REFLECTOR: Lord Mounts
steve korney
s_korney at hotmail.com
Tue Sep 9 11:29:22 CDT 2008
Engine Mount (Lord) Frequently
Asked Questions
How do I take care of my engine
mounts
Where a component maintenance manual is available for a system, its
requirements take precedence.
General Comments
Bonded sandwich assemblies are natural rubber or specially blended
synthetic compounds bonded to two plates. The normal installation
requires four assemblies, each consisting of two sandwich mountings and one
spacer. Satisfactory performance requires that the spacer be
designed to the correct length to precompress each mounting to guarantee proper
positioning of the mountings. When properly installed, these
mountings provide excellent isolation of engine vibration, resulting in
smoother, quieter flight. Always order replacement mounting by the mounting
assembly number to insure the correct spacer.
Visual Inspection of Installed Mountings
At each annual inspection and at FAA required inspections of the
aircraft's engines, all mounting assemblies should be visually inspected
in their installed state while supporting the engine's weight. The correct
visual inspection procedure is as follows:
Inspect all bonded sandwich mountings for metal-to-rubber bond
separations, flex cracks, rubber deterioration due to exposure to fluids,
and mechanical damage such as cuts in the rubber surface.
Visually inspect all bonded steel parts for cracks and excessive nicks,
scratches, or gouges.
Inspect all nut locking wires for looseness and tighten as necessary.
When applicable, measure all drift indicators in each mounting assembly
for excessive deflection.
Whenever any of the conditions detailed above in steps (a), (b), and (d)
are found, remove the mounting assembly from the engine, disassemble,
inspect, and repair it as described in the maintenance manual.
CAUTION
Whenever the aircraft engines are cleaned during a normal
inspection, cover each mounting assembly to protect it from
contamination by cleaning fluids or solvents. This also applies to engine
lubricants. Should any such materials accidentally get on a
mounting assembly, wipe it off thoroughly as soon as possible with a clean rag.
Disassembly
To remove mounting assemblies from the engine/aircraft, it is necessary
to remove the engine weight from the mountings by the use of a
chain hoist or equivalent, and disconnect the nuts and bolts which hold the
mountings in place. In general, removal of one mounting at a time
can be accomplished, if necessary, without removing the engine weight from the
mountings.
Cleaning and Inspection
Wipe oil and dirt from bonded mountings, but do not dip in cleaning
solvents.
Steel bolts and spacers should be inspected for cracks or damaged
threads. Examine spacers for crushing of ends caused by excessive tightening
torque on bolt. Replace if either condition is apparent.
Examine bonded rubber mounting for oil swelling, bond or rubber
separation, and shear or compression set. Bond separation, oil swelling, or
flex cracks in the surface of the rubber is cause for rejection. The affects
of shear and compression set are determined by measuring the dimensions
shown in Figure 1. Reject parts which have an eccentricity greater than
dimension "A" or an overall thickness less than dimension "B" as shown in
Table 1.
Figure 1.
Table 1.
Mounting Series Number
Eccentricity Max. "A" inch.
Thickness Min. "B" inch.
J1552
0.05
0.29
J2245
0.06
0.45
J3049
0.07
0.71
J6113
0.05
0.39
J7401
0.06
0.75
J7530
0.06
0.75
J7649
0.06
0.75
J7763
0.08
1.02
J8381
0.06
0.75
J9555
0.06
0.75
J9612
0.08
1.22
J10533
0.10
0.80
J10776
0.10
1.01
J12165
0.20
1.00
J12397
0.20
0.86
J12454
0.20
1.30
J12799
0.20
1.28
J13051
0.23
1.40
J15199
0.40
1.60
J7763-34(BTR-II)
0.14
1.02
J9612-30(BTR-II)
0.14
1.20
J9612-32(BTR-II)
0.12
1.20
Best... Steve
From: gstull at tampabay.rr.com
To: reflector at tvbf.org
Date: Tue, 9 Sep 2008 11:22:16 -0400
Subject: Re: REFLECTOR: Lord Mounts
I work as an A&P. All production aircraft that
I've seen, including heavy jets, use metal self locking nuts. I've never
seen anything else used. Castle nuts and cotter pins may be used somewhere for
engine mounts, but I've never seen it
----- Original Message -----
From:
Terry Miles
To: 'Velocity Aircraft Owners and Builders
list'
Sent: Tuesday, September 09, 2008 8:09
AM
Subject: Re: REFLECTOR: Lord Mounts
Dave,
Steve,
In another note,
Steve Korney said I should have castle nuts and cotter pins on the engine
mounts. I think I would have used what came in the Velo engine kit, and
I have metal locking nuts on these bolts. I am checking with the factory
on that today.
My question is about
torque setting now. Would it be 38 ft lbs with the metal lock nuts or
with castle nuts? Would the different hardware change the torque
value? Thank you both for this input. I want to learn, and I
appreciate your help to me.
Terry
From:
reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of
davedent at comcast.net
Sent: Tuesday, September 09, 2008 1:26
AM
To: Velocity Aircraft
Owners and Builders list
Subject: Re: REFLECTOR: Lord
Mounts
When it comes to engine mounts I have always torque
the 7/16" bolts to 38ft lbs and have had very good success with them. It
looks like your mount bolt is not torque correctly. But may be just
fine. Just torque them to 38lbs and they should be OK. Make sure you
bolts are not bottomed out. Like being to long. Also that the
spacer is also installed.
Remember also that most rubber products get harder
with age. In the environment that our engines run in I wouldn't keep
them more then eight years. Even less it they start cracking.
Believe me there is a difference between
manufactures of mounts as well. You get what you pay for.
Also keep solvents and oils away from them and keep
them clean. The harder they get the less effective they are and so being
more damage is done to the rest of the plane. Don't take rubber mounts
lightly. They do a lot more then just hold the engine in place.
Dave
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