CSU Endorsement

[Guest pelorus32]

I took the opportunity to do a CSU endorsement on the Rotax at the weekend which was very instructive.

 

We used an Alpi Pioneer 200, I'd flown one before and I again thought what a nice little airplane it is - a pleasure to fly. The aircraft was fitted with a 2 blade Idrovario electric/hydraulic system and a Flybox controller.

 

The controller has both manual and constant speed modes.

 

There were a number of things to comment on:

 

• The system behaved really well and was very stable - no hunting or instability;
   
   
  
• The control system is pretty small and with big paws like mine it needed a bit of attention. Target revs in CS mode are set by turning a knob which changes revs in 50 rpm steps. The target rpm is displayed in large numbers on the LCD display with actual revs above it. It was very easy to over- or under-shoot your intended target. I imagine it might be quite a challenge in bumpy air.
   
   
  
• This particular aircraft cruised around 115 knots and that left only a very small margin of around 10 knots between cruise and Vne. Because the prop note doesn't change as you speed up, when using CS mode, it is very easy to creep up towards Vne. Apparently this a/c has been marked with an unusually low Vne for some reason but it took some watching;
   
   
  
• I was particularly impressed by the way the Pioneer behaved either on approach or when doing an engine failure. Once the prop is set to full fine the aircraft behaves as if it has an enormous sea anchor out the back. You can be in a position where you "know" that you can never make the paddock. But if you set full fine and put out full flaps the a/c comes down at an amazing speed. For those of you that know the Tecnam P92 which is no slouch coming down with full flaps - well the Pioneer with this prop system beats it hands down. Quite amazing.
   
   
  

 

 

All in all a great endorsement and well worth doing if you are going to fly an a/c with a CS or in-flight adjustable prop (besides being mandatory ;-))

 

Regards

 

Mike

 

 

[Matt]

Hi Mike,

 

Curious to know whether the Pioneer has a manifold pressure gauge to accompany the CSU. Also curious as to whether the RA-Aus CSU endorsement covers the theory of RPM and manifold pressure to achieve desired power, procedures for setting RPM & manifold pressure, emergency procedures if you have a CSU failure etc.

 

 

[Guest pelorus32]

Hi Matt,

 

yes a MaP gauge is mandatory. This a/c had an analogue MaP gauge but there are also digital ones available and some controllers also display the MaP.

 

The endorsement is pretty thorough and covers all aspects of power setting, engine failure, and system failure.

 

You can find the syllabus here: http://www.raa.asn.au/opsmanual/3-04.pdf on page 35.

 

Regards

 

Mike

 

PS: If you have a GA endorsement you can be signed out on that basis but I reckon it's worth at least a little time to learn the foibles of the Rotax 912/914 series with respect to a CSU.

 

 

[Matt]

Thanks Mike,

 

Curious about the "Landing and Circuit Operation" in 2.4, particularly the "check pitch reduction on finals". Having a GA CSU endorsement, my training and the few POH's I'm used to require transition to fine pitch during late downwind or during the base turn (base turn for the CT4). The theory being that in the event of a go round at any point on base or finals fine pitch is required to achieve the required power and response. This was consistent with the "manual variable pitch" prop we had in the Sportstar and the operating instructions for it.

 

I would have thought that leaving it to finals might be leaving it a bit late and add an unnecessary task during this final crucial phase of flight.

 

Question for the ops manual writers perhaps...

 

 

[Guest pelorus32]

G'day Matt,

 

I'm no expert on this - during the endo however fine pitch was selected before final and checked on final.

 

There is an interesting discussion on this in the FAA Airplane Flying Manual where they discuss a rationale for leaving the propeller pitch in a "cruise" setting on final...they don't necessarily advocate it but discuss it in terms of that setting providing better in-flight thrust response during approach than full fine.

 

Regards

 

Mike

 

PS: the transition to fine pitch in the Pioneer, accompanied the speed reduction to Vfe during the turn to base - it was used as part of the speed reduction strategy.

 

Another evolution that we tried a couple of times was selecting full fine and full flaps abeam the threshold on downwind at 1000' AGL. If you left the throttle closed you needed to be on a close downwind and make a direct beeline for the threshold or you would never make it!!

 

 

[facthunter]

Fine pitch.

 

Don't like the idea of fine pitch, throttle CLOSED. Depending on the pitch stop setting, you will be getting varying degrees of DRAG from the prop on approach, up to a significant amount. This will inevitably make the descent rate higher, and the approach path steeper. There may be times when this is desired, but I wouldn't like to see it considered as normal. You could expect to get a reduction of rudder and elevator effectiveness as well, so you should increase your approach speed to compensate, further increasing sink and approach angle.

 

Big engined pistons, (particularly Radials, which are more critical) do not like pitch fine throttle closed, situations,.... increase revs to that consistent with a "climb" power setting on downwind, and to full fine on final. This is where a powered approach is aimed for so the throttle is normally only closed during the FLARE. The only reason to go to "fine" is to cover the "go-around baulked approach" situation. In RAAus type aircraft the approach could be considered to be "stabilised" from say, 400 feet AGL so fine pitch should be selected by then, as it will certainly change the approach characteristics, (as would the selection of full flap), say. This certainly directs our attention to whether you use or don't use power on approach, and how you treat the "glide to the aerodrome" availability. When the conditions are gusty, I always use the powered approach technique, as you get much more control over the aircraft, (as an example). Nev

 

 

[Guest Cloudsuck]

Thanks Mike,Curious about the "Landing and Circuit Operation" in 2.4, particularly the "check pitch reduction on finals". Having a GA CSU endorsement, my training and the few POH's I'm used to require transition to fine pitch during late downwind or during the base turn (base turn for the CT4). The theory being that in the event of a go round at any point on base or finals fine pitch is required to achieve the required power and response. This was consistent with the "manual variable pitch" prop we had in the Sportstar and the operating instructions for it.

 

I would have thought that leaving it to finals might be leaving it a bit late and add an unnecessary task during this final crucial phase of flight.

 

Question for the ops manual writers perhaps...

That's interesting Matt, when I did my GA constant speed endo, I was always taught 'fine on late finals'. In my Yak, when you went full fine, it was like putting out a big air brake and doing it too early was a bit of a pain. It is a supercharged engine as well and power had to be way back before going fine. Everyone I know goes fine on finals.

 

 

[Guest pelorus32]

G'day Nev,

 

"closed" was in fact a sloppy word from me. The demonstration from abeam the threshold had it closed, normal ops however had it reduced to something sensible.

 

Regards

 

Mike

 

 

[facthunter]

Closed throttle?

 

Mike I am not particularly picking on that aspect, but the high drag thing is what bothers me. It could even be fun to fly the plane like that but ,as I have mentioned with radials it is frowned upon to subject them to high revs without power being delivered. (It overloads the big end bearing(s) and we have to think of the glide capability in some situations. This discussion needs to be had sometime and variable pitch propellers as their use impacts on the concept of gliding engine out. N.

 

 

[Guest pelorus32]

G'day Nev,

 

I should clarify that much of the endorsement was about the implications of setting the aircraft up in particular configurations - and what better way to get that across than to do it?

 

I guess what startled me from that demo was the magnitude of the drag in the full fine configuration. Whilst I knew of the implications of full fine - increased drag - I don't think I understood how much extra drag - at least in the case of this aircraft.

 

What you come out of an endo knowing, versus how you operate the aircraft - and what you do when it goes pear shaped - are two different things. I do think it's good though to understand what happens when you go full fine, for instance.

 

I hear what you say about going full fine turning base.

 

Regards

 

Mike

 

 

[Mazda]

My GA CSU instruction was to go fine on final, either with a "mixture, pitch, gear" type check, or a "pitch, undercarriage, flap, carby heat" check depending on who was instructing.

 

However, it can be done on downwind or base. (I suppose if the engine fails there you could always go coarse again). My initial CSU was on a two seat side by side aircraft which had the throttle on the left (left hand), the pitch in the centre, the flaps on the left (left hand), the stick in the centre (right hand), and the trim in the centre so it was an ergonomic nightmare! Think about it! I was taught to go fine on final with this one, but I flew the same aircraft more than a decade later and the owner had changed the checklist to go fine on downwind, which was much easier with this particular aircraft!!

 

Normally I'll do it on final, as part of PUFF checks, but the main thing I suppose is to do it some time before landing so you are ready for a go-around if required.

 

 

[Matt]

That's interesting Matt, when I did my GA constant speed endo, I was always taught 'fine on late finals'. In my Yak, when you went full fine, it was like putting out a big air brake and doing it too early was a bit of a pain. It is a supercharged engine as well and power had to be way back before going fine. Everyone I know goes fine on finals.

Interesting...guess it shows the variances in training, operating procedures, aircraft etc. The Parrot does have a slight air brake action going full fine but it's done after reducing power to 12-13" as you commence the base turn...as per the manual and it's only slight. Can understand that different aircraft have different procedures though.

 

Interesting thread...

 

 

[poteroo]

Whether you select full fine pitch or not - in most CSU aircraft, you'll note the RPM begin to decrease as you pull the MP back below about 13-14 ins. In this case, it's allowed the propellor to return to the fine pitch stops due to low oil pressure. This increases drag quite markedly and you don't need to physically go full fine. I'd prefer to see transitioning pilots identify the fall in RPM as above - then place the pitch into full fine on final. This can avoid a significant RPM overspeed where pilots simply go full fine without the power reduction.

 

happy days,

 

 

[Guest brentc]

"I suppose if the engine fails there you could always go coarse again"

Not quite, if there isn't any oil pressure when the engine fails, not much will happen!

 

Mike, what manifold pressure are you running in the cruise on this aircraft and how many RPM's for the 115 knots?

 

The Cirrus SR20/22 is an interesting machine as it has an automatic CSU and as such you don't need to have a CSU endorsement to fly it (there's an excemption on it for CPL flight test too as CSU is a requirement for that). It's like applying the handbrake when you back off the power and apply the flaps. Downside is that if something goes wrong with it you have absolutely no control over it. As far as managing and testing it, you do a run-up to 2,000'ish RPM and you can hear it change pitch and that's the extent of what you can do to check it.

 

 

[Guest pelorus32]

Takeoff 27/5700

 

Climb 27/5500 down to 26/5500

 

Cruise 25-26/5000

 

Cruise not below 23 inches for extended periods.

 

Boost reduced first before any pitch change in the circuit (or a reduction elsewhere for that matter).

 

Regards

 

Mike