Motor Mount Assembly & Engine Mounting


The engine mounting or Lord anti-vibration mounting plate is a rather straight-forward and simple installation with some drilling involved.

NOTE: The AN525-832R10 screws used to hold the rubber Lord mounts that come with this kit are 8-32 screws. An 8-32 screw has a diameter of 0.164", where a 5/32 (drill bit size shown in the manual) hole is 0.156. Therefore, an 8-32 screw will not fit in a 5/32 hole. It is recommended to use the correct "numbered" drill bit size of #19.

The 447's engine Lord mounting plate has a semicircle cut out of the front, bottom or fuselage, bottom side of the plate which faces the engine mag..


Drilling For & Mounting Rubber Lord Mounts

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The Lord anti-vibration plate and assembly comes pre-drilled to a point. The only holes needing to be drilled are the 4 ea. rubber Lord mount retaining holes for all 6 rubber Lord mount.


For best results, it would be recommended to use a drill press as a hand drill sometimes wanders off center or out of perpendicular.

Use a rubber Lord mount as a template in the large hole to locate the small bolt holes. Drill the first hole using a rubber Lord mount as a template, then insert an AN525-832R10 screw to hold the rubber Lord mount in place. Drill a hole on the opposite side and insert another AN525-832R10 screw to hold it in place, then finished the last two holes.

         
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Repeat this process for all six anti-vibration rubber Lord mounts until all six have been bolted into place. Be sure add the washers & nyloc nuts and snug them down before continuing.


NOTE: New Engine Mount For Rotax 503 Engine

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As of February 2005, QC has been shipping the Rotax 503 engines with the eight (8) Lord mounts instead of the six (6).

Drilling and mounting the Lord mounts are the same as for the eight (8) Loard mount style plate, just a few more holes.
         
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Mount Installation Sequence
Motor Mounting Plate to Angle Brackets

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The motor plate with Lord mounts will now be bolted to the engine. "PROPER TORQUE AS SPECIFIED IN THE ROTAX MANUAL" must be used on the 4 engine mounting studs and metric nuts on the Rotax block. Be sure to use "BLUE LOCTITE" on the engine mounting bolts. The metric nuts and lock washers should come with the engine and packed with the carburetor. Then the 8 ea. AN4-16A bolts that go through the Lord mounts can be dropped down through the corresponding 8 holes in the 2" angle plate.

         
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Mount Installation Sequence
Angle Brackets to Root Tube

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Work from "right" to "left".

Note that the two mounting holes toward one end in the 2" angle should be toward the fuselage, not toward the tail section.
1. Place the two AN5-52A, 5/16" bolts:
      a. Through the right 2" aluminum angle.
      b. Through one of the 1-1/4" square aluminum motor mount spacers.
      c. Through the two rear most mounting holes in the end of the root tube.
      d. Through the second 1-1/4" square aluminum motor mount spacers.
      e. Then through the left 2" aluminum angle.
2. Slip the two washers onto the bolts, followed by the two nyloc nuts and secure.
3. Attach the washers and nyloc nuts securely, but do not over tighten. The root tube should not be depressed more then 1/16".
         
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CAUTION: If the entire assembly is performed prior to mounting the engine on the motor mounting plate, this will leave no way to torque the 4 engine nuts.


Make Remounting The Engine Simpler
Add 2ea, 1/8" rivets through "L" bracket & square spacers.
From: Mike Harrison

 

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Once the mount is installed, you can install a couple of 1/8" by 1/2" grip range SS rivets through the motor mount angles into the 1-1/4" square spacers between the angles and the root tube. Two rivets per side will hold the spacers in position for future removal and assembly of the engine on the airframe without having to fuss with them again. We usually will do this mod with the entire engine and mounts sitting on the bench in the shop. That way, we simply have to hold the engine in place under the root tube and align the 5/16" holes just long enough to install our extra long phillips head screwdriver for temp. holding.

         
 

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Using An Engine Stand
Makes A One Man Install Easy

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Using an engine stand will make mounting the engine an effortless, one man job. Just place the handle of a hammer under the rear of the engine, roll the engine into place and just drop the tail of the plane until the root tube lines up with the rear AN5-52A, 5/16" bolt hole and slip the bolt into place. Then raise the tail just a little and the front AN5-52A, 5/16" bolt hole will line up, insert the AN5-52A, 5/16" bolt.

The stand used here was built on casters to allow moving the engine in and out from the root tube a breeze.


Mount Installation Sequence
One Person Install Procedure

Complete the above "Angle Brackets to Root Tube" procedure prior to following the "One Man Install".

The motor plate with Lord mounts will now be bolted to the engine. "PROPER TORQUE AS SPECIFIED IN THE ROTAX MANUAL" must be used on the 4 engine mounting studs and metric nuts on the Rotax block. Be sure to use "BLUE LOCTITE" on the engine mounting bolts. The metric nuts and lock washers should come with the engine and packed with the carburetor. Then the 8 ea. AN4-16A bolts that go through the Lord mounts can be dropped down through the corresponding 8 holes in the 2" angle plate. The engine with motor mount plate and Lord mounts can now be lifted up and the 8 bolts hanging through the angle plates aligned and allowed to go down through the Lord mounts. A nut can now be started on the middle bolt on each side and finger tightened up against the nylon insert--the engine will now hang by itself. Tighten all 8 ea. AN4-16A bolts through the Lord mounts, but do not over tighten.

         
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Mount Installation Sequence
Two Person Install Procedure

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This assembly requires two persons (or an engine stand). Assemble the Lord mounts to the motor plate, install the motor plate to the Rotax engine using proper torque on the four studs and nuts. Although the manual calls for Red Loctite, we recommend the use of "BLUE LOCTITE" on the engine mounting bolts. Install the two, 2" angle plates to the Lord mounts using the 8 ea. AN4-16A bolts and tighten. Lift the engine up to the root tube and install the two spacers and AN5-52A, 5/16" bolts. A long taper punch works well here to help get it all lined up and to take some pressure off.

         
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Mount Installation Sequence
Another Easy Procedure

It is a lot easier to install the complete motor mounts to the engine and then mount it to the airframe than it is to attempt to hold the motor in place and install all eight of those bolts through the lord mounts. Here's the trick: While holding the complete engine WITH complete mount in position for the root tube, simply install a long phillips screwdriver in one of the 5/16" holes. This will hold the engine in place while you install the bolts one at a time. You can also use a quick grip clamp to sandwich the angles in place for proper alignment for inserting the actual mounting bolts. That's 2 bolts versus 8 bolts. Much easier.

         
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NOTE: The two "AN960-516 LARGE AREA WASHERS" are used below the two rubber Lord mounts on the inside of the mount, toward the fuselage.


The engine install and wiring will be covered on another web page soon.


Installing With A Vengeance

Here is a photo of two guys lifting and attempting to install a Rotax 503 engine on this engine mount. However, I was told later they were hamming it up a "LOT". :-)


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