Safety your Tach Drive Cap!

Ironflight · #1 09-16-2007, 02:40 PM

OK, I know that people have posted before asking how you safety wire the little Tach Drive cap on the back of the engine (at least, those of us using an electronic form of tach, so that we're not using a cable). Mine was one of those from Avery, and had a little hole in the "cap", but no way to safety the ring portion that actually threads on to the engine. I kind of figured "what's the point" of a piece of safety wire on the center post if it won't stop the ring/threaded portion from turing....right?

Notice I said that my cap "was" one of those from Avery?

Guess I'll be calling them in the morning! I took the top cowl off this afternoon to do a little pre-trip FWF check, and after almost 600 hours of flying, there was no cap. I knew it was tight last time the cowl was off a couple weeks ago, because I always check it. Ah well, it is somewhere on the ground somewhere, lonely and abandoned - hope it didn't hit anyone!

And the next one will be safetied, so that if/when it DOES unscrew, at least it will stay with the airplane!

Paul

N733JJ · #2 09-16-2007, 04:25 PM

Welcome to the multiple tach drive cover club!
After losing my first one, I did find a way to safety it that I believe will prevent the cap from coming off. Or, at least, as you said, stay with teh airplane!

Scott A. Jordan
N733JJ
675 hours

frankh · #3 09-16-2007, 04:30 PM

the TMX motor came with a back rubber cap that simply pushed over the threads?

Mibe did and..

a) hasn't come off and
b) I'm not sure if I care too much if it does.

Am I missing something?

Frank

petehowell · #4 09-16-2007, 04:35 PM

Hi Paul,

I JB welded a drilled nut to the tach cover and then safetied it to the oil sender safety wire location. Has held up well so far.

Ironflight · #5 09-16-2007, 06:31 PM

Quote:

Originally Posted by frankh

the TMX motor came with a back rubber cap that simply pushed over the threads?

Am I missing something?

Frank

You must have gotten the later, improved model!

Ah well....they're cheap!

cytoxin · #6 09-16-2007, 06:34 PM

has a good one that will hold a positive saftey. put it on last week. had to make a tab for it to safety to however.

AlexPeterson · #7 09-16-2007, 07:57 PM

I bombed my cap somewhere at about 100 hours. Guess I am going to fall right out of the sky for not replacing it.

Seriously, they aren't needed.

Ironflight · #8 09-16-2007, 08:53 PM

Quote:

Originally Posted by AlexPeterson

Seriously, they aren't needed.

You're really right - the drive is sealed. What's really funny is that my first thought was that I hate to have an exposed spinning thing there - and then I remember that I have that big orange SD-8 mushroom spinning away right next to it!

Paul

Jim Percy · #9 09-16-2007, 10:34 PM

ACS has one that's twice the price but is a much more logical design: http://aircraftspruce.com/pdf/2008In...l/Cat08409.pdf

mahlon_r · #10 09-17-2007, 05:05 AM

Are you guys tightening the cap by hand or using a pair of waterpumps? Out of all the tach cables I have ever seen connected and all the speedometer cables I have ever seen connected and all the tach covers I have seen connected, I have never seen one come loose and fall off. Did you put an O-Ring in the Avery model? Maybe that shrunk and the cap got loose? If tighten up with a pair of pliers I can't see how it could come loose..... maybe I am missing something
Good Luck,
Mahlon
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