JustAnAvGeek
Topic Author
Posts: 8
Joined: Tue Oct 23, 2018 5:36 am

Twin Otter Friction Knob

Tue Oct 23, 2018 6:19 am

A friend just came back from a trip in a twin otter and was asking me about this knob next to the feather knob on the overhead panel. He says it was labelled 'friction'. Could someone please explain what this does and why? If I'm wrong please correct me.
 
User avatar
Starlionblue
Posts: 18703
Joined: Fri Feb 27, 2004 9:54 pm

Re: Twin Otter Friction Knob

Tue Oct 23, 2018 6:53 am

At a guess, the two grey friction knobs control the "stickiness" of the throttles and the pitch ("prop") controls. The more friction, the harder the resistance to movement. Tighten to the max when you want them to stay in place, e.g. in the cruise. Loosen when you need to move them a lot, e.g. on the approach.

Image

The same sort of mechanism can be found on the throttle knob of many Cessnas. In the pic, you can see the knurled rotary control at the base (root?) of the throttle on a 172. Turn clockwise for more friction.

Image
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
JustAnAvGeek
Topic Author
Posts: 8
Joined: Tue Oct 23, 2018 5:36 am

Re: Twin Otter Friction Knob

Tue Oct 23, 2018 7:06 am

Great, this definitely answered that, thanks. Another question though:
Is the pitch levers for feathering control or is there a difference between the two?
 
BravoOne
Posts: 2912
Joined: Fri Apr 12, 2013 2:27 pm

Re: Twin Otter Friction Knob

Tue Oct 23, 2018 11:40 am

As I recall....bringing the pitch levers full aft would bring the props to a full feathered position. There were several predeparture checks that required a full cycle of the props. In addition the props had a auto feather feature that sensed a power loss via torque loss and subsequently cause the prop to feather automatically.
 
Max Q
Posts: 6820
Joined: Wed May 09, 2001 12:40 pm

Re: Twin Otter Friction Knob

Wed Oct 24, 2018 12:58 am

Some of our B727 aircraft had a
small lever on the center pedestal
to adjust throttle friction
The best contribution to safety is a competent Pilot.
 
BravoOne
Posts: 2912
Joined: Fri Apr 12, 2013 2:27 pm

Re: Twin Otter Friction Knob

Thu Oct 25, 2018 1:43 pm

Max Q wrote:
Some of our B727 aircraft had a
small lever on the center pedestal
to adjust throttle friction


That was a carry over from the 707/720, Never saw it on the 727-200, only the -100 series. When autothrootles came to the scene, manual friction went away.
 
Max Q
Posts: 6820
Joined: Wed May 09, 2001 12:40 pm

Re: Twin Otter Friction Knob

Sat Oct 27, 2018 11:25 pm

BravoOne wrote:
Max Q wrote:
Some of our B727 aircraft had a
small lever on the center pedestal
to adjust throttle friction


That was a carry over from the 707/720, Never saw it on the 727-200, only the -100 series. When autothrootles came to the scene, manual friction went away.



We had some ex PE -200’s that had the
friction adjustment levers, it never really
seemed necessary


The aircraft that didn’t have them had
no issues with throttles moving when
you didn’t want them to


The only problem I saw occasionally were
throttles that were very stiff and hard to
move, sometimes we would write them
up and Mx would adjust them



I think adjustable friction levers may have
been a holdover for Boeing from piston
engine days when everything vibrated
all over the place and needed to be
‘Locked down’ !
The best contribution to safety is a competent Pilot.

Who is online

Users browsing this forum: No registered users and 15 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos