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DHC-6 Questions:

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DHC-6 Questions:

Old 5th Jun 2010, 21:02
  #61 (permalink)  
 
Join Date: Jun 2010
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Hi people, I'm doing a job on seaplanes and I wonder if someone could give me the maximum component of crosswind in water DHC-6 and distances of T/O MTOW and LDG MLW, all distances in water.

Thanks,

O Molina
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Old 11th Jun 2010, 18:36
  #62 (permalink)  
 
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Twin Otter

Suggest contact Kenn Borek, they are the biggest Twin Otter operators in the world with floats.. Good Luck
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Old 4th Aug 2010, 05:22
  #63 (permalink)  
 
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Originally Posted by Phoq Af
... instead of 80kt, Flaps 10, id go 87+flaps 0 to clear obstacles... as I only see 1 and only Vx under DH certif/AFM/etc manuals. Am I wrong?

Moreover, 80kt is Vyse @ 12500lb, so the correct reply should be Vyse for Flaps 10 (ie 80-4/1000lb lighter than MTOW) and best RoC (SE+Flaps10 config). Computed accordingly. Wrong again?
It depends on what you are trying to accomplish, and what the circumstances are.

The aircraft achieves best rate of climb when in the flaps 10 configuration at 80 KIAS. It doesn't matter how many engines you have - 0, 1, 2, or 3. The aircraft also achieves best angle of climb (when in the flaps 0 configuration) at 87 KIAS.

If you wanted to fly up the side of the Matterhorn, and you were already established in level flight a few miles away from the base of the mountain, then for sure flaps 0 and 87 KIAS would give you the best angle of climb. That is the configuration I would choose for that task, and that configuration corresponds to the Vx published in the AFM.

On the other hand, if I had a short runway with a tall tree at the end, that means I am going to be configured with flaps 10 the moment I become airborne, because flaps 10 is the only approved takeoff configuration for the DHC-6 Series 300 or 400 landplane. Personally, I would leave the flaps at 10 and target 80 KIAS (best rate of climb for that flap configuration) in order to get over the tree. I would not retract the flaps and target 87 KIAS (best angle of climb), simply because the performance loss during flap retraction would greatly outweigh any performance gain arising from climbing in the flaps 10 / 87 KIAS configuration.

Michael
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Old 11th Sep 2010, 00:30
  #64 (permalink)  
 
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Thought I read somewhere that there was a specific reason that the multi crew call for flap retraction after take off was "selected AND running"?

Getting too old...
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Old 12th Sep 2010, 15:09
  #65 (permalink)  
 
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Quotes from V1:
Michael (the guy who writes the book... )

Guys, trust me on this one (fer' Pete's sake, I'm the person who writes the AFM) ....... (ad nauseum) .........

Yes, we get it already. You are the guy who apparently: [has] well over 5,000 hours of DHC-6 simulator instruction time ...

Get some real-world otter time and then maybe people will give you some of the respect that you are so desperately seeking.

My guess is that an aircraft fitted with survey, photographic, or research equipment today would
require ...


I cannot imagine an obstacle that would be so high ...

There is no value, none whatsoever, in using a higher initial climb speed...
Exactly, that is your guess, and you can not imagine, and there is no value that you can think of. No one should let the scope of their own experience, however vast or little, limit what they think is possible out in the rest of the world. There is always something a little beyond what we have experienced for ourselves.

I hate to write a post in the definitive tense, because it can sound arrogant.

Yes, it truly does.

Ah, OK, missed that nuance, sorry...

Lighten up already Mr. Moore, jeez...
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Old 12th Sep 2010, 20:41
  #66 (permalink)  
 
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Originally Posted by Duns3r
...Exactly, that is your guess, and you can not imagine, and there is no value that you can think of.
No, it's factual. For any given wing (flap setting) configuration, there will be one speed only that gives best rate of climb. In the case of the Twin Otter wing, in combination with a 620 HP limit and flaps 10 extended, best rate of climb will be achieved at 80 KIAS, assuming MTOW. At higher speeds, rate of climb degrades.

Michael
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Old 20th Sep 2010, 07:55
  #67 (permalink)  
 
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Experience.... experience

edited by mods

Last edited by DHC6to8; 8th Jun 2011 at 13:01.
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Old 21st Sep 2010, 23:28
  #68 (permalink)  
 
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Thumbs up V1...Ooops:

Trying to PM you, keeps bouncing back.

Please PM for my Pvt email.

H/Snort.
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Old 22nd Sep 2010, 00:20
  #69 (permalink)  
 
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Hi Rupert:

I'm not sure why the PM feature is not working.

I sent you a PM containing my direct email address.

Michael
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Old 22nd Sep 2010, 09:34
  #70 (permalink)  
 
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Thats the first time I've read about not reading the AFM as a point of pride. Not my style, but hey - you're not dead so bonus points to you.... I guess the plane is easy to fly!
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Old 22nd Sep 2010, 15:04
  #71 (permalink)  
 
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DHC 6 Copilot

Slightly off topic here..A friend of mine got hired to fly twotters as a copilot.. He is on a JAR license and wants to know if he can unfreeze his ATPL with twin otter time???? The company operates the airplane multi crew and the law in the particular country requires twotters to be operated 2 crew...

Would appreciate feedback from people who have been in similar position... Thanks in advance..
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Old 22nd Sep 2010, 21:40
  #72 (permalink)  
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I think so but...

He should check with his licensing authority. Sometimes they change their minds on this one but if it's required by legislation to be flown two-crew then time as an FO should be okay.
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Old 27th Sep 2010, 03:14
  #73 (permalink)  
 
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FO Otter time

Yes, it can be tricky....to log FO time on a US license it has to be an operation that requires two pilots (ie; 135 IFR with 10 or more pax; 121 ops etc) or an aircraft that requires two pilots (in the US, this is not an Otter). The company requiring it doesn't count, only government regs. If the country you are operating in requires it, I think that might do. Call OK City and ask...

If you can't log FO time, then you can always log PIC while sole manipulator of the controls (this doesn't mean you are acting as PIC, just that you are allowed to log it, as two pilots cannot fly the plane at the same time). Many Capt.s won't like this as it implies (correctly) that they cannot log the time that you fly.
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Old 27th Sep 2010, 16:30
  #74 (permalink)  
 
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Originally Posted by chuks
... if it's required by legislation to be flown two-crew then time as an FO should be okay.
This has been my experience as well - if the operating regulations require two pilots, then both pilots can log time appropriatly (PIC/SIC). The operating regulations (2 pilots required) trump the certification regulations (1 pilot required) in this case, because they are the more restrictive regulation.

Michael
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Old 28th Sep 2010, 03:24
  #75 (permalink)  
 
Join Date: Aug 2010
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Thanks for the info guys.. Appreciate it.. The regulation in this particular country requires the twin otters to be operated 2 crew since its a commuter operation..
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Old 23rd Oct 2010, 05:36
  #76 (permalink)  
 
Join Date: Oct 2006
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Just wondering,

Why is auto feather armed for take off but not for landing?
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Old 23rd Oct 2010, 15:16
  #77 (permalink)  
 
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Jsmitty:

During the take-off phase of flight, the aircraft has low kinetic energy and low potential energy. Hence the benefit of the autofeather system promptly identifying and feathering an engine following a loss of power.

During the approach and landing phase of flight, the aircraft has both kinetic and potential energy in reserve. An engine failure is less of a problem because the total power needed for approach and landing is less than what one engine alone can produce. For that reason, there is no need to use autofeather during that phase of flight.

There are other technical issues involved (for example, power lever position is steady during take-off, up at the forward end of the range, but variable during approach and landing), however; then issue of energy reserves (both potential and kinetic) is the main reason.

Michael
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Old 23rd Oct 2010, 15:43
  #78 (permalink)  
 
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May also not have enough power applied to arm the autofeather system on the approach.
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Old 23rd Oct 2010, 18:06
  #79 (permalink)  
 
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Originally Posted by Cardinal Puff
...May also not have enough power applied to arm the autofeather system on the approach.
Correct, but that is more an 'effect' rather than a cause. Because the system is designed only for use during take-off, and because the system has to allow a rejected take-off to be carried out without resulting in an autofeather, both power lever position and engine torque pressure are sensed.

The autofeather system will not arm unless torque on BOTH engines is above a specified value (this will vary slightly depending on mod status), and unless the power levers themselves are physically quite far forward. The power lever position is sensed in order to allow deactivation (disarming) of the system during a RTO prior to torque dropping below the torque sensor threshold.

So, even if enough power was carried in the approach to satisfy the torque sensor threshold, it is very unlikely that the power levers would both be far enough forward to arm the system.

Michael
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Old 23rd Oct 2010, 21:21
  #80 (permalink)  
 
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I agree with what your saying regarding low power in the approach and landing and as with other aircraft types the system wont arm anyway.

However for the go around you would be in the same position as for a normal take off with low kinetic and potential energy and if selected the autofx system would be armed.
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