 

HV discussion from C&E Seminar.

 

We look at the HV Diagram and see the Altitude on the left side and Airspeed along the bottom. Then there is the shaded area which indicates the conditions where an autorotation may not be successful.

 

What is not readily apparent and discussed/explained is that there is another element of time. Yes time, time to achieve an aerodynamic steady state autorotation. Rotor RPM is stabilized and rate of descent is constant at a given airspeed and in trim.

 

The question was asked about aerodynamic transitions upon engine failure? The answer is three fold: 1. Reversing the Air flow, 2. Decreasing the Angle of Attack to a tolerable level, and 3. Regaining rotor RPM & Stabilizing Rate of Descent

 

#1 happens even if we do not lower the collective (but we must of course)

#2 happens when we lower the collective (rapidly)

#3 happens some time later (Approx. 3-5 secs. and depends on attitude stabilization and banking and trim conditions)

 

The 3 elements that control where the Rotor RPM will stabilize are: DA, GW & pitch links

 

It should be come clear that from 40' there is no time for the rotor rpm to stabilize and attitude changes will only lengthen the time which is already too short at about 7-8 seconds.

 

This data comes from the old AC61-13B, pg. 67 for those of you that think I make this stuff up. Unfortunately it was not carried forward into the Rotorcraft Flying Handbook when it was updated. I know that this is not taught/discussed in most ground school or flight school curriculums. Not your fault!

 

I hope this info brings you some considerations on what to do when the engine quits in scenarios that are different than the training environment of 60/65kts and 500/700'.

 

Be Safe,

 

mike

Edited December 4, 2010 by Mikemv

[Goldy]

Mike, all good stuff to remember. You might also mention that when developing the HV curve, the test pilot is required to delay lowering collective for one full second. While that doesnt sound like a long time..well, I'm sure it feels like an eternity watching your rotor rpm drooping.

 

Early recognition of an engine failure could result in recoveries better than shown in the published HV curve. Of course, the opposite is true. Late recognition and reaction could result in failures and crashes even when operating well outside the curve.

 

Like anything, it is a guideline and not an absolute. Also, the curve is established by demonstrating several key points along the way...not by demonstrating each and every combination of airspeed/altitude.

 

There is no advantage to a manufacturer to narrow the size of the HV curve. In fact, just the opposite is true. Just compare an R66 HV to an R44 HV to see what I mean. In reality, the R66 has way more inertia in an auto, yet the curve is a bit higher/wider compared to the 44.

[Mikemv]

Goldy, thanks. All good info. I did not mention this as I was addressing items in Parts 1 & 2 of Receiving Good Training treads. My discussion during "C&E Seminars" includes what you mentioned for sure!

 

Also, note that the time delay for lowering the collective is only in the upper part where in theory pilots may be distracted doing something else. In the lower(take off) portion it is assumed that there hands are on the collective controlling power during the climb and therefore no delay. We can see that the 3 aerodynamic transitions have NO time to be accomplished during the lower take off portion and so it is most critical.

 

Mike

[Gary DeWitt]

My recollection was that there is a one-second delay in the lower part and a two-second delay in the upper part.

 

That contradicts what you both said, however you both contradict each other. Can anybody quote a source definitively stating the answer?

[Mikemv]

Gary,

I had it wrong!

I went from memory and was incorrect.

You stated it correctly as 1 second in lower part and 2 seconds in upper part.

 

Thanks for posting good info for us all!

 

Mike

[ADRidge]

You raise some good points Mike. I had the opportunity about a month before Heli-Expo to spend a good amount of time doing some advanced autos and other maneuvers with a rather experienced ag pilot/CFI, and I have to say... actually doing an auto at 150' at 40 knots (as low and slow as either of us really wanted to go in a training environment) was intense, to say the least.

 

I'm not skittish of helicopters at all, but I will say that in that flight profile, your auto and flare really turns into one big combination of movements, and I really and truly hope I never have to do that for real.

 

As far as training goes, I really wish I'd had more emphasis on aerodynamics as a PPL/CPL candidate. I'm getting more in-depth coverage now that I'm working on my CFI, but sometimes it feels like I'm behind the curve. Sad thing is, I know it's not just me.

[iChris]

My recollection was that there is a one-second delay in the lower part and a two-second delay in the upper part.

 

That contradicts what you both said, however you both contradict each other. Can anybody quote a source definitively stating the answer?

 

One second delay in the upper half and no delay in the lower half. Mike had it right the first time, but second guest himself. Three sources below:

1. AC 27-1B (pgB40-B41)

6 (i) High Hover. A stabilized out-of-ground-effect (OGE) hover condition prior to powerfailure is essential. A minimum1-second time delay between power failure and initial control actuation isutilized.

 

6 (ii) Low Hover. From the low hover position there is no flare capability and little timefor collective reaction. No timedelay is applied other than normal pilot reaction.

 

6 (iii) Takeoff Corridor. Normal pilot reaction is applied when the engine is madeinoperative. At low speeds,collective may be lowered quickly to retain RPM and minimize the time betweenpower failure and ground contact.

 

2. Shawn Coyle; Cyclic &Collective, So What's Missing about the HV Curve? pg 338

3.

Edited December 5, 2010 by iChris

[Mikemv]

Chris, thanks for posting documented info as you always do.

 

My first response to Steve (Goldy) was from memory of what Randy Rowles taught during an CFI auto/intervention class that us FAASTeam Reps put on before Heli-Success.

 

My second and now shown incorrect post was from copter.com that I hastily Googled! I guess that shows what that site is putting out.

 

Thanks again Chris!!!!

 

Mike

[StanFoster]

Mike- Let me say how much I really respect you bringing this HV or near HV curve scenarios to the forum. I mentioned that I personally feel that maybe my experience level in that real nasty situation I got myself into, only allowed me to pull off a run on landing on a sod runway. I have studied and studied all you have presented, and appreciate your concern and your tact fullness towards me trying to educate me to a higher level. You have to realize that here I was caught in a moment in time where at the least my helicopter was likely to receive serious damage, and I took actions that my skill level at that time made me go at it the way I did. My self critiquing attitude I have that constantly tries to better myself, agrees with your assessment. My normal autos always found me at proper airspeed, engine out, drop collective, give it some backstick, stabilize rotot rpm's, airspeed, ride her down to say 40 feet, flare off as much airspeed as possible while pulling some collective, level the skids, pull collective and land at o to minimal groundspeed. My moment in time in my flameout found me with not enough time to do all the above, and I omitted the hard flare at the end, but just leveled the skids and ran her on.

I will be diligently practicing these closer and closer to the real scenario I found myself in. I know my way would not have worked had I had rough terrain. Again Mike, I very much appreciate your concern trying to make me a better helicopter pilot. I assure you I am very much more improved as far as preventing getting into this scenario ever again, but I want to acquire the skills to land at as slow a forward speed as my helicopter is capable of. Stan- living and learning!

Edited December 5, 2010 by StanFoster

[Mikemv]

Dear Stan, first "God Bless You"! I am glad you got something out of all of this but it truly was NOT directed towards you. You jumped right in to discussions/postings and kicked elements & things around some.

 

Your event and video DID prompted me to post the 4 different scenarios to assess pilots feedback of how they would handle the situations. Many of the responses showed that pilots did not consider finding themselves in one of the 4 scenarios and what they would do. Others responded like they were in a training pattern with their CFIs. This is all good as it stimulated thoughts and discussion which was my original purpose for posting!

 

The areas of HV and aerodynamic transitions has been identified by me as missing or misunderstood in pilot training. It is included with many other items in my "C&E Seminar". (C=Clarification, E=Enhancement of Aeronatical Knowledge)

 

One area of discussion in my Sem. is called "the Experience Bank". It is the sum total of all ground school, discussions, internet info, flight training, and flight experiences that one accumulates. It is what we have to draw from when something arises and this does not necessarily have to be an emergency. It could just be a new situation where we apply our judgement.

 

I am willing to help anyone with info that requests it. I have posted my e-mail for direct contact if someone chooses. mikefranz@embarqmail.com Stan, you also have my phone number from the first PM I sent you.

 

Everyone be safe,

 

Mike

[StanFoster]

Dear Stan, first "God Bless You"! I am glad you got something out of all of this but it truly was NOT directed towards you. You jumped right in to discussions/postings and kicked elements & things around some.

 

Your event and video DID prompted me to post the 4 different scenarios to assess pilots feedback of how they would handle the situations. Many of the responses showed that pilots did not consider finding themselves in one of the 4 scenarios and what they would do. Others responded like they were in a training pattern with their CFIs. This is all good as it stimulated thoughts and discussion which was my original purpose for posting!

 

The areas of HV and aerodynamic transitions has been identified by me as missing or misunderstood in pilot training. It is included with many other items in my "C&E Seminar". (C=Clarification, E=Enhancement of Aeronatical Knowledge)

 

One area of discussion in my Sem. is called "the Experience Bank". It is the sum total of all ground school, discussions, internet info, flight training, and flight experiences that one accumulates. It is what we have to draw from when something arises and this does not necessarily have to be an emergency. It could just be a new situation where we apply our judgement.

 

I am willing to help anyone with info that requests it. I have posted my e-mail for direct contact if someone chooses. mikefranz@embarqmail.com Stan, you also have my phone number from the first PM I sent you.

 

Everyone be safe,

 

Mike

Mike- Your e-mail with your phone number must have gone into my spam filter, or I deleted it by accident. Could you resend my your phone number to my e-mail at strbldr@yahoo.com and the best time to call you. Thanks. Stan