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Date: Mon, 03 Aug 2009 11:16:59 -0400
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From: "terrence o'neill" <troneill@charter.net>
References: <list-3793076@logan.com>
Subject: Re: [LML] Build with maintenance in mind
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Excellent note.  Don't know how many times I'v e complained about the 
archaic cowl attachment used by our 235/320.  On my (own designed) last 
planes, the Model W and the Magnum, both had cowls that opened in a few 
seconds (with gloves on), with four camlocks from an old BT-13 cowl. 
Instead, trying to live with this project, I've had the cowl off and on, top 
and bottom, at LEAST 30 to 40 times.  How much time did I save by not 
redesigning it to fast-open?
How about some tips on modifying our projects for maintenance --dos and 
don'ts--?
Terrence
N211AL
13 hours... cowl off again! and header too, to modify the failed quantity 
gages.


----- Original Message ----- 
From: "Tom Gourley" <tom.gourley@verizon.net>
To: <lml@lancaironline.net>
Sent: Monday, August 03, 2009 06:53
Subject: [LML] Build with maintenance in mind


> This is a suggestion brought about by a problem I found on my plane and 
> the recent LML series on cowling fasteners.  When deciding how to build 
> something, like the cowl fastenings, coming up with some really slick 
> method is fine; as long as it doesn't make it a hassle to remove pieces 
> for maintenance access and inspection.  In my experience if the cowl, or 
> some access panel, is a pain to remove people tend not to remove it unless 
> they really have to; like the required yearly inspections.  If it's simple 
> to remove inspections are likely to happen more often.
>
> Case in point.  I currently fly a Rockwell Commander 112.  (Apparently I'm 
> trying to find out just how long you can make a Legacy project last, but 
> that's another story.)  A couple of months ago my A&P and I replaced all 
> four cylinder assemblies on the 112; high oil consumption.  (Another long 
> story.  I've got a lot of them.)  The 112's cowl is fiberglass and the 
> upper half is a snap to remove.  I can do it by myself less than 60 
> seconds.  With the top cowl removed you can inspect pretty much everything 
> with a flashlight and mirror.  For the first few hours after replacing the 
> cylinders I removed the upper cowl after every flight and did a visual 
> inspection.  After that I removed the cowl every 2 to 3 hours for visual 
> inspection up to about 15 or 16 hours.  The only problem found was during 
> the inspection after the first flight.  One of the nuts on a fuel 
> injection line wasn't tightened properly and we found a small amount of 
> blue stain from the 100LL on the injector line.  Easy fix.
>
> After 15+ hours with no more problems I figured everything was fine, but 
> at a little over 20 hours I popped the cowl anyway and took a look around, 
> and found a large oil patch on the bottom cowl.  The oily area was about 
> the size of a dinner plate and since the inside of the 112's cowl is rough 
> fiberglass it meant there was a pretty serious leak; one that wasn't there 
> at 15-16 hours.  A little flashlight and mirror work traced the source to 
> a fitting on the #4 cylinder oil return line where it goes into the 
> cylinder head.  I was able to tighten the fitting's compression nut almost 
> a full turn with just my thumb and one finger!  I don't like to think 
> about what might have happened if I'd put off the inspection a few more 
> hours.  (And yes, the other nuts were all tight.)
>
> Bottom line, frequent inspections are a good thing.  Finding a problem in 
> the hanger is much better than finding one in flight.  Build safe.
>
> Tom Gourley
>
>
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