Overhead air scoop knob

[RobertGary1]

A 1/4" amplifier knob is legal for your 1960s airplane. You are allowed to substitute parts and meterials for the substantially same or better quality. Can you make a determination the plastic 1/4" shaft plastic knob held on with a set screw is substantially similar in fit form, and function to the original 1/4" plastic shaft knob held on with a set screw?  

 

To qualify "You" in this case is an A&P who can approve of owner produced parts in some cases. A pilot cannot log the install of an owner produced part on his own. Its funny to say that the plane will fall out of the sky with an un-certified part but sadly its not funny for the FAA.  I've actually seen them go after people for little things like this after an unrelated incident.

 

On the flip side of that, when my Lycoming factory new engine disassembled itself the FAA was all on top of it. They poured through my logs, etc. After discovering that I had my gear inspection current, etc they lost interest and closed the investigation. 

 

-Robert

[Yetti]

Byron,

I'm not quite sure what you are saying. Should tie wraps not be used to hold fire sleeves on. I have seen fire sleeves split to install without removing a fitting. Tie wraps seem like a good way to hold them on. I have also seen fire sleeves installed "in the middle" of a length of tubing, and a tie wrap seems a good way to keep them where they belong.

I believe the point beyond that ty wraps are not "certified" is that the ty wrap will melt in a fire, then the fire sleeve will fall off and not do what is  supposed to do.    Hence you see the metal band holding on the fire sleeve in the picture.

[Yetti]

Oh and my use of the word ty wrap is improper trademark infringement.  Plastic cable tie is a better choice of words.   A plastic cable tie that is a true Ty Wrap will have a metal piece for the locking mechanism.

[DonMuncy]

I wonder if it would be proper to use a strand of safety wire where the tie wraps are.

[RobertGary1]

Oh and my use of the word ty wrap is improper trademark infringement.  Plastic cable tie is a better choice of words.   A plastic cable tie that is a true Ty Wrap will have a metal piece for the locking mechanism.

 

Lycoming shipped my engine with a pack of plastic cable ties with instructions to use them to route the plug leads. At least in that application, it makes it pretty official.

 

-Robert

[jetdriven]

Byron,

I'm not quite sure what you are saying. Should tie wraps not be used to hold fire sleeves on. I have seen fire sleeves split to install without removing a fitting. Tie wraps seem like a good way to hold them on. I have also seen fire sleeves installed "in the middle" of a length of tubing, and a tie wrap seems a good way to keep them where they belong.

 

It depends, if its used for anti-chafe puposes I think zip-ties are fine. But when you split the hose the instal it with plastic zip-ties, I fail to see how it is suppsed to withstand a direct flame for 20 minutes .

[jetdriven]

To qualify "You" in this case is an A&P who can approve of owner produced parts in some cases. A pilot cannot log the install of an owner produced part on his own. Its funny to say that the plane will fall out of the sky with an un-certified part but sadly its not funny for the FAA.  I've actually seen them go after people for little things like this after an unrelated incident.

 

On the flip side of that, when my Lycoming factory new engine disassembled itself the FAA was all on top of it. They poured through my logs, etc. After discovering that I had my gear inspection current, etc they lost interest and closed the investigation. 

 

-Robert

 

Sure, I meant A&P signs off and installs.  By "you" i mean you hire the mechanic. You're still responsible for airworthiness.

[Yetti]

Besides not making it for twenty minutes in direct flame. If you go and tug on most of the plastic cable ties under the cowl you will find that they just break off due to fatigue of the heat on the plastic. There are stainless steel cable ties http://www.harborfreight.com/household/cable-ties/12-in-stainless-steel-cable-ties-25-pk-60330.html%C2'> The stainless crimp banding tool would be the right tool for the job.

[carusoam]

Using nylon for flame resistant applications would be a bad choice.

It is a long time to the ground in the event of an engine fire aloft.

Best regards,

-a-

[StinkBug]

LOL, I knew someone would have to go and be the logbook police. It's a knob for a noncritical system, and it's owner produced. Not exactly something any A&P or IA is going to sweat signing off. I never did find the logbook entry for the amplifier knob that was installed before I made this one though...

[Marauder]

LOL, I knew someone would have to go and be the logbook police. It's a knob for a noncritical system, and it's owner produced. Not exactly something any A&P or IA is going to sweat signing off. I never did find the logbook entry for the amplifier knob that was installed before I made this one though...

Don't you know that there is a 1:1,000,000,000 chance that non-approved knob will fall off and jam itself under the Johnson bar?

Sent from my iPad using Tapatalk

[N201MKTurbo]

This just goes to prove how reliable and well made a Mooney aircraft is, when we spend so much time discussing a knob who's worst failure mechanism is a failure to blow cool air on the pilot.

[M20F]

This just goes to prove how reliable and well made a Mooney aircraft is, when we spend so much time discussing a knob who's worst failure mechanism is a failure to blow cool air on the pilot.

Well you get a knot or two closing it so mission critical :-p

[StinkBug]

This just goes to prove how reliable and well made a Mooney aircraft is, when we spend so much time discussing a knob who's worst failure mechanism is a failure to blow cool air on the pilot.

 

Actually my old knob had no problem opening the scoop, the problem was getting it closed again in flight. So I'd say the worst failure mechanism is a failure to stop blowing cool air on the pilot.

[MyNameIsNobody]

A 1/4" amplifier knob is legal for your 1960s airplane. You are allowed to substitute parts and meterials for the substantially same or better quality. Can you make a determination the plastic 1/4" shaft plastic knob held on with a set screw is substantially similar in fit form, and function to the original 1/4" plastic shaft knob held on with a set screw?

Knob and lock screw are both metal.

[jetdriven]

Mine is plastic. There are metal 1/4" shaft knobs on eBay.

[MyNameIsNobody]

I am just seeing how many pages we can get on the knob. 5? 10?

[RLCarter]

Make one or have it made, if the knob looks original chances are no one will notice or question it. I have made several things for some of the local A&P's and IA's. Here's a the hold open I duplicated for my baggage door

[MyNameIsNobody]

bought one of those...from Mooney...for <10 bucks a few years ago...