Prop Spinner

[6781]

How important is the prop spinner? I can’t remember not seeing one on any 120/140 I come across digitally or in person. Any ever not use it?

Nick

[5099]

Some aircraft have a spinner listed on their required equipment list. These aircraft require a spinner because of engine cooling. However, some do not require a spinner. For example, a C-150G does not require a spinner, despite having a large pointed spinner from the factory. But, later models do require a spinner and it shows on their equipment list as required.
It is my understanding that the C-120/140 does not list a spinner as a required piece of equipment. No spinner or a Skull Cap spinner is acceptable. At least that’s how I see it.
Steve.

[6643]

If you check the parts manual, it appears that the original prop was wooden and no spinner is specified. (Figure 1). IF you look in the back, under optional equipment, you'll find the McCauley and Sensenich props (Figure 61). Also listed with them is a skull cap spinner.Whether the spinner is optional given the optional prop is installed is debatable. The Aircraft Specification lists the props and a spinner, but the spinner is not shown as required for the prop installation, so, IMHO, the spinner is optional.

Why you might want to do away with it is another question...

[6781]

Thanks for the replies. What a great resource this site is. To answer the “Why”, I am looking at comparing props and wanted minimize the mounting of things if they are not critical. I was told similar info about the cooling effects of spinners and wanted to check the opinions here. Ultimately the spinner will be in for the long hall.

Thanks again!

[8278]

I was flying around in my little silver and red bird (C140) the other day and heard a bang.
Thought that I had hit a bird.
Checked out the plane when I landed and couldn't see any damage.
Took it to my LAME yesterday to sign out the 100-hrly and on looking around the aircraft when giving it a bath I realized that the little spinner was missing.
Shame because it gave it a bit of character on the nose with the nice polished McCauley prop.
I had tightened it previously because the last person who had obviously fiddled with it had over tightened the center screw and cracked around the screw/ bolt hole.
Anyway to my point, from my understanding the spinner is only there for looks really nothing more, but having said that does anyone know where one can buy a replacement even if it isn't alloy and does anyone know what the ball park cost for a spinner would be?
Probably lucky when it hit the prop it didn't come back through the windscreen.
Only scuffed the prop and a little nick higher up where it hit it on the go-around.
Has anyone else had this happen to them?
Thanks in advance for your replies.
Rick Parks

[6643]

This one is the one you want. About $95.

One year, at annual, when I was a mere software engineer, my IA had me replace the grubby cad plated screw holding the spinner on with a shiny stainless one. A few hours later I hit the same bird you did. Scored the back of the prop badly enough I had to have it overhauled.

The hardware holding the spinner on employs a Tinnerman nut. Tinnerman nuts require type "B" screws, with a constant minor diameter. When you tighten the screw the tabs of the nut dig into the screw and lock it in place. Type "A" screws, also known as self tapping sheet metal screws, have a tapered diameter and a smaller minor diameter, too small for the nut to grab.

Think about it: the spinner is the only part that can come off in flight and hit the prop...

[6597]

Latest EAA magazine from July had an article about floating clip nuts on spinners. It mentions that although tinnermans are a common useage for skullcaps it seems the floating clip nut is a better choice. Also mentions not to run the spinner mount without the skullcap. A failed tinnerman or using the wrong screw can lead to a departing spinner with maybe some prop damage...


https://www.aircraftspruce.com/catalog/ ... kkey=51325

[8278]

Thanks guys avice noted. Yes my LAME doesn't like them but I thought that I would just get another one for completeness.
I can see that they could be a problem if they came off and hit the wrong part of the aircraft like through the windscreen.
John thanks for the advice where to buy one, as it will represent delivered less than AUD$200 I will order it and keep it for static display only.
I was lucky it only nicked the prop slightly and was easy to file out. Again thank you very much.
Rick P.

[6643]

I will ... keep it for static display only.

Thre's no need to do that. As long as you have the correct hardware there's no danger of it coming off. If the bracket has a tinnerman nut you need a type "B" screw, identified by the Blunt tip. If it uses a machine screw and a floating stop nut you're good to go.

Also, if you're going to fly without the spinner, you should, as noted above, be removing the bracket as well, which means removing two of the prop bolts, which means retorquing and safetying the bolts, which means you need an A&P. (I'm glad they don't call us LAME here in the states...)

[Edit] The photo appears to show a machine screw.