DHC-6 nose wheel
 

I am a pilot of DHC-6 of First Flying, located in Japan and that is Japanese commuter company.

This summer we bought two brand new DHC6-400 but soon after we started services, one of them has crashed.
After landed, aircraft suddenly veered to right and hit the fence.
our flight service is still suspended since accident happened and we are under investigation what is the cause of accident.




Now our situation is that we do not have any idea what is the cause of accident and what is the recovery action once

airplane suddenly veered to left or right.
By now, what we figured out was nose wheel was not centered on touch down but veered to right to some degrees even though nose wheel steering lever was in a center position.
All of our pilot does not have experience flying with DHC-6 much and most of the destination airport are about 800m short runway.

Viking(maker) does not give us certain information relating to nose wheel trouble, nor give us

any technique how to make recovery action once aircraft veered to left or right.

Considering those, we ourselves have to figure out and look for the way to recover from our accident.
If anyone know about these it would be great help for us even it is tiny things.



Your support would be great helpful for us.


thank you,


-Takataka
First Flying, pilot

Mmmmmm, dont think I will be booking a ticket with First Flying

Use rudder and differential braking to stay on the runway, also use the elevator to lift the nose wheel off the ground to regain differential control while you slow the aircraft.

thanks for your advisement!

You are welcome.
The Twin Otter has a lot of rudder and elevator authority at low speed so don't be afraid of using full deflection if needed.

I flew those airplanes on both wheels and floats, it was fun to the last day.

The place I worked for had 2 go off the runway:
The first one was caused by a new Captain with no time in the DHC-6, he just screwed up.
The second was an attempt to take off with full flaps, the main wheels lifted off and the nose wheel stayed on the ground like a wheel barrow, they veered off to the left and hit the glide slope shack for runway 8 at San Juan airport in Puerto Rico.
The moral of the story is to use full aft elevator control if you try to take of with full flaps. :sad:

I just now read the accident report: Looks like they had a flat main tire.
Same happened to me, use the opposite brake to go straight, ar at least stay on the runway.
I remember there was a strong vibration, like the airplane was shaking itself to pieces.
Had to stop on the runway and call for a bus to get the pax off.

As mentioned above by TD, the rudder has a lot of authority and [rudder pedals] should be used for directional control; if necessary along with asymmetrical engine thrust .

During the takeoff roll and after landing, the tiller should NOT be used (or only with extreme caution and at low speeds), otherwise the outcome could to be less than desirable.

I heard of inexperienced Twin Otter pilots unexpectedly veering off the runway and damaging the aircraft beyond repair, during take off and/or immediately after landing, because of just that.

If you could know please let me know.
1. Why do you think airplane veered to left or right suddenly it get on the ground?
Seems like old type of DHC6 doesn't have that kind of trouble.
2. As far as you know, how many times have you heard the incident airplane veered to left or right suddenly airplane get on the ground though nose wheel lever is in the center position?
3. What is your recommended technique to recover and is some time happen airplane off runway no matter what you made all recovery action?
4. Our operation is that flap is retracted once get on the ground. At that moment? Hydraulic be used to flap, steering and brake simultaneously, considering those, because of multi task to the hydraulic, is this kind of trouble may happen you think?

Appreciate for your support.
I am looking for your answer.

Higashijima

That is fine, I am using this technique as well. If anything, it will put more weight on the wheels, improve stability and improve breaking action.:ok:

I suspect your pilot got into this accident because he touched the tiller (nose wheel steering).

The bottom line is this: do NOT use nose wheel steering -- do NOT touch the tiller -- during the takeoff roll and after landing! Only use the rudder pedals!

PS. Separately, I heard of a pilot in Gabon who landed long and too fast, bounced several times, then lost control. The aircraft ended up in ditch, upside down, only minor injuries.

The Twin Otter is the best aircraft I have flown, it has amazing performances and capabilities, it is easy to fly, but it will bite if not handled properly, or with inexperienced pilots.

1) according to a report from Okinawa, a flat tire was the culprit.
2) never heard of it, happened to a collegue on take-off, he screwed up
3) use all available controls, rudder, brakes, whatever to stay on the runway
4) flap retraction is probably not a factor, unless both pilots get distracted fumbling with the flaps. Forget about the hydraulic nose wheel steering, the rudder gives you plenty directional control down to slow speed. You only use the tiller to taxi on the ramp area and to make sharp turns on the runway. If you think the hydraulics gave un-commanded nose wheel deflection which sent the airplane off the runway, you are probably wrong. (The odds are much higher that the pilots did not control the plane)

DHC6 nose wheel trouble
 

A part from a nose wheel steering trouble of DHC6,
are there any trouble or characteristic which we have to take care?
If do so, would you give us the way to cope with under certain condition as a preventive action?

Thank you.

-takataka

It has been quite a while since I flew the Twin-Otter, can't think of any problems, design wise or otherwise.
I seem to remember a case in Alaska where ice on the tail may have contributed to a crash

I did all of my Twin-Otter flying in the Caribbean Islands where salt and corrosion was a factor. Some of us never armed the auto-feather system as corrosion in micro switches could cause problems, but not sure if that was old-wives tales or not. With the FAA riding on the "jump seat" behind the cockpit, I always armed the system as it was required at the time.

The Twin Otter is a great handling airplane with lots of low speed control followed by impressive short field capabilities and not difficult to fly at all, but YOU have to be in charge of the airplane: Don't let it take you off the runway and don't let it fly too fast or too slow on finale, be in charge and have fun with it. I am sure the Canadians have good training programs with good instructors so there should be no reason to not learn to fly it properly. :cool:

TowerDog san

Thank you for your information, everytime!

-takataka

Ok Takatasan, let us know how it goes.
Just toss the book away and fly the airplane. (Seriously)

I should bow away and let the current and qualified DHC-6 guys advise further, they know more than me, I just have a big mouth and have not flown the Twotter in years. :sad:

You had a good support anyway.
Thank you! arigato!

-takataka

We had a couple pilots end up off the runway because they landed with the tiller off from center. As soon as the landing gear came down, it turned off the runway. One ended up ripping the nose gear off.