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Author Topic: Apprentice repair. How to repair a fuselage break and other stuff (motor mount)  (Read 317 times)

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Offline Frank v B

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This post will cover the repair to new member Gerald's Apprentice fuse.  The motor mount and firewall also broke.

Below is a photo of the fuse as it looks with the break. Photo 2817.

The second photo is a fuse repair I did on the Club Trainer Apprentice about 3 weeks ago.  Photo 2818.

Frank


"Never trade luck for skill"

Offline Frank v B

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It is quick.

step 1- mix 5 minute epoxy.  I use round toothpicks to mix and act as braces. See photo 1
step 2- stand the plane on its nose and apply the epoxy to the front part of the fuse break.
step 3- put the two halves together and hold for a few minutes.
step 4- just before the glue sets, roll about 4-6 toothpicks in the 5 minute epoxy and push them into the break area on a sharp angle.  Make them bridge the break. See photos 2 and 3.
step 5- let it stand on its nose until the glue hardens.

Once the glue has set, snip off the protruding toothpicks with side cutter pliers.

Frank
"Never trade luck for skill"

Offline Frank v B

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Tail feather repair:

Photo 56- there was a lump under the plastic film of the elevator.
Photo 57- beans!

Will glue the film to the foam on the tail feathers.

Motor Mount repair.

Most of my repairs are handled in two stages:
stage 1: glue stuff together so it is in the right places and pointing the right way.
stage 2: reinforce everything once everything is lined up.

All glue used was 5 minute epoxy. (what else do I ever use?)

Photo 58- best described as a thrust problem with the motor.  The motor mount had completely snapped.  The clear plastic firewall was fine.
Photo 59- shows the breaks in the motor mount.  All 4 screws are still solidly in place.  The outer ring (with the screws) had broken in two.
Photo 60- glued the motor mount together so it was in the correct position.  Put washers on the screws to spread the load.
Photo 61- the broken ring glued in place.

Will let it cure overnight and then reinforce it with fibreglass and epoxy.

Frank

« Last Edit: October 02, 2020, 11:11:02 pm by Frank v B »
"Never trade luck for skill"

Offline Frank v B

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Next up: the cowl repair.

Buying a new cowl is sooooo like giving up!!!

Again I try to glue everything together in the correct place, then strengthen it with fibreglass.

Photo 62- 5 major splits in the cowl.
Photo 63- use clamps on the breaks that go to the edges- to hold the edges flat and together.
Photo 64- clamps in place. everything adjusted.
Photo 65- Put tape on the outside of each crack to hold the two parts together.  The tape becomes a mould where parts are missing
Photo 66- put 5 minute epoxy over each crack on the inside of the cowl.  Wet your finger and rub it flat.

Let it cure.

Total repair time for this stage- 15 minutes.

Next step- fibreglass cloth strips will be glued on the inside to bridge the cracks and strengthen it.

Frank
« Last Edit: October 02, 2020, 11:12:30 pm by Frank v B »
"Never trade luck for skill"

Offline Frank v B

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The cowl.  next day.

I cut fibreglass cloth into 1"x2" pieces.  As well, cut wax paper into similar sized pieces.

With the tape still on the outside of the cowl, apply 5 minute epoxy inside the cowl over the cracks, apply pieces of cloth over top of the cracks and overlap them.  Once all the fibreglass is in place, place the pieces of waxed paper over top of the cloth/epoxied areas. 
The waxed paper allows you to press the glass into the cracks and makes sure there are no air bubbles trapped. Once the glue has dried, remove all the pieces of waxed paper.  If there are any missed cracks, apply more 5 minute epoxy and more cloth until all the cracks are glued shut.

Photo 67- the cloth and waxed paper randomly glued over cracks and waxed paper placed on top.
Photo 68- pieces of glass ready for the second layer and covering missed spots.

F
"Never trade luck for skill"

Offline Frank v B

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Final touches... after some photo coaching by Andy*:

Photo 74- cowl with the black tape removed.
Photo 77- photo after wiping some white paint over the crack repairs
Photo 79- motor mount fixed.  Note the golden coloured wrap around the perimeter of the repaired mount.  That is Kevlar thread attached with 5 minute epoxy.
Photo 80- The spool of Kevlar thread.  Bought it at the Milton Swap meet.
Photo 81- finished cowl installed on the front.
Photo 82- bottom view of the finished cowl

Also done:
- straightened out the divot in the prop and sanded it smooth
- removed the broken spinner.
- replaced the broken nose wheel pushrod clevis at the servo end.
- attached the carbon rods to the stabilizer.

Done.

If new member Gerald could call me (416) 605-0707 to arrange for a pick-up.  I will meet you halfway to your place in Scarborough for the prisoner exchange.

Frank

* sooner or later he will give up on this impossible student.
« Last Edit: October 04, 2020, 10:07:52 pm by Frank v B »
"Never trade luck for skill"

Offline Frank v B

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  • TEMAC #: 141
  • Started Flying RC: 1989
Gerald Penz picked up his plane last night.  I even found a New-in-Bag Apprentice spinner which somebody donated last year.

Gerald should be good to go.


Frank
"Never trade luck for skill"

Online Andy Hoffer

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Nice job @Frank v B !  I'll bet you could use these techniques for squaring up leaning garages!!  ;D

Just pull the walls vertical with a backhoe, stick in some toothpicks, slather on carbon veil and 5-minute epoxy, and presto!

Andy

Offline Frank v B

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For those of you who do not understand Andy's reference to a leaning garage.... he dropped by last Saturday when a friend and I tried to straighten a double wooden garage.  It was leaning 4" to one side so the doors would not close.  When we finished we had cut the lean in half.  This Saturday we will achieve plumb!!... hopefully without Andy's guidance.... since he is off doing full size aerobatics.

Frank

"Never trade luck for skill"