Ron,
I have found the nuts on the cooler not completely tight on some occasions doing
pre engine run checks on new aircraft.
Normally the client has failed to seat the cup and fitting well before
attempting
to tighten and then snug the fitting, as they are concerned about overtightening
on the tank and cooler which can damage a fitting.
The oil cooler tightening is a bit of a concern as the hoses are pulling during
the tightening sequence in some instances. To make the whole process easier
in the shop I would slack the oil line, position the fitting and hand tighten
the nut. Wiggle the line and tighten some more. Difficult to do in place. I
drop my oil coolers as far as possible and do not use the 90 degree fitting
supplied
by Europa. I order a straight fitting for nearly all my clients to assure
an easy and CFC standard fit. By lowering the cooler well below the duct
top, I find getting to my nuts much easier and is a great help during servicing
and inspection as the fitting can be tightened and inspected below the duct
metal top quite easily.
Personally, I cut the handles of the wrenches needed to fit the cooler fittings
so one can get to the fitting easily and properly snug the nut. Special tools
for a special airplane I guess.
Once tight, wiggle the hose to assure there is little to no torque on the
fitting
and check the fitting again.
Apply torque seal paint as an indicator for inspection. I find the nuts on my
coolers do not loosen.
Note:
The 90 degree fitting supplied in conjunction with hose routing can cause a
loosening
torque that can pull the fitting. If truly concerned there are remedies
to help safety the nut.
1. The nut cannot be drilled for safety wire so one can use a Breeze
clamp shaped
to the nut flanges and tighten the clamp. Then safety the clamp screw.
Use the clamp worm fitting as an anchor then to safety to the other
fitting.
This is extremely difficult to do after the duct is installed.
2. Loctite can be used on the threads also.
Personally, because I use the straight fittings on my duct, I have found no
reason
to use safety wire or Loctite. My torque seal paint has revealed no movement
and on my 5 year removal of the duct and flush of my coolers, all goes back
together well.
I do use the "Breeze Clamp method" on my oil tank however as I use leaded AVGas
for fuel mostly and every annual, I pull and clean my tank to see the
performance
of my lead purging. I also have had my return line loosen one time in 15
years on the tank due to engine start and running vibration I suspect. Post
mortem revealed an oil line a bit too tightly bent so as to push on my fitting.
I was suspect of my fittings may be leaking so I "Breeze clamped them. Come
to find out the oil filler cap seal was poor. (Try to find just that rubber
gasket! Rotax wants you to buy a new cap!)
So to service my tank, clamps get loosened and refitted at least once a year and
the belts and suspenders clamp and safety wire is a confidence builder for me.
Trust but verify as they say.
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com
<owner-europa-list-server@matronics.com>
On Behalf Of D McFadyean
Sent: Thursday, December 24, 2020 4:32 AM
Subject: Re: Europa-List: B-nut loosening on oil fittings?
--> <ami-mcfadyean@talktalk.net>
I've had them loosen enough not to be obviously loose (still seemed tight) but
enough to enable air to be sucked in giving a jumpy oil pressure gauge reading
(needle repeatedly flicking down to about 5 psi below normal indication; a
mechanical
gauge used to check this was yet more violent). I think the leakage had
more to do with the machining accuracy of the ball fitting rather than the
complete tightness of the nut per se.
I've seen others' that were loose, but may not have been tightened sufficiently
after intervention (thermostat fitting).
Duncan McF.
> On 24 December 2020 at 02:43 rparigoris <rparigor@hotmail.com> wrote:
>
>
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> Hi Group Has anyone ever had a B-nut loosen on a Rotax oil system? I have some
external retaining rings I can push onto the radiator and oil tank B-nuts and
safety wire, but wondering if I need or want to do so? Thx. Ron P.
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