Bits & Pieces No 9

This blog covers a number of small items overlooked in previous blogs on the wings

Main Spar Riveting
The spar laminates for the main spar have to be closed as tightly as possible for riveting, to do this screwed type Clecos are required.

Cleco Fasteners PLHN Series

The factory 3.2 mm holes are to be enlarged to 5/32 [4 mm] using a tapered hand reamer and battery drill. Starting with every hole fitted with a 3.2 mm Cleco from the tip, a Cleco was removed, then the hole reamed and a 5/32 Cleco fitted. 

Once enough were completed these were then replaced with the screwed Clecos. Finally these were remove one at a time and replaced with a 4 mm pop rivet.

Installing these required a little care as if they are not installed correctly they will pull through, this was found out early. 

Screwed Cleco was fitted by first extending the barb to its full length, inserting, next the outer sleeve was drawn back up by hand until the barb made firm contact with the spar face, finally, the nut was run down to a hand nip.

A ratchet ring spanner [shorty] was used to torque up the Cleco to create a firm grip.

Note: To do this the ratchet spanner was held close to the ratchet to prevent over-torquing

Wing Walks
The first point to note is it was not intended to flush rivet this area of the wing but when sitting in front of a warm heater with a pile of skins and a hand dimpler that master plan evaporated mentally and so that is that. 

On examination of the top hat supports, when dimpled, the small available edge distance provided evaporated so a new problem stuck up its ugly head. To fix this a 0.020'' packer was fabricated and new attachment method devised using more rivets. Once the fabrication was completed It was realized that a centre packer would be required, one was fabricated from the same aluminium sheet with an additional row of rivets added to secure it to the top skin.

Nose wing walk and attachments

Faced with the same problem at the other side a large enough piece of aluminium was sourced to make a once piece packer/attachment. 

Note: The edge distanced here were tight than theoretical but even if the holes are correct centerline the aluminium stiffeners plates take 3.5 mm of the available distance, doing it again this builder would examine placing these on the outside of the ribs to regain 3 mm on each side - it would help.

Fuel Tank Installation

The last two skins should have not been riveted to allow installation of the fuel cap adaptor seen below after the tank is installed. This procedure is noted in the new kit notes and it was all part of the builder's mental plan but in the excitement of riveting was lost.

The installation of the fuel tank neck seen in the upper right-hand corner created hours of fun to install along with the prerequisite mess, cuts and bad language that such tasks create. 

Note:  A word or warning to place notes on the panels when thinking of these things would have avoided this issue.

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Bits & Pieces No 8

This blog covers a number of small items overlooked in previous blogs on the wings / flaps

Aileron's
Both ailerons were checked before closure and meet the minimum engagement but at this point, it was noted that access to the rod end mounted to the bell-crank would be difficult to access to replace the rod end bearing.

Note: The minimum thread engagement is 1.5 times the major thread diameter - Aurora Bearing Company. 

The factory advised that an additional access hatch would not be required but the words of Kel Gore [Great LAME, now gone] echoed in my head "Cut one now because if I have to, it might not be so pretty". With those wise words, a cover was installed onto the inside face of the skin, secured with 6 x M3 rivet nuts with another cover was fitted externally using M3 x 12 pan head S/S screws. 

If needed, all that needs to be done is drill a 90 mm hole at the centre of this assembly.

Note: The bellcrank has been redesigned and relocated on the new models, this is no longer an issue.

Flaps
The attach brackets were fitted using 4 Dia x 13 multi-grip rivets using the pre-drilled holes on the outside rib, all four [4] holes were reamed to clean them for riveting. 

Four [4] rivets were driven into their mounting holes using a small socket and then pulled using the small rivet gun.

Countersunk Riveting
All holes were dimpled using a simple hand tool, while not ideal it proved to be cost effective. 

To achieve the best possible finish when fitting countersunk rivets, it has to be pressed into the dimple using the rivet gun with the centre-line of the Pop Riveter as perpendicular to the surface as possible before pulling the rivet. 

Stringers
The top and bottom stringers were secured at both ends using a T shaped clip to place the stringers face flush with the top side of the rib. The clips place the stringer flush with the top side of the skin, in particular, were a rib and two skin meet creating a 0.05'' thick attachment point.

The mounting faces were coated with black polyurethane adhesive/sealant at assembly to help ensure a tight assembly when riveted. 

Checking fit before fitting

To prepare to fix the stringers a centerline for the stringers was marked along the outside of the skins, next the rivet centres were marked starting by marking 20 mm from the centre line of each rivet line. At each bay, the distance between each mark was measured, divided by 40 and corrected to a whole number, finally, the centres marked. In most cases on this aircraft, this worked out to be between 38 and 40 mm across all 5 bays.

This operation is required to be undertaken at the top and bottom.

Note: A cheap compass with a fine line felt pen was used to mark the centres.

Next, all holes were drilled and a centre line added along the full length of the stringer. With the stringer installed is was manoeuvred over one of the holes at each end by sighting the line through one of the drilled holes, a hole was drilled and clecoed, this operation was then repeated at the opposite end and finally at the centres the centre of the line.

Once happy with the locations of these 4 holes all holes were matched through the stringer then the skin/stringer was dimpled and finally the skin/stringer prepared for final installation

Note: This operation is criticial, there can be no errors

Fuel Lines

With all the fuel lines installed they were all tested with air pressure to check for leaks. While most of the key points have access hatches it would be better to rectify issues before the skins were fixed. The pressure regulator on the compressor was lowered to about 10 psi and all open ends were sealed with plugs and the springs removed from the return check valve allowing a full system check. Each joint was checked by spraying with detergent/water around each joint while checking for any bubbles, all joints passed.

Pressure testing lines

What's wrong in this picture?

After completing the 3.2 mm riveting on the starboard wing and then working on the port wing a large OMG was noted. 

The last two skins should have remained un-rivetted at the topside to allow installation of the fuel cap adaptor. This builder had started blindly building an aircraft not assembling an aircraft. This procedure is noted in the new kit notes and the builder was fully aware of this, in fact, it was all part of the mental plan. 

To fix the issue an area of skin was de-riveted and some careful aerobatics performed to install the adaptor and connect all the aluminium pipes for the static line. This created many hours of fun along with the prerequisite mess, blood and incantations. 

Note: BEWARE and think when you have a rivet gun is in your hand.

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There will be more little bits to tidy up