Learning from an NTSB final report.

[Vance]

There was a Cavalon (a two place side by side enclosed gyroplane) accident August of 2019 without serious injuries and the NTSB factual report has been released.

I try to learn from accident reports and this one unfortunately appears typical and in my opinion the particular model of gyroplane had little to do with the accident.

It helps me to know what to empathize with my clients before signing them off for their proficiency check ride and what to look for when giving a proficiency check ride.

The Cavalon had 242.9 hours on her.

This pilot had 76 hours flying a Cavalon and 31 hours as pilot in command of a Cavalon.

I suspect the accident pilot had been close to the edge for some time and stepped over the edge on this flight.

It appears to me the accident investigator did a particularly good job of finding out what the accident pilot was thinking and I feel that is helpful in understanding how to avoid an accident like this.

I have run what the accident pilot told the investigator through my flight instructor experience filter and included some of my thoughts.

From the pilot’s statement to the investigator about the takeoff procedure that didn’t work out in the 2015 Cavalon:

1. Start the main rotor with the pre-rotator. Get the engine RPM to 2000 and get the main rotor up to 200 RPM, then release the pre-rotator.

2. Pull the control stick back.

3. Increase the throttle to 30 inches of vacuum.

4. Accelerate to 43 to 44 miles per hour then throttle up to 35 inches of vacuum (full power).

5. Allow the control stick to float forward.

6. About 55 to 56 it takes off. He said it requires a little left stick because it tends to go right on takeoff because of torque forces.

7. Keep the gyroplane in ground effect until 56 to 57.

The accident investigator probed a little further and:

”When asked about taking off with a flat rotor he stated that if you did that you would not get the airstream to keep it [main rotor] rotating. He said that you could put it over on its side easy especially if you push the stick forward. When asked about not having the control stick full aft, beginning the takeoff roll and then pulling the stick back, he said that you don’t want to use too much aft control stick, you want to let it lift off by itself. He said that he tends to give it a little aft stick (1/2 inch) and that gets the nose off and it takes off just fine and its always worked fine for him. He said on the accident takeoff roll he had the stick forward and it was not taking off, so he just pulled a little aft stick and that is when it all happened. He said that it couldn’t have been more than a half an inch and it lifted off the ground. When asked about his flying history, he indicated that he received his Sports Pilot certificate in 2015. He has about 300 hours total with about 80 to 90 in the gyroplane”.

It is my observation from reading lots of accident report pilot’s statements that the accident pilot may be trying to impress the investigator with his knowledge of flying and avoid a 709 ride.

What is colloquially referred as a 709 ride is a re-examination of a pilot’s certificate by the FAA because the pilot was involved in an incident or accident that triggered some question about the pilot’s competence or ability to meet the qualifications of the certificates and/or ratings held.

In my experience if I ask the same questions of someone I am teaching I will get back much closer to what I have taught him or what is in the pilot’s operating handbook because he wants to move forward and he imagines parroting me or quoting the POH is the best way to do that.

I have received flight instruction from the accident pilot’s flight instructor and I feel confident in saying that 3 through 6 are not what the accident pilot was taught.

Pre-rotation and takeoff procedures from the POH for a 2015 AutoGyro Cavalon:

“4.8 Take-off Procedure

Check relative wind.

Maintain control stick in forward position with right hand.

Switch pneumatic mode selector to FLIGHT and return to brake with left hand.

Hold wheel brake without having locking pawl engaged.

While holding wheel brake adjust 2000 RPM with throttle Activate and hold pre-rotator.

Let pneumatic clutch fully engage (stabilization at about 110 rotor RPM).

If necessary release pre-rotator button momentarily and press again to maintain engine RPM within green arc, and prevent engine from stalling! Carefully increase throttle (~ 20 R-RPM/sec) to 200 R-RPM – max. 220 R-RPM.

Release pre-rotator button.

Gently move control stick fully aft (stick travel ~ 1 sec.).

In a strong headwind be prepared to stop movement before nose wheel rises! Release wheel brake with throttle unchanged.

Monitor rotor speed and adequately increase throttle to take-off power.

4.9 Take-off Run:

Check full power available for take-off. Otherwise, abort take-off.

Minimize lateral drift by applying appropriate lateral control stick input into cross wind direction

Maintain directional control i.e. runway alignment with sensitive pedal input.

When nose comes up allow nose wheel to float at about 10 – 15 cm above the runway by a balanced reduction of control stick back pressure Maintain attitude until speed increases and gyroplane lifts off (at around 50mph).

Allow gyroplane to build-up speed in ground effect.”

Words have meaning and it appears to me there is a substantial divergence between the accident pilot’s procedure and the pilot’s operating handbook.

 

[Vance]

Based on my assumption that the accident pilot was taught the correct procedure why would he makeup step 3 though 6?

3. Increase the throttle to 30 inches of vacuum.

To most people manifold pressure sounds more aviation that rpm. In my opinion it would be a misuse of the manifold pressure gage to try to manage low power setting rpm.

4. Accelerate to 43 to 44 miles per hour then throttle up to 35 inches of vacuum (full power).

This is appears to me to be fixed wing thinking that takeoff is all about speed. I suspect that was not what he was taught. In my opinion if a gyroplane is flown correctly she will lift off on her own at some combination of rotor rpm and indicated airspeed without the pilot pulling the cyclic back.

5. Allow the control stick to float forward.

This is the one I find particularly puzzling.

When I am teaching someone to take off I emphasize the aircraft’s response to the control inputs. I cannot think of a time during the takeoff roll letting the cyclic float forward would be appropriate.

If I understand the words correctly it appears to me trim would affect the floating.

It appears to me from the accident pilot’s description of the accident in the telephone interview that he did not follow his own procedures.

This appears to be a stop and go rather than an initial takeoff requiring using the pre-rotator. In my opinion the rotor rpm is still the point.

“In a telephone interview with the pilot, he said that on the day of the accident, he had been doing stop and go’s and had probably done three or four landings before the accident. He said that his rotor RPM was about 190 and he had intended to just do another stop and go. According to him, the gyroplane usually lifted off around 52 MPH, but on the accident takeoff roll, it was almost 60 MPH, and it still wasn’t lifting off. He said that he eased the stick back a bit and the gyroplane popped up, the tail went up, pitched up and yawed to the right. He heard a banging sound, and it immediately came down. When the banging sound occurred, the gyroplane’s nose was about 45 degrees to the right. It then rolled over on its left side and skidded along until it came to a stop. He said that it took about 3 to 4 seconds for all this to happen. Once it came to a stop, he did a quick assessment and he exited through the right door. He reiterated that he got the bang noise immediately as soon as the gyroplane left the ground. He suspected that it could have been the rotor. He said it was twisting to the right immediately afterward. He said as soon as it left the ground the nose went up and to the right, while he was giving it left stick as he always had. It came down and he did not have time to react with rudder or anything else. He mentioned the stabilizer being detached from the tail-shaft and he did not know how that happened.”

This has many of the elements of a blade sailing incident where a pilot has too much air speed for the rotor rpm and brings the cyclic back stalling the retreating blade and sailing the advancing blade which pushes the retreating blade into the empennage and/or propeller.

It is interesting to me from the above statement; the accident pilot appears to feel the cyclic controls yaw. I teach that once airborne the rudder controls yaw.

A flight instructor has to find a way to teach the takeoff procedure by the book, explain the why of each step so the learner will remember it and recognize when the learner is not getting it.

It is not uncommon for a learner when trying to relate things to their personal experience to imagine they understand something they don’t and make up procedures that are inappropriate.

I often ask my clients to teach me to takeoff as I have found it is a good way to identify weaknesses.

I have also experienced learners who can quote the book perfectly and then do something completely different when it comes time to takeoff.

The question for the flight instructor becomes; how do I identify and address these piloting short comings when the pilot may well be doing his best to hide them from me?

It is my observation that when a pilot doesn’t understand something or harbors inappropriate fantasies; it only gets worse and more imbedded over time.

I don’t know how much it cost to repair the aircraft; my guess would be somewhere north of $20,000.

These accidents affect our insurance rates so it is in our interest as gyroplane pilots to help people understand how to takeoff in a gyroplane.

I would love it if this post caused people to talk about taking off in a gyroplane and what can go wrong.

Taking off in a gyroplane is easy and yet somehow a third of gyroplane accidents are on the takeoff roll.

 

[WaspAir]

I had assumed that a Cavalon in the U.S. is most likely to have a fixed pitch prop to retain Sport Pilot eligibility, which would make a manifold pressure gauge somewhat unusual. Did this one have a controllable prop?

 

[Vance]

I had assumed that a Cavalon in the U.S. is most likely to have a fixed pitch prop to retain Sport Pilot eligibility, which would make a manifold pressure gauge somewhat unusual. Did this one have a controllable prop?

From the pictures it appears to be a ground adjustable propeller.

The manifold pressure is useful for determining power settings because of the turbo.

Using thirty inches of manifold pressure to determine the power setting to initiate the takeoff roll seems inappropriate to me and divergent from the POH.

 

[WaspAir]

OK, for monitoring boost. Thanks, Vance.

 

[PJB]

A detailed post Vance and agree with much of it. As it relates to this accident there are two stand outs. The first is he didn't even follow his own process, so now you can write a new list, a "correct" list, a POH list, whatever but if he doesn't follow it then that is just a mistake.

In my experience mistakes are more common if the process is more complex.

In my experience mistakes are more common if the person is less experienced.

We can decide how much of either apply here.

Yet this was not a regular take off accident. The pilot wasn't pre-rotating but doing stop and go landings using residual RRPM to effect the next take off. That is fraught with danger and this accident IMO is proof of those dangers. Principle amongst them is stick position, residual rotor thrust, RRPM and the rate of change to RRPM depending upon when you decide you are going to start the next take off.

If I start my take off roll having first pre-rotated to 200RRPM and then release the wheel brake I will get a different aircraft response than if I do a touch and go where the aircraft remains rolling and the RRPM is still up towards 300RRPM, and a different response again if the aircraft has stopped and the RRPM is at 250, or 200 [yet decaying] or 180 and decaying.... etc, etc.

I don't think that detracts from your post Vance but there is a lot to unpack and actually in this case the inexperienced pilot was trying to do something that while on the face of it seems very simple there is a lot going on and if not done consistently you get a very different reaction from the aircraft. Not necessarily the fault of Cavalon but actually those reactions are magnified in that aircraft.

 

[Abid]

Ok so a Stop and go
You land and come to a full stop. Rotor RPM goes down to 250 and decays further if you take your time. In his case down to 190. Stop and go should mean he starts with No forward roll.

If he is still rolling he is doing a touch and go.

Anyway, both still require to pull stick back and smoothly apply power and watch a trend in rotor rpm and balance and takeoff.
Is it different than that. Fundamentally still the same. If on a touch n go your are rolling too fast, it’s just bad execution and you need to let the aircraft slow down.

 

[PJB]

I agree Abid in principle, but you can do it, I can do it and yet some can't do it. This guy, the guy who crashed recently in the UK couldn't do it.

You have a lot of stick movements, aft to flare to land which is developed to come to a stop, then forward stick and some wheel brake, then aft stick to commence the next take off... great so far but if he is distracted slightly and his usual process meant he had 250RRPM meaning he did XYZ and now he had 190 and falling meaning his XYZ process pranged the aircraft. If he looked at the RRPM [which this pilot says he didn't - too busy faffing with the manifold pres.!] maybe it would be ok? No idea.

Many gyroplanes have been sacrificed on the touch and go alter - bit like the old spin training in fixed wings. Nothing is hard if you can do it, turns out this guy couldn't.

 

[Tyger]

During my primary instruction we did a LOT of touch and goes, and stop and goes. Sometimes my instructor would deliberately engage me in conversation after a stop, as the rotor rpm decayed, just to see what I would do when it was time to get going again.
He absolutely drilled it into my head to always check the rrpm. If it was under 200, he made sure I applied the throttle only gradually, with the stick all the way back, not giving it the full gas till the rotor was over that speed.

 

[Tyger]

I agree Abid in principle, but you can do it, I can do it and yet some can't do it. This guy, the guy who crashed recently in the UK couldn't do it.

I believe this is true of flying in general...
It really sounds to me like this pilot never actually understood some of the basic principles of flying gyroplanes.

 

[Vance]

A detailed post Vance and agree with much of it. As it relates to this accident there are two stand outs. The first is he didn't even follow his own process, so now you can write a new list, a "correct" list, a POH list, whatever but if he doesn't follow it then that is just a mistake.

In my experience mistakes are more common if the process is more complex.

In my experience mistakes are more common if the person is less experienced.

We can decide how much of either apply here.

Yet this was not a regular take off accident. The pilot wasn't pre-rotating but doing stop and go landings using residual RRPM to effect the next take off. That is fraught with danger and this accident IMO is proof of those dangers. Principle amongst them is stick position, residual rotor thrust, RRPM and the rate of change to RRPM depending upon when you decide you are going to start the next take off.

If I start my take off roll having first pre-rotated to 200RRPM and then release the wheel brake I will get a different aircraft response than if I do a touch and go where the aircraft remains rolling and the RRPM is still up towards 300RRPM, and a different response again if the aircraft has stopped and the RRPM is at 250, or 200 [yet decaying] or 180 and decaying.... etc, etc.

I don't think that detracts from your post Vance but there is a lot to unpack and actually in this case the inexperienced pilot was trying to do something that while on the face of it seems very simple there is a lot going on and if not done consistently you get a very different reaction from the aircraft. Not necessarily the fault of Cavalon but actually those reactions are magnified in that aircraft.

Thank your for your input Phil.

I like simple too and I can understand your desire for consistency.

I teach at an airport with an operating control tower and a 150 foot wide 8,004 foot long runway.

I typically request the option and practice stop and goes because it is less disruptive of traffic flow and on a windy day in a Cavalon it is easy to have the brakes fade on a taxi back.

I require the learner to be completely finished with the landing before commencing the takeoff roll carefully monitoring the rotor rpm. In a Cavalon if the rotor rpm has dropped below 200 we begin the pre-rotation process over again from a full stop with the cyclic full forward.

 

[Vance]

During my primary instruction we did a LOT of touch and goes, and stop and goes. Sometimes my instructor would deliberately engage me in conversation after a stop, as the rotor rpm decayed, just to see what I would do when it was time to get going again.
He absolutely drilled it into my head to always check the rrpm. If it was under 200, he made sure I applied the throttle only gradually, with the stick all the way back, not giving it the full gas till the rotor was over that speed.

Thank you for sharing your experience.

I find enough to distract my clients without doing it intentionally.

Intentional distractions appear to have worked for you.

I generally save intentional distractions for the check ride.

In a Cavalon if the rotor rpm has dropped below 200 we start the pre-rotation process over again.

 

[Vance]

Ok so a Stop and go
You land and come to a full stop. Rotor RPM goes down to 250 and decays further if you take your time. In his case down to 190. Stop and go should mean he starts with No forward roll.

If he is still rolling he is doing a touch and go.

Anyway, both still require to pull stick back and smoothly apply power and watch a trend in rotor rpm and balance and takeoff.
Is it different than that. Fundamentally still the same. If on a touch n go your are rolling too fast, it’s just bad execution and you need to let the aircraft slow down.

I can see both sides of this and for me it depends on the pilot under instruction.

People seem to learn in many different ways and approach aviation in their own unique style; I try to adjust to that.

 

[Abid]

I can see both sides of this and for me it depends on the pilot under instruction.

People seem to learn in many different ways and approach aviation in their own unique style; I try to adjust to that.

If you touch down a gyroplane at 20 mph, I am not adjusting to you. You have to adjust to what I am saying. Just sayin.

 

[Vance]

If you touch down a gyroplane at 20 mph, I am not adjusting to you. You have to adjust to what I am saying. Just sayin.

I too have my standards Abid.

 

[Abid]

I agree Abid in principle, but you can do it, I can do it and yet some can't do it. This guy, the guy who crashed recently in the UK couldn't do it.

You have a lot of stick movements, aft to flare to land which is developed to come to a stop, then forward stick and some wheel brake, then aft stick to commence the next take off... great so far but if he is distracted slightly and his usual process meant he had 250RRPM meaning he did XYZ and now he had 190 and falling meaning his XYZ process pranged the aircraft. If he looked at the RRPM [which this pilot says he didn't - too busy faffing with the manifold pres.!] maybe it would be ok? No idea.

Many gyroplanes have been sacrificed on the touch and go alter - bit like the old spin training in fixed wings. Nothing is hard if you can do it, turns out this guy couldn't.

If I can do it, anyone can do it. I am not a great natural pilot. I learn things in very systematic ways and develop flows that work for me to ingrain procedures into natural habits and mainly I try and understand conceptually what is happening so all these things make sense because that makes it much easier. I wish I was a great natural pilot kind of guy but I am not.

 

[chrisk]

I've yet to hear what everyone thinks the pilot did incorrectly. Maybe it is obvious to all that he didn't hold the stick back until the front wheel came off the ground. This means the disk angle was too shallow as the gyro was accelerating in the take off roll. And the shallow angle prevented the rotor from coming up to flying rpm. When he came back on the stick, he experienced blade flap due to the low rotor RPM and high forward speed. In my opinion, the advancement of the throttle to 30 inches, and then later to 35 inches was not a contributing factor.

As to what you can teach your student.

• Start with stick back and don't move it forward until the front wheel comes up (yes the pilot didn't do this, he released back pressure instead)
• Monitor rotor RPM. Abort the take off if it is not where it should be.
• If you are well into your takeoff roll and don't have the front wheel up, don't try to fix it by moving the stick back. Fix it by aborting the take off.

 

[Tyger]

As to what you can teach your student.

• Start with stick back and don't move it forward until the front wheel comes up (yes the pilot didn't do this, he released back pressure instead)
• Monitor rotor RPM. Abort the take off if it is not where it should be.
• If you are well into your takeoff roll and don't have the front wheel up, don't try to fix it by moving the stick back. Fix it by aborting the take off.

Agreed. But it seems that there are some folks who have not learned (or been taught) how to abort a gyroplane takeoff...

 

[PJB]

I've yet to hear what everyone thinks the pilot did incorrectly.

He didn't follow his own process [from the NTSB report]. Had he the aircraft wouldn't have been pranged. I also think that his relative inexperience and the task of stop and go's created a higher risk environment.

 

[PJB]

Aside from this its coming up to the 2 year anniversary of the last accident, anyone know why that hasn't been reported upon yet? Are there some relevant points of discussion or is it just the usual slow reporting.