Mailing List flyrotary@lancaironline.net Message #14961
From: Leon <peon@pacific.net.au>
Subject: Oil Pump Drive Key was Re: [FlyRotary] Re: Some things to check
Date: Sat, 8 Jan 2005 07:46:04 +1100
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Wendell,
 
Ed Anderson had a problem where the oil pump Wooodruff key wasn't in the keyway.  The drive was just taken by the friction of the tensioned nut. Worked for a while. Sooner or later,  the sprocket will slip on the shoulder of the pump shaft.  The symptom is intermittent loss of oil pressure,  which gets worse as the sprocket wears on the shaft shoulder.
 
So,  as I said in the post below,  always make sure that the key is actually in the keyway before fitting to nut & lockwasher.  The key itself is very tiny,  and it requires a bit of juggling to get it in the keyway in the sprocket.  I normally gently stake the keyway in the shaft so that the key can't slip out.
 
Hope this makes sense!
 
Leon
----- Original Message -----
Sent: Saturday, January 08, 2005 3:18 AM
Subject: [FlyRotary] Re: Some things to check was Re: [FlyRotary] Acceptable oil pressure

 
----- Original Message -----
From: Leon
Sent: Thursday, January 06, 2005 3:05 AM
Subject: [FlyRotary] Some things to check was Re: [FlyRotary] Acceptable oil pressure

Apart from a leaky pickup gasket,  or if the bolts were left finger tight (you have to be REAL careless to have this happen)  it is possible to have a fractured oil pickup pipe (rare but it can happen),  I've also seen blokes leave the oil pump bolts loose (again usually finger tight!),  or not stake the oil pump shaft lock washer (just carelessness),  or the Woodruff key wasn't located correctly (Ed's issue! - REAL easy to do - happens to me about every second or third engine).  Sometimes it takes two or three goes to get it in. They are real small & fiddly You must ALWAYS double check - use strong light or a torch to make sure that you can see the key is in the correct place once the sprocket in on on the shaft,  before fitting the nut & lockwasher. 
 
What would the symptom be if this wasn't done right? Don't remember having a problem getting the oil pump reassembled, can't be sure now if all was done correctly.
Wendell
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