Received-SPF: none
 receiver=logan.com; client-ip=68.230.241.41; envelope-from=dale.r@cox.net
Message-ID: <49ABF0EE.1090106@cox.net>
Date: Mon, 02 Mar 2009 07:45:02 -0700
From: Dale Rogers <dale.r@cox.net>
User-Agent: Thunderbird 2.0.0.19 (Windows/20081209)
MIME-Version: 1.0
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Missing Key
References: <list-3523185@logan.com>
In-Reply-To: <list-3523185@logan.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 8bit

Folks,

Is there any good reason to _not_ locktite (red) the key
into the pump shaft groove?

Dale R.

Ed Anderson wrote:
>
> Very good point, Tom.
>
> Don’t know how I could have forgotten the problem I had with the key 
> for the oil pump shaft. In fact, I flew for 10 hours with the key 
> missing – only the clamping force of the nut on the shaft holding the 
> gear to the shoulder of the shaft. While at Shady Bend (Tracy Crook), 
> I unintentionally left my throttle at full open after we had comparing 
> throttle bodies and intakes.
>
> The next morning was a bit cool and I was using 50 weight oil. I 
> hopped into go do some flying with Tracy and Finn Lassen, when I fired 
> up the engine (Having forgotten to close the throttle from the 
> previous days inspection), the engine caught and immediately zoomed to 
> 5000 rpm before I could hastily pull the throttle back. I noticed 
> lower than normal (around 20-25 psi) oil pressure while taxing to take 
> off and just told myself it was the cold weather, cranky sensor or 
> gauge, but by the time I got to take off position, I notice the oil 
> pressure had never gotten above 25 psi when normally at taxi rpm I 
> would have around 40-50 psi.
>
> Fortunately, I could not bring myself to take off with that condition 
> (even though I kept telling myself there was nothing wrong). After 
> much trouble shooting, I decided I had to pull the engine off 
> (thankfully, Tracy Crook had a great facility to do that in) . I 
> removed the oil pan and as I took it over to wash it out, I hear a 
> metallic clanking in the pan – yes, you know what it was – a much 
> battered key for the oil pump shaft. When I had pushed the sprocket on 
> the shaft, I had pushed out the key but unfortunately, it did not drop 
> down. It got trapped between the sprocket wheel and the soft aluminum 
> oil pump housing (the indention was in the soft aluminum) from the 
> force torquing the nut down. This had push the sprocket against the 
> trapped key which in turn had pushed the key against the housing and 
> trapped it there – probably until the first engine run. Fortunately, I 
> had torqued the nut down as specified – which some folks think is a 
> bit high for that small a nut, but glad I had. I’m also glad in hind 
> sight I left the throttle open and it was a cool morning – who knows 
> when it might have let go.
>
> So now when I rebuild an engine, I take a small paper clip and bend 
> the end out so I can stick it in the keyway hole after putting the 
> sprocket on. If it goes in all the way – the key is not in its slot!
>
> Moral of the story, it can happen to any of us – so take time and 
> check. As Tom mentioned, it can be a bit of a hassle to get the keyway 
> in the slot and sprocket on – if it falls out (as it will most of the 
> time) and you hear it/see it you are OK. But, if it gets trapped as my 
> key did – you won’t get that clue. So use a paper clip, inspection or 
> something to insure the key is where you think it is.
>
> Also pay attention to your gauges and your gut they are both always 
> telling you something – if you will only listen {:>)
>
> Ed
>