Idle screw wire tie

[ceslaw]

Has anyone had an issue with the idle screw on the CC340 coming loose and even falling out in flight?

Has anyone drilled a hole in the idle screw so it can be wire tied?

I have been told by one pilot that this was indeed an issue. Before removing and drilling the idle screw wanted to see if anyone else had any experience with this.

IMG_2408.jpg

[Andy]

Has anyone had an issue with the idle screw on the CC340 coming loose and even falling out in flight?

I doubt this carb is unique to the CC340. The spring is what should keep the mixture screw in place and no carb I have adjusted has the mixture screw wire locked.

Is the mixture screw on this aircraft so far out that the spring does not keep it in position? If so, why is the mixture screw so far out?

[ceslaw]

Andy: The screw shown in the picture is in the position it came in from the builder where it has worked splendidly for 200 hours. No issues on this end, but the question noted had come up and wanted to see if anyone had ever had a problem with it coming out.

[jump4way]

I know of one person that his this very scenario happen. It ended in an unexpected off airport landing for him.

[ceslaw]

I know of one person that his this very scenario happen. It ended in an unexpected off airport landing for him.

That makes three anecdotal reports of this occurring of which I am aware. Thanks.

[Andy]

That makes three anecdotal reports of this occurring of which I am aware. Thanks.

I wonder if it could be 3 anecdotal reports of the same event. These carbs have been flying for probably over 70 years. If idle screws were falling out with any frequency there would have been an AD years ago.

I still don't see how an idle screw set in the normal adjustment range can fall out. Is it possible that the screw was out so far out that the spring was ineffective? Could the screw have been out much further than intended in an attempt to compensate for another problem that was causing incorrect idle mixture?

Safety wire is cheap though and an easy way to mitigate any percieved risk.

[ceslaw]

Andy

Valid observation, although I know personally one of the three pilots that had this happen and it is he that strongly recommended adding the safety wire.

Agree with you. Cheap insurance.