Dash-8 yaw damper useage
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
Dash-8 yaw damper useage
Our company fly's the DHC-8 100/200/300's. For the 300's on certain runways, our takeoff/landing data asks for a flaps 15 takeoff instead of the usual flaps 5. In the -300, if we use flaps 15 we have to DIS-engage the yaw damper for the takeoff, only to re-engage it right after liftoff, clicking it on right as the wheels lift the ground for the most part. I cannot come up with a good reason as to why we cant use the yaw damper for a flaps 15 T/O in the -300. Anyone have any insight?
Bottums Up
DHC8-FO
It's years since I've flown a Dash8, but I have a vague memory that a restriction came about in the late 90's, which I think was caused by a VMCG anomaly during take-off, related to the yaw damper either doing, or not doing, its thing.
Sorry about the alzheimers.
It's years since I've flown a Dash8, but I have a vague memory that a restriction came about in the late 90's, which I think was caused by a VMCG anomaly during take-off, related to the yaw damper either doing, or not doing, its thing.
Sorry about the alzheimers.
Join Date: Dec 2004
Location: .
Posts: 118
Likes: 0
Received 0 Likes
on
0 Posts
Gday,
Clarrie, I remember something about Vmcg being greater than V1 when at light weights at F15. I recall if you could use an assumed weight of ??.?T and the associated speeds, then you could leave the yaw damper on.
Again, too long ago. Maybe all the XXXX is finally catching up with me
Cheers,
Con
Clarrie, I remember something about Vmcg being greater than V1 when at light weights at F15. I recall if you could use an assumed weight of ??.?T and the associated speeds, then you could leave the yaw damper on.
Again, too long ago. Maybe all the XXXX is finally catching up with me
Cheers,
Con
Gender Faculty Specialist
We had a similar discussion a while ago, albeit about the Q400.
The Vmca and Vmcg actually reduce, not sure how much though, with the yaw damper disengaged. This happens because the rudder reacts quicker to your input as it's not trying to counteract any yaw you are trying to produce. This would seem to confirm Con's info assuming that the actual reduction in Vmc speeds was enough to bring Vmcg back below V1. Using Flap 15 also gives you slightly better lateral stability too.
I haven't come across this problem on the 400 before and I'm assuming because it's a bit loooonger than the old classics it doesn't have the same stability probs. Greater moment arms and all that.
Hope this is a help,
The Greater Chested One
PS I would be intersted to know the official reason.
The Vmca and Vmcg actually reduce, not sure how much though, with the yaw damper disengaged. This happens because the rudder reacts quicker to your input as it's not trying to counteract any yaw you are trying to produce. This would seem to confirm Con's info assuming that the actual reduction in Vmc speeds was enough to bring Vmcg back below V1. Using Flap 15 also gives you slightly better lateral stability too.
I haven't come across this problem on the 400 before and I'm assuming because it's a bit loooonger than the old classics it doesn't have the same stability probs. Greater moment arms and all that.
Hope this is a help,
The Greater Chested One
PS I would be intersted to know the official reason.
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
....
Interesting. It seems you all are hovering around the same ideas. Ill have to make an attempt to get in touch with training dept. guys to see what they have to say. Thanks for everyones insight.
Join Date: May 2004
Location: eastern europe
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
we are talking about that prop aircraft from canada, right??? iīm confused, because i also fly the thing and have never heard of this... but, on the other hand, i canīt remember having had to use flaps 15 for take-off. but iīm going to throw this question into the general direction of the tech. pilot and see what he has to say, seeing that iīll be making my first journey to Naxos next month. and i think that with less than 900m of runway to play with flaps 15 is going to be an issue!!!
Join Date: Dec 2004
Location: .
Posts: 118
Likes: 0
Received 0 Likes
on
0 Posts
Knertius,
It will depend on which Canadian Bus you strap to your Bum
100,200 or 300.
You should find a placard in a 1 or 200, on the F/O's side normally, regarding the assumed weight required for a F15 TKOFF with YD on. Otherwise it should be YD off til L.OFF.
As I said earlier, its been a few years for me but it was a happening thing back then.
Cheers,
Con
It will depend on which Canadian Bus you strap to your Bum
100,200 or 300.
You should find a placard in a 1 or 200, on the F/O's side normally, regarding the assumed weight required for a F15 TKOFF with YD on. Otherwise it should be YD off til L.OFF.
As I said earlier, its been a few years for me but it was a happening thing back then.
Cheers,
Con
Join Date: May 2004
Location: eastern europe
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
thanks Con!
the original post by DHC8-FO states that this is the procedure for the 300. you mention the 100 and 200. so, it seems to me, the original post could have mentioned the 300 by accident. we have 300s and 400s and no such procedure. going to ask the FO today to check for any hidden placards under his feet when he puts them up against the instrument panel during the relaxing 25 minute flight that awaits us
cheers
k
the original post by DHC8-FO states that this is the procedure for the 300. you mention the 100 and 200. so, it seems to me, the original post could have mentioned the 300 by accident. we have 300s and 400s and no such procedure. going to ask the FO today to check for any hidden placards under his feet when he puts them up against the instrument panel during the relaxing 25 minute flight that awaits us
cheers
k
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
...
Back again. Nope, no mistake was written in my initial post. The flaps 15, no-yaw damper procedure, for our company anyway, is only for our -300s and not for the 100/200's. I still cant really stumble upon a concrete answer.
Join Date: Apr 2001
Location: JAAland
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Capt. Greaseon
My outfit flies the 100 / 300. We have no restrictions on the 300 for yaw damper usage. However on the 100 we can only use the yaw damper with 5 flap above 31750lbs.
Same with mine before, however, after they bought (another) supplement we can leave the little pointy light on on every takeoff. I believe it has something to do with YD-auto disconnect during eng. failure. Try testing the autofeather system while the YD is on and the engines are off.
What really surprise me with the DH8 is that its newer addition, the Q400, isnīt certified for auto feather use except for TKOF!!!
brgds
Join Date: Feb 2006
Location: United States
Posts: 216
Likes: 0
Received 0 Likes
on
0 Posts
My understanding is that back in the beginning of the program the original flap setting for takeoff was 15, and the number 1 airplane did not have a yaw damper installed. Somewhere along the line it was decided that since the certification work was done with no yaw damper it had to be flown that way.
Flaps 5 data was obtained later, in another airframe, with the yaw damper on.
With regard to the -300, I believe that the #1 airframe was plugged and used for the aerodynamic parts of the certification, so the same issue carried into that model.
Or so it was explained to me long ago by some folks in Downsview.
Flaps 5 data was obtained later, in another airframe, with the yaw damper on.
With regard to the -300, I believe that the #1 airframe was plugged and used for the aerodynamic parts of the certification, so the same issue carried into that model.
Or so it was explained to me long ago by some folks in Downsview.
Join Date: Jan 2000
Location: South Africa
Posts: 510
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by SlowAndSilly
.... however, after they bought (another) supplement we can leave the little pointy light on on every takeoff.
Originally Posted by SlowAndSilly
What really surprise me with the DH8 is that its newer addition, the Q400, isnīt certified for auto feather use except for TKOF!!!
brgds
brgds
Join Date: Apr 2001
Location: JAAland
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by nugpot
That is the real answer. You can do anything if you purchase the right supplements. We do Flap 0, 5, 10 and 15 take-offs, all with YD engaged.
You can buy another supplement for that. SAS (I think) arms auto-feather for approach with the Q400.
You can buy another supplement for that. SAS (I think) arms auto-feather for approach with the Q400.
How autofeather is used with SAS I donīt know, but Iīve been told the standard autofeather system on the Q400 doesnīt allow AF on other than on TKOF.
Join Date: Jun 2006
Location: B.F.E.
Posts: 228
Likes: 0
Received 0 Likes
on
0 Posts
Over here we fly 100's and 400's; yaw damper OFF T.O for the 100 w/ flaps 5 or 15 (normally 5, 15 for a couple of short runways we frequent); flaps 5, 10 or 15 (normally 15) w/ yaw damper ON T.O. in the 400.
Join Date: Feb 2005
Location: sYDNEY
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
We operate the 100/200/300 series and only have such restrictions on the 100. My understanding is that with the yaw damper ON, reaction to a OEI is impeded as the damper will attempt to damp out the correcting yaw input by the pilot. If your BRW (actual or assumed) is greater than 14.4t, the V1 is greater that 91kts giving a little more directional authority in the event of a v1 go. It only appies to flap 5 take-off. All flap 15 take-offs are yaw damper off. Doesn't apply to the 200/300 though. There are so many mod status differences for the aircraft it could be different for different operators.
Aviator
Join Date: May 2001
Location: Norveg
Posts: 483
Likes: 0
Received 0 Likes
on
0 Posts
We operate the 100/300/400. There is, as SlowAndSilly said, a mod. you can install, that will disengage the YD when the engine autofeathers. After we modified our 100-series, we can take off with YD ON, regardless of flap setting. When performing the autofeather test each morning, we check that the YD is disengaged as the engine autofeathers. But I guess that mod costs money... If my memory serves me right, you can use YD for flap 5 take-offs on the -100 without the mod?
