Farings Rear

This blog covers the finishing up of the factory rear fairings.

Overview
With the painting next the rear fiberglass was finally dressed up and installed with the correct screws along with all those final adjustments.

Installation
The lower rudder fairing lights were connected via a four [4] pin plug mounted onto the first bulkhead after the fin attachment. To do this the cable in the fairing was drawn out and connected to the plug and then feed back in into faring then the faring was secured with a  flat head M3 screws.

The elevator faring were next and again secured with the M3 pan head socket head screws with the rudder stab fairings fixed with flat head phillips M3 screws.

Next was the dorsal fin here a couple of holes were re-established using a hole finder and after a series of adjustments it was screwed to the back of the fuselage using M3 flat head screws.  The connecting cables from the the stab and trim tab had previously been connected and it was a matter of checking and fixing the dorsal fin.

Finally the rudder stab fairings were installed. As these have to be removed at the 100 hourly to inspect my nick in the spar they were fixed using M3 pan head screws with an incorporated washer. The starboard faring required some more modifications at this time as it did not fit a cleanly.

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Note: All Rivet Nuts were re-tapped with a M3 tap to improve screw installation and avoid cross threading  

Fixing holes
Some of the holes had to be relocated, tuned pick a word this is one reason floating nuts exist. When required the correct center was marked onto the surface with a biro in the form of a cross. Next a small amount of Plasti-Bond was mixed and the hole filled then a strip of peel applied across both sides and the mixture squeezed between the fingers and set aside to cute.

When cured the new hole center was re-established and drilled with a 2.5 mm drill before sanding. Once shaped the hole was enlarged with the Dremel motor tool as described previously.

Priming
With this done they were removed and all holes in the fiberglass enlarged to about 3/16'' using a conical grinding stone found in the Dremel kit, this gave a clean hole that could not be achieved with drills. 

All fairings were primed using rattle pack bumper bar primer and left to be sanded just before painting

Comments
With the rudder and elevator stab fairings I would not remove the waste to the factory line just straighten both edges equally on both sides as the extra material would allow the fixings to be installed in a flat area the faring. Allow the faring to lie naturally as mine needs a push and shove to line up as pressure was applied before drilling mounting holes.

Note: Pressure was applied when drilling the hole to flatten out the curve and the movement when tightening up the screws created variability creating hole movement, in fact they fit differently every time if only a little. If riveting consider fixing the lower flange and then drill and fix the upper the upper.

The rivet nuts are a mixed blessing as without them the M3 large head screws could not have been used but they make the installation the holes more difficult. There biggest downside is the hole locations are more critical even with 5 mm hole but I was thinking floating nuts when doing the hole filling.

Pop rivets would be the quickest but there are reasons on this project and screws do allow you to adjust pressure obtaining a neater fit.

Above all make sure you mark out the ribs and spar before drilling.



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Elevator - Upgrade

This blog covers the work to install stiffeners for the elevator bell-crank and discovering a hidden error.

Overview
Flying Legend asked me too install two [2] angle stiffeners at the rear bell crank which are now incorporated into the current air-frame, after inquiring on method they advised the best way was to remove the elevator stab. 

Installation
The first task involved removing the fairings, rudder, fin post and to expose the deck plate. 

All pop rivets were then removed followed by both deck plates and finally the bell crank to allow installation off the new stiffeners plus installing bushes into the bell-crank. All the new brackets were alodined and a trial fit showed the rivets on the original brackets attaching the bulkhead and stringers would now foul, so new brackets were required.

These were fabricated from 0.040'' 2024-T3 to allow countersunk rivets to be used which solved all the interference issues, these were alodined, riveted into position and another trial fit undertaken.

Note: This was an upgrade and the current air frames are fitted with these components

With all problems now solved the bell-cranks were reinstalled and it was at that point the rear spar attachment came into clear focus - one mounting hole was a figure 8 and the other only slightly better.

How 
The cause was forgetting that the factories had pre-cut in the attachment point through the deck plates at the stab installation, so both deck plates were clecoed back into position until that day.  [see below]

Why

As delivered

Many months passed assembling the fin, rudder,stab and elevators then finally the time arrived to install the components.

With the deck plates in position and displaying blank flanges visually reinforced a decision to level the tail plane so holes were marked onto the flanges allowing the components to be matched drilled after levelling the stab .

Note: These plates were riveted in position before commencing the match drilling further compounding the error

Santos from Flying Legend's insistence on removing the deck broke that error chain - this issue was not detectable, as both external holes appeared perfect and no inspection at the end of this project would have picked it up.

Note: The factory manuals have been upgraded  since my purchase now supplying assembly instructions based on the factory's own manufacturing procedures, The rear attachment requires it to be reamed and bolted up. 

Extract of information from new manuals supplied with kits
these are very detailed and cover the correct sequence of assembly 
with notes, 3D images and photos where required.

PRM = "Please read manual"

Fix
The first task was to remove the the stiffeners attached to the bulkhead and they had been solid riveted. Without putting too fine a point on it, many hours were spent removing these six [6] rivets with the final method required the flared end to be ground back using a Dremel Motor Tool and drilling holes through the rivets until the reinforcing plates could be freed.

Note: On examination the rivets were fused to the bulkhead material at their junctions  - interesting

With both plates removed the front plate was salvaged to be used as a drilling template. New plates were cut using a scroll saw and finished using a combination of power sander and hand files. Finally all edges were then polished using 400 grit aluminium open cut paper. 

The factory they sent photos of the current installation for clarification and it showed the rivets were now five [5] off per side and all in a straight  line - done - scrap the first one. A quick referral to the new manual and drawings allowed a new profile to be developed.

New stiffeners - red stuff is blood - mine 

Stiffener finally in position
A packer [2 mm] was placed under the lower attachment point

Current factory installation

So more sawing, filing, sanding and alodine treatment  there was a new set of stiffeners. The  bolts were fitted with clecoes in the original holes, finally all the rivet holes were drilled to 5/32'' to ensure clean holes. Not having a riveter Steve from the hanger down the row stepped up and gave me a quick lesson on riveting solids.

Note: This was done twice as I was not 110% happy with the first brackets and decided to upgrade to match the current factory arrangement as it allowed better access for riveting than the original shorter plate.


All swaf was removed and the stiffeners reassembled and the rivets installed.

Steve - Rivet Gun for hire
Thanks

Comment
When this blog started it would cover the good and bad this had the potential to be bad.

The rear attachment was upgraded with the fin attachment stab plus the work described.  Thi simple error created 30 hours plus in rework, re-manufacture of plates, fitting and refitting - hand work combined with the fear of compounding the error is not a fast way to work.


Closing this chapter a line from Forrest Gump comes to mind "stupid is as stupid does" -  so God is forced to cover stupid -  this would have never been seen by any inspection - I mean never.

Stupidity is not a excuse

Elevator Hinges

This blog covers modification to the elevator hinges

Overview
As mention in a previous blog don't drop the aluminum inserts supplied with the kit - I never found the one I dropped but no issue, have one machined.

As small things all take time and a new bush was eventually machined with a 3/16'' bore, however it was discovered that the bore of the factory bushes was 5 mm and checking at the hangar revealed the machinist was correct. At this point the elevator was removed and all the stab hinge points drilled out to 5 mm.

Aircraft Spruce
Part #05-2500

While all the parts were disassembled it was decided to lubricate the spherical bearings with 3 : 1 oil, then pack with grease and to protect them from dirt ingress, aluminium bush's Seal-Its were ordered from Aircraft Spruce.

Each aluminium bush's flange was step machined to create 0.63'' dia x 0.025'' deep lip with the seal fixed over that lip using Loctite Black Max ACC and set aside to cure. 

Spherical bush rotated to allow oil and grease to be added

Parts ready to reinstall

Note: Each seals lip is packed with grease at installation.

Elevator hinges installed ready to remount

Note: Bolt thread will be trimmed to match AN3 bolt

Installation
Starting at the starboard side with the elevator level the hinge with seal was inserted into the stab brackets the a M4 screw slipped through to secure the assembly. The next one was inserted by springing the stab hinge with a soft podgy and inserting the next hinge and seal. 

This was repeated until reaching the port side when the first M5 Unbrako cap head screw was fitted. This proved to be a task as it had to be done using two fingers only in a small opening.

With all the bolts installed they were secured with M5 nylock using a shortened hex key and spanner.

Comment
It would be best to use AN hardware and the factory has been notified of the issue.

If installing seals again the bushes would be machined from mild steel with the step for the seal machined in one operation. It proved to be very difficult to center the very fine step required on the existing bushes.

The lubricated bearings were noticeably smoother and the seals will help keep out grit.

Elevator Install - Part 6

The elevator must be installed on the stab before the rudder can be installed as all practical access will be lost.

Wiring

The skin on the port elevator with the trim was not been fully riveted allowing the cable from the trim motor to the fuselage to be installed and secured correctly. A maintenance loop was stored in the first bay with oversize nylon clamps allowing the loom to slip through while supporting the cable away from the metal.

Cable supports fixed to lower skin

The cables were mounted onto the top side of the turtle deck using nylon clamps and stainless steel mounting brackets. These will be covered with the dorsal faring which will be fixed with M3 counter sunk screws and riv nuts to provide future access. The trim tab will be accessed via the side faring which will be secured in a similar manner.

These were also made removable to provide access to various points for future maintenance of all types.

Note: Doing it again I would have moved the connections to the elevator cover to allow access via faring for maintenance.

Cable connections

Fitting Elevator

All the necessary AN3 bolts and nuts were assembled and the elevator then fitted to the main spar. All of the bolts with little force required to align and insert the bolts through all three components.

Comment: Fitting bolts in this bolts here is an extreme finger sport but a long time ago, the tool below was purchased for this task. I have no idea what its called or where to get one again but if you see one, get hold it by all and any means available.


A bolt is loaded as shown and the tool allow's a bolt to be inserted with relative ease in tight places like rudders, elevators and ailerons.

There a a few more checks to do and a couple of small jobs then the rudder stab can be reinstalled.

Elevator Finito - Part 5

Note: The series of tasks photos used are not in chronological order.

D Nose

The material used to manufacture the D Nose distorts easily and that's why it was placed under the top skin as my attempt to achieve a flat skin resulted a puckered look but there was a positive as packing was required to align the skin to the mass balance.

Comment: Keep the skins is a safe place and do not separate from factory packing until needed. Handle as little as possible as this aluminium is very soft and will damage easily.

With the D Nose skin matched drilled  and cleoced the elevator assembly now removed and the remaining holes drilled then the D Nose was removed. All swaf was blown out and the D Nose de-bured carefully then primed on the inside face, top edges and allowed to dry.

The D Nose was installed using the factory M3 x 8 pop rivets. 

Mass Balance Faring

A misalignment at the top side of the outer rib for the mass balances meant that packers had to be cut from 0.020'' scrap as required. These were installed in varying lengths and combinations along the area affected with the goal to taper or average out the misalignment and prevent a deformation if the skin was riveted to the face of spar. 

Packers Port Side

There was no science just plain old "suck and see"  based on if it looks good it is good.

At assembly the various combinations especially the single hole packer had a drop of Loctite 380 Black Max Super Glue applied and cleoced to dry.

Mass Balances

Next the skin for the mass balance was trial fitted to check alignment to the tip faring. The mountings for the mass balances had been installed previously in the assembly following the factory drawings. Due to the thickness of the flange each hole on the inside face was counter-bored with a 5.5 mm drill to a depth of 3 mm to allow the factory rivets to be used

Checking balance with mass weights
Note: A small amount of the rib is marked
for removal to clear faring

When installed it was noted that the elevator assembly did not achieve positive balance, so an extra 60 mm OD x 7 mm thick washer was added to both sides which meant the M10 lock nut had to be placed on the outside of the outer rib and tightened. 

Factory installation

The mounting blocks for mine were installed before this was noted by the builder. A existing hole was enlarged to accept the 10 mm shaft and this allowed four [4] pop rivets to be used as it would be bad news if a weight ever broke free. I will speak to the factory about the required balance and if more is required it would be done with led shot and epoxy. 

Adjusting flanges

Packers after riveting

Extra weight added

Assembled mass balance faring.
Note: Tips are ready to install and the skin was 
fitted as a final operation with the tips

Fitting Fiberglass Tips : Stab

With the elevator re-mounted and chocked into alignment allowing the tips fairings to be installed and aligned with all the mounting tab's for the fairing's installed previously. 

Starting at the port side, the tip was sanded slowly until it look right - it was that scientific. All sanding was done using 80 grit paper on a flat surface at the start. A taper was required and it was started on using a 300 mm disc sander with a 125 grit and finished using a sanding stick and 80 grit paper.  

Fitted then marked and sanded again and again till the correct look was achieved. 

Note: One side had to be sanded generally to achieve the correct appearance - these were not just a square sand. 

 

Port tip ready to install
note tilt

Once satisfied the fiberglass faring was match drilled to its tabs and fixed with M3 x 6 counter sunk pop rivets.

Port tip installed

The starboard tip was approached in the same manner except the location of the outer tip was used as a reference using a marked stick to transfer the location from the port to the starboard side.

Note: The fuselage was level for this task allowing the floor to be used as a fixed reference. After riveting the end of these tips are a absolute weapon, care has to be exhibited when moving past them

Checking starboard tip location using marked stick

Fitting Fiberglass Tips: Elevator

The right line - following the red line

Elevator was chocked into it correct position for level flight allowing the tips to be aligned. After the first fitting it was decided that the end of the tip had to be opened to allow the tip fitting to begin and was achieved using a hand saw.

Open end elevator tip as it was
found it was to tight at the rear

The procedure was the same as the tips with the edges having to be sanded differentially to achieve the right line. The best technique to determine how much to remove was to hold the tip hard against the top skin or bottom skin and rotate it till it contacted the opposing skin. Check the line and if incorrect rotate the tip on the over size side into the correct position and then using a finger to feel the gap then sand the appropriate side - repeat and repeat.

Note: The amount to be removed was marked using a Sharpie pen and a finger as the guide to transfer the estimated amount to be removed to the faring - then sand - repeat.

With all these task's completed the elevator was removed again and the mass balances weights, tips and fairing skin installed.

The final task is wiring and this is for the next blog. 

Finito is Italian for finished

Elevator Alignment - Part 4

When Franco meet me at the hanger about the Tucano he commented that make sure that I aligned the elevators. The impression was that all the holes are drilled, "what could I align" as each elevator when assembled was quite ridged joined by a torque tube. 

Elevator assembly was simply a matter of bolting and riveting the torque tube using the pre-drilled rivet holes and nut plated installed in the elevator's.  When the alignment of the hinges was checked a distinct misalignment was noted but after packing and packing it was concluded that this approach was leading in the wrong direction, time to stop and think!

The Jig
What was needed was a jig or a fixed reference and that lead to the stab which is both rigid, straight and the elevator surfaces has to bolt to it.

Packer port side

A string line was run through the center of the four [4] hinge mounting holes and it was concluded that a 0.030'' packer was required behind the port outboard hinge to bring all onto the same center. 

This was fabricated and riveted on its center to the spar using two [2] 5/32'' pop rivets and when rechecked the string was on all the hinges centers. It was now ready to be used as the jig to align the elevators using the aluminium D nose to lock the elevators into correct alignment to the stab and fuselage.

Port Side check

Starboard Side check

Elevator Alignment 

With the fuselage level with the tail plane the assembled elevator was fitted onto the stab. The next task is to align the trailing edge of the elevator to the stab, this was achieved using another water level and a piece of lumber to hold the tubes into position. 

The elevator was twisted into alignment by placing an aluminium angle prop under the inboard edge while resting on a clamp with the extra 3 x 2 there as dead weight.

Starboard Elevator - Aligning & fitting D nose

Cessna D Nose

With the elevator level the D Nose was taped into it's correct location using duct tape then checked and match drilled at one end then the other, clecoed and rechecked. 

Note: The lower edges of both D Noses had been pre-drilled before installation with the folded edge a few mm from the face of the spar. Positioning the skin equally from the face of the face of the spar located the D Nose in the correct location providing the clearance for correct operation and a neat appearance when assembled. 

Comment: Keep the skins is a safe place and do not separate from factory packing until needed. Handle as little as possible as this aluminium is very soft and will damage easily.

The supplied skin has a large excess of material - do not trim until the mounting holes have been fully drilled.

My decision to place the D nose under the skin is based on the need to control the shape to match drill, its the same arrangement used by Cessna with the profile begin the same as the Tucano's. 

Finally a series holes were drilled, clecoed then the balance will be matched drilled on the bench for final riveting.

Port Elevator - Aligning & fitting D Nose

The procedure was repeated on the starboard elevator using the same reference point on the outboard edge. The inboard edge was ignored as it was leveled with the port side as the horn is a rigid connector of the two inboard edges.

The final task will be completed at the next secession but will require removal, de-burring and removal swaf and other tasks before re-assembly and riveting.

Elevator Hinges - Part 3

Before fitting the D Nose the hinges were assembled and installed.

All components are supplied with the kit but required assembly by the builder. The mounting angles are counter bored on the inside face to accept the spherical bearings supplied. As part of the installation are eight [8] turned aluminium spacers and they are easily lost - wire them together until needed.

Installing Bearings
Aluminium sheet is for protection when
driving the bearing

The bearings are a press fit and required a firm wack to install them. The edge of the bearing's were dressed using a points file by drawing it backwards around the rim perimeter to refine the rim. With the bearing inserted squarely on the opening it was driven using a 3/8'' diameter x 1/4'' drive socket placed on the rim and struck firmly with the 8 ounce hammer.

Once assembled the two half were brought into alignment using the 8 oz hammer. 

Note: A aluminium scrap was used on both side's for protection of the hinge.

Ready to assemble

The aluminium spacers are fitted at both sides using the 2 oz hammer. A couple were a loose fit and were treated Loctite at assembly ensuring that none lodged on the bearing. At this point wire up each assembly using lock wire as they can be lost and are a bear to find. 

The required AN3 bolts and washers were assembled and fixed using the previously installed captive nuts.

Elevators - Part 2

Before commencing assembly the captive nuts needed to be fixed onto the main spar. The operation began by enlarging the factory 5/32'' rivet holes either side of the 3/16'' hole to 1/8'' to allow rivet insertion. After drilling these are counter sunk to suit 1/8'' countersunk rivets with the captive nuts were modified as per the previous blog - 12 per side required.

When complete all captive nuts were fixed using the supplied 1/8'' countersunk pop rivets.

Note: One set of the holes are close to the flange to allow the use of even a small micro-stop if one was available. Trying to use only the cutter resulted in a nick into the metal which had to be polished out. 

This set of holes were counter-sunk using a 7 mm drill. This was done with the battery drill running at the minimum possible speed with extreme, extreme care. The clutch was set to just drive the drill.

Frame ready for skinning

Port Frame
Assembled the frame and fixed with the supplied dome head rivets.

Port side skin refitted and fully clecoed except to the attachment to the main spar to allow fitment of the D nose.

Starboard Frame.
Assembled the frame and fixed with the supplied dome head rivets. 

The skin was refitted and clecoed to the frame.

Elevator Trim

The unused portions of the ribs projecting from the skin were marked and the clecos from the first two ribs were removed once side at a time, the rib's are cut with aviation snips. The skin re-clecoed and the operation repeated on the other side. 

Modification: Refer disclaimer

Trim Tab Mounting

The factory supplied with this kit, two [2] folded 90 degree angles to fabricate the end caps that form the mounting for the hinge of the trim tab. Also supplied was 4 [four] plain ribs for the tab and a full elevator skin.

The folded 90 degree angles for the frame were prepared and mounted. The top angle needed more that 90 degrees and after correcting the angle  it was was curved by the process used - time to stop and think about it.

The conclusion was to begin again with new folded angles that were manufactured at the correct angle and had larger flanges making assembly less critical. 

Schematic's of the assembly scheme is shown below and is unapproved - refer disclaimer above.

Elevator Schematic

Elevator Trim Modifications
Two [2] angles were folded from 2024-T3 aluminum to match the opening profile at the rear of the frame. One was folded wider than the opening to be trimmed later. Both have a 20 mm flange to match the original.

Rib preparation

The flanges of the two ribs were modified as shown opposite with the final profile shown on the right hand side. 

The lower angle was fitted first with its overall depth reduced by 3 mm from the measured dimensions of the openings. Fitted the angle's 20 mm flange into the rib and match drill two mounting holes at adjacent ends using the skin and checked the alignment. 

Once satisfied all the remaining holes were drilled and the angle secured with clecos.

Two aluminium angle tabs were fabricated to suit their location and attached at each rib with 2 [two] pop rivets, The lower angle was secured to each tab [rib] with a single 1/8'' counter sunk rivet after dimpling. This allows the top angle to be fitted on top.

The upper angle was positioned above the lower flange and drilled using the same method outlined above.

Using a straight edge the bottom was alignment was checked, then using clamps, fingers and eye the lower angle [rib skin location] was adjusted into its final location. Particular attention was taken to ensure the line of the skin follows the correct line of the rib profile. It was a balance between a straight line and the rib profile visuals. 

Starting at the outer rib, drilled the first hole at the base and fix with a 5/32'' cleco, repeated the process at the opposite end then the center. This process created a single element that locks the top and bottom skins into their final location.

With a final check using a straight edge and eye, checked the overall appearance and when satisfied the last task was to drill the balance of the holes in the lower row then fix with 3/32'' rivets.

Note: The location of all mounting holes were marked using the drilling jig supplied by the factory using a felt tip pen.

The 3/4" wide piano hinge supplied with the kit was separated into its two components then one was drilled to match the rivets on the elevator at a 30 mm pitch to accept 3/32'' rivets. 

Positioned the hinge and match drill the skin and spar - fixed hinge with 3/32'' pop rivets.

This blog must be read in conjunction with this later blog - Hitting a Wall