Prop control

[rotorman]

Since I made the conversion to an A3B6 from the A3B6D the prop control is very stiff. I can, with one hand push in the button and pull out the control, but it is extremely stiff. The governor position was changed and the governor is new (rebuilt) and is the correct part number. The cable has no kinks and the cable to governor angle seems OK. I don't recall this being an issue before the changes were made.

Since the cable angle seems OK I want to check the force necessary to move the governor arm.  If I were to disconnect the cable at the governor would I be able to move the governor arm by hand?

[David Lloyd]

Yes, it should move easily by hand when disconnected.  Likewise, the cable should move with almost no friction when disconnected.

[PT20J]

Are you sure the new cable mounting hardware is installed correctly? There are some pictures hereabouts showing proper installations. A lot get installed incorrectly.

[IFLYIFR]

Could you let me (us) know who did the conversion and about how much it costs and how many weeks required? I’ve never like the dual magnetos in a single housing. Thanks.


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[PT20J]

49 minutes ago, IFLYIFR said:

Could you let me (us) know who did the conversion and about how much it costs and how many weeks required? I’ve never like the dual magnetos in a single housing. Thanks.


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It’s an engine swap. They are really two different engines. There are a lot of internal parts differences including the crankshaft. I believe Lycoming still gives a discount  for trading in a D core for a rebuilt A3B6.

Skip

[rotorman]

20 hours ago, PT20J said:

Are you sure the new cable mounting hardware is installed correctly? There are some pictures hereabouts showing proper installations. A lot get installed incorrectly.

The shop used bracket #50 in my airplane,  Bracket 50A is not available. I can't find it anywhere. Dan at Lasar said they use bracket 50 and install it 180 degrees from the drawing. The curved part ends up under the oil filter. The parts 50B and 50C are used. Part 50 can not be installed vertically since it does not have curvature that bracket 50A has at the governor mounting area. They are different designs.  Part 50 A installation does allow for fewer bends in the cable.  

The photos of the correct bracket installation that are on MS depict the bracket that is installed vertically. If I could find one I would switch as I believe that is the superior method.

[jetdriven]

We installed Bracket 50A in the same orientation as Bracket 50, horizontal. We still had to fabricate some metal to extend the end of the bracket another 2 inches or so so that you could put the clamp on the cable to hold it.

[rotorman]

14 minutes ago, jetdriven said:

We installed Bracket 50A in the same orientation as Bracket 50, horizontal. We still had to fabricate some metal to extend the end of the bracket another 2 inches or so so that you could put the clamp on the cable to hold it.

My mistake. I got disoriented on the drawing. My bracket is installed the same way as Bracket 50 in the drawing. No extension was necessary. Is your prop control stiff or do you feel it is normal? Do you have any photos of the installation?

[jetdriven]

prop feels normal.

[carusoam]

Looks like you may want to check two things…

1) Gov operation with the control cable disconnected…

2) Control cable, while disconnected…

Sounds like something may be binding…. Which could be really bad for cable health…

loss of RPM control can be really bad for Go Arounds…

PP thoughts only, not a controls guru…

Best regards,,

-a- 

[shawnd]

5 hours ago, carusoam said:

Looks like you may want to check two things…

1) Gov operation with the control cable disconnected…

2) Control cable, while disconnected…

Sounds like something may be binding…. Which could be really bad for cable health…

loss of RPM control can be really bad for Go Arounds…

PP thoughts only, not a controls guru…

Best regards,,

-a- 

I would definitely do #2 of what carusoam said above. I am going through cable replacement (all three) after finding that the vernier prop control doesn't move as freely through the full range of motion when disconnected from the governor. Mine was also likely the one that came from the factory! 

[PT20J]

Another thing to check is the angle between the governor control arm and the cable. You want it to be as nearly 90 deg as possible. Sometimes the arm on the governor needs to be clocked to get a good angle. This is done by loosening the screws on the back of the governor and rotating the entire pilot valve assembly. Don’t take the screws all the way out or the governor comes apart and don’t rotate the arm on the shaft.

Skip

[rotorman]

1 hour ago, PT20J said:

Another thing to check is the angle between the governor control arm and the cable. You want it to be as nearly 90 deg as possible. Sometimes the arm on the governor needs to be clocked to get a good angle. This is done by loosening the screws on the back of the governor and rotating the entire pilot valve assembly. Don’t take the screws all the way out or the governor comes apart and don’t rotate the arm on the shaft.

Skip

Mine was rotated but I believe not enough. Jetdriven must have solved this problem by adding two inches to the end of the bracket.

[rotorman]

The solution to this problem was adding spacers between the cable bracket and the cable thereby reducing the size of a bend in the cable. It took a surprisingly small amount of straightening to bring a satisfactory result. A small amount of unwanted bend seems to produce an oversized amount of friction in the cable.