Seat & Belts - Finito

This blog covers the work to finish the ftont seat and belt installation

Overview
The motor trimmer was less than enthusiastic to modify the headrests and suggested the use plastic cover to hide the openings then showed a sample - pity he only had 1.5 and did not know what car they came from and the trip to the motor wrecker proved to be just as fruitful.

A pair of 3D models were created, sent to China for manufacture which arrived in 6 days ready to install and where primed, painted in Wyattl Satin Black for installation.

The next task was to cut the openings - with the head rests positioned they were marked from the slots cut in the back of the seat previously using a white fine tip paint marker. With the openings marked the back of the headrest was cut using a X-Acto #11 blade with the foam removed and then shaped using the Dremel Motor tool fitted with their small sanding drum. 

Next the front leather was cut with the X-Acto #11 blade to clear the plastic covers. To allow the headrest to be removed the plastic covers were glued in position using black acrylic sealant. With the cover's in position they were covered with a paper towel and weighed using two house bricks to flatten and hold them in their correct position until the sealant set.

This operation was repeated at the seat back openings using similar techniques.

Trial fit with seat covers installed in the front seat
Compare this to the photo in the previous blog
The foam dust at the top is from the sanding to prepare 
the openings and was hard to remove

Trial fitting the dog clips showed a number of small modification were required to clear the new covers.

Dog clamps

Crutch strap attachment

Lap belt attachment
typical both sides

Adjustable lumber support

Comment
Worked as planned and while the added weight of the full leather covering is an issue, the final appearance and that smell of leather is hard to beat. 

Was it worth - I think so...!

With all the bolts tight this is a solid as a rock for the addition of 
two pieces of aluminium tube. The seat belts just reached using 
the extended D shackles.

Seat Belts - Part 3

This blogs cover the installation of the seat belt and attachments.

Overview
Covering the ongoing work to install the seat belts.

Installation
Attachment's for the pilot's shoulder harness were fabricated from two [2] pieces of 0.040'' 2024-T3 secured buy reusing existing 4 mm pop rivets located in the main spar. Both plates were fixed into a single assembly using five [5] 3 mm pop rivets.

Pilots shoulder harness attachment
Note: slotted attachments

The pilot's shoulder harness will be installed as two separate runs to prevent the belts being trapped by the gas strut with quick release attachments allow seat removal. 

To ensure that the belt attachments are located about the shaft center, a spacer was machined from 2024-T3 aluminium bar and alodined. 

Co-Pilot shoulder attachment
Doubler not installed as this was when that error was noted

The rear seat shoulder harness attachment had its doubler fitted at the attachment point using five [5] primed S/S pop rivets for this attachment as it's the most loaded single attachment point with a 600 kg design load.


Note: Breaking load for a forged 6 mm shackle is 2000 lbs [900 kg]

Co-Pilot lap attachment
spacers are typical for all standard triangular attachments

As noted previously Bow Shackles prevent unwanted alignment issues and ensures the belts are tight as practical in an accident.

Co-pilots area showing belts, hydraulic runs to pump which is now located in baggage compartment.  The flap controller was relocated forward one station to provide better access at commissioning while allowing the seat belts to be installed

Comments
Doing it again slots would be used at the attachments points but in the end the biggest task was just to design a suitable method for the attachment for the shoulder harnesses and in the end, it's a happy builder.

Next task is to terminate the flap controller, finish cable supports and install flap controller and once done that is the rear compartment at the famous 80/20 point.

At least the co-pilots happy

Seat Belt - Part 2

This blog covers the installation of the front seat belts

Overview
Covering the ongoing work to install the seat belts.

Installation

Rear Packer

With the seat belt frame manufactured the next task was to fit the seat. After trial assemblies it was determined that a 6 mm packer was needed at the rear support to create a near perfect alignment. 

Packers were manufactured from 2024-T3 bar, alodined and fixed to the underside of the seat using 3M trim tape and for ease of assembly then M8 studs were installed after treatment with thread locker.

Pilots seat adaptor
Crutch strap attachment is now located 
at the rear adaptor

Shoulder Harness installation

The leather seat belt openings were finally cut to allow the shoulder harness to be inserted through the back of the seat with the shoulder harness split into two separate runs then attached to the main spar. With the belt entry location set the top head cushion was marked to be taken back to the motor trimmer to have openings cut allowing the belts through to the seats.

Note: This was not done at time of manufacture as there was no idea how this would be executed, that's why the holes were cut in the seat but not in the leather so any error could be hidden - lucked out

Dogs fitted to seat bracket

The seat frame was secured to the roll bar using 19 mm electrical saddle clamps secured with M6 bolts using holes drilled through the seat verticals on both verticials..

To restrain the seat at the top the bolts retaining the saddle clamps were to be used but once it was determined that these would cut the stitching another method was needed. 

Dog clamps were fabricated using 50 x 50 x 1/8'' x 6061-T6 aluminum angle cut 25 mm wide with two [2] conduit clamps installed around the roll bar spreader and fixed to the seat frame using M6 screws.

Placing a short leg on the inside face of the seat with the other fixed to the seat frame with M5 rivet nuts then secured with M5 x 20 screws.

Note: Legs of the dog clamps were shortened to 25 mm to reduce leverage at the attachment point

Factory seat attachment - use of a seat frame
prevented this arrangement being used

Comment 
Final task will be install the belts and headrest on their return with the shoulder straps sent interstate to have the buckles stitched to extend the straps as close as practical to the main spar.

Seat Belt - Part 1

This blog will cover installation of the seats belts

Overview 
The seat belts used are Christian 2'' aerobatic 5 point harness out of the the storage box.

Spinal Compression
This is a touch pad for the aviation governing bodies in Australia especially loads that result in spinal compression by the shoulder harness that must be transferred into the aircraft structure.

Got it wrong
Lucky boy...!

Note: The FAA requires a minimum 9 g design load with a 60/40 split is applied the lap and shoulder straps to estimate loads. A design load of 10g with a 1.5 safety factor was used in the basic calculations. 

Revised factory roll bar and lightweight seats

The current aircraft features new seats and roll bar design that address the issue. I chose not to address this issue before installing the roll bar as a lot of work was being done by the factory will be duplicated but the shoulders harness are now a unique issue to this project.

The supplied with this kit were manufactured from vacuum formed shells with a filler sandwiched between the two halves, well that my guess as when cutting through the white filler its smelt like an automotive filler, this method is used to create vanity and baths and appeared familiar to me. What this meant that the seat belt did not have a definable load carrying characteristics and if quizzed I needed a plausible defence.

Seat Belt Attachments

Welding a new spreader bar into the existing roll bar was examined but as it cannot be removed easily and a TIG welder in a country town is a hard to find, especially if they have to come a remote airfield for two small welds.

A shoulder support was developed consisting of two [2]  1'' x 1'' x 0.625'' 2024-T3 RHS riveted to an 0.080'' plate fixed to the existing seat bracket. A folded 20 x 65 x 0.080'' 2024-T3 angle was riveted to the top side to carry the belt loads into the RHS. The RHS frame was stabilized using the roll bar spreader and a commercial 20 mm saddle clamp. 

Finally the seat was bolted at four [4] places to the RHS using M6 rivet nuts installed into the RHS and fixed with Unbrako dome head screws using 1/8" x  30 - 2024T-T3 aluminum washers.

Shoulder support for pilots seat

The shoulder harness frame was attached to the main spar using two brackets fabricated from 0.08'' 2024-T3 aluminium sheet riveted to the existing frame with five [5] 5 mm od pop rivets.

Note: Building a seat frame was not the original intent but that is where it landed

Both lap belts were attached to the face of the main spar using existing mount holes at a rib attachment. Lap attachments were fabricated from 50 x 50 x 3 6061-T6 aluminum angle. Next three [3] of the 4 mm rivets were removed from the rib attachment. The centers were marked onto the angle and drilled, fitted to the spar then each hole was reamed using a tapered reamer and battery frill secured with AN3 bolts.

Pilots lap belt attachment to main spar

Finally the crotch strap was fitted using a tapped hole now located in the rear seat spreader with the belt feed through a slot provided in the seat. 

Note: The rear attachment was required as there was not enough length when attached at the front as previously decided.

Rear Seat
A slot was cut thru the bulkhead to allow a 22 x 3 mm 2024-T3 bar to be installed. This was fixed at the rear using 7 x 4 mm rivets pitched at 20 mm.  A 0.020'' 2024-T2 doubler plate was installed to tie the attachment to the rear baggage compartment bulkhead.

Shoulder harness stiffers baggage compartment.
Stiffeners fabricated from 0.020'' 2024-T3 sheet

and the channel is factory longitudinal member

The front bulkhead was reinforced using a fabricated 60 x 12 angle from 0.032'' 2024-T3 sheet. This was then profiled and riveted to the top side of the existing bulkhead with a 0.040 2024-T3 doubler located at the front to increase the bearing area and reinforce the exit point.  

A 6 mm stainless steel bow shackle is installed to allow attachment of the seat belt harness. A quick release attachment was fitted to allow removal of the seat with the shoulder harness.

Rear seat attachment lap belt

Both lap belt attachments were fabricated from 0.080  - 2024 T3 sheet profiled to the drawing and with a suitable offset. The completed brackets were fixed to the stringers using 3.2 mm pop rivets. This attachment is similar to the current factory attachment method.

After installing the baggage compartment cover the harness attachment were inserted then bolted together using spacers at the belt attachment. 

Harness attachment
A major problem designing any connections is eccentricity but in any mechanical structure we use thicker plates with aircraft it needs to be light as practical.

To allow the misalignment to be accommodated, forged 6mm bow shackles were fitted with a weight penalty of about 12 grams each.

Happy days !

Always look at the bigger picture before setting off
Spot the deliberate error!

To tidy up this mess it was decided to remove and create a new skin with the gain being it allowed access to finish the mounting of the battery and pump. Originally it was intended to mount the shoulder strap in a completely different manner but this change allowed the relocation of the hydraulic pump - more later

Comment
Rear seat will be removed when the aircraft fly's to provide access for adjustments to the propeller controller as is now located in the place of the hydraulic pump.

Its done - Its done - Its done
 have mountings......!

Co-Pilot Seat - Part 1

This blog cover the installation of the rear seat and mounting brackets.

Overview
The problem that required Installation of spreaders to the front seat was the same for the rear seat. 

The factory has now designed a new seats to address these issue's.

Installation
Two 50 x 50 x 6 mm pads were fabricated, lightened and alodined for the front rear seat attachments to lift the seat to the designers relative position to the front seat.  

Packers & studs

Both air-frame mounting brackets have 20 mm od mounting holes with factory supplied thick aluminium washers. This mounting method deals effectively with the seat mounting issues, two [2] 3 mm x 40 dia washer were fabricated for the rear attachments covering the M8 seat mounting inserts. 

All four holes in the seat were chased with a M8 tap and a trial fit undertaken.

One issue found from the trial fit was the loose packers, so they were fixed to the seat using 3M trim tape. 

Rear packer and factory retainer bolt & washer

Note: The washers located under the seat bushes to ensure they cannot be pulled through the mounting holes if concentric at assembly

The front mounting point was now fitted to the seat, aligned and the seat re-installed into the aircraft. 

After fitting the seat the position of the front mounting foot location was marked onto the floor plate. Using that marked position the bracket was re-positioned onto the floor and a scrap of 0.020'' aluminium used to transfer the rivet line was across the mounting bracket foot. With the bracket removed and using the first rivet outside the marked position, the next three rivet centers was marked onto the aluminium strip with a pen. Finally the lug was re-positioned and using the reference rivet the location of the next three [3] rivet center marked onto the bracket, then removed and then drilled 5/32''.

Setout strip

The three [3] rivets that aligned with the fixing points were now removed and the center rivet drill 5/32'' with the bracket re-installed using the center hole secured using a 4 mm cleco. 

Using a long series 5/32'' drill all four [4] outer holes were drilled then the mounting bracket was riveted using three [3] x 4 od x 8 mm pop rivets at each side.

Note: Picked up all the existing 1/8'' rivet holes using this technique

The seat was refitted and the practicality of bolts to secure the seat was now called into question, this resulted in four [4] x M8 stud begin installed and another trial fit undertaken. 

Note: The geometry of the front studs required keyhole slots to be filed at both front mounting points 

A final check fit proved that the studs with a M8 nut and spring washer were a good decision as it makes installation relatively simple.

Rear seat mount and attachment for crutch strap [alodined angle]

The crutch strap mounting was profiled from 50 x 50 x 1/8 6061-T6 aluminum angle and bolted to the rear seat mount with two [2] x AN3 bolts and nylock nuts. 

Comment
The studs are now installed in the front seats as they are maintenance friendly and overall a lots less work than the front seats. 

Seat Upgrade

This blog covers the upgrade to the factory seats

Seats
A concession to the military theme of the cockpit is the leather covering of the seats with a upgrade to the comfort levels.

Both seats have been covered all over with leather, this was done based on the advice of the motor trimmer as it avoids the issues of the securing the edges to the rear of the seat as done with the factory covering, so the shell is covered all over in black leather with a felt liner fitted to the interior seating face.

The seating face consists of three [3] separate parts - headrest / back - seat cushion - front leg support and are held in position with Velcro strips fitted to the back and inserts as required. In addition an adjustable lumber support is incorporated into the back cushion secured by the Velcro strips fitted to the seat back.

The lower seat cushion has a high density heat forming foam sourced from Aircraft Spruce that provides better butt support.

Seat cushion

Comment
Passed the floor mounted comfort test and the smell off leather cannot be beaten.

Pilots Seat - Part 2

The front bar was drilled and tapped to allow future installation of the crutch strap. A set of four [4] holes were drilled to suit M6 grade 8.8 screws to allow mounting of the seat using four [4] M6 medium length rivet nuts inserted into the longeron, these were chosen as they provide a larger head on the underside at installation when installed.

The original slotted holes for the bracket mounting were filled and dressed.

At this time upgraded drawings for this area were received from the factory and builders are advised to refer to the latest drawings. The work described had been completed before the drawings arrived for the affected area.

Latest Drawings from Flying Legend

Inserting Rivet Nut
Block required to initiate closing of rivet nut

Rivet nut's installed
Two new ones added at the location shown on factory drawing.
Middle nuts from original install at factory bracket locations

Seat Bracket installation
Bolt at center of bar for crutch strap

All parts were painted satin black using Wattyl Super Etch Black and Machinery Grey for final installation of rudder pedals, foot supports and the seat. The seat required many, many reinstalls to check position before drilling holes and in all took a full weekend for that task and bracket preparation.

Pilots Seat - Part 1

A trial assembly of the seat showed that the seat would not just be a bolt in exercise. A quick call to the factory confirmed that the manufacturer was having problems with accurately inserting the attachment point's in the seat shell. While the seat can be installed it was not square enough for this builder, even with the brackets adjustment maxed out. 

This required a rethink.

As the problem was attachment position in relation to the brackets it was decided to break that connection. A piece of 2'' x 1/4''  2024-T351 aluminium was selected to allow the necessary countersunk screws and tapped holes to be installed. The first task was to define the relationship of the mounting holes to the seat body. Tape was located across the base of the seat using the molded crease line and a center-line was established and the bars located off these center lines.

.

Locating the mounting bar

Mounting Bars

The bars were removed, drilled, countersunk and fitted to the seat shell using M8 X 10 countersunk Unbrako screws.

The next task was now to locate the seat in relation to the air-frame. This took a number of fitting with the brackets clamped to the longeron and resting the seat in the fuselage.

Seat Location

Stick Location

Seat aligned about stick center-line

A length of M6 threaded rod was inserted into the pilots stick using the front stop mount with the center of the cushion marked with tape as shown. The rod was centered by measuring its location to the frame. 

The back of the seat was positioned 185 to 190 mm from the side of the fuselage placing the side of the seat cushion at approximately 200 mm from the outside edge of the frame using the bulkhead as the reference between both sides. A final series of visual tweaks using the rod and center line on the front of the cushion finally located the seat. The first set of holes was transferred using a felt tip pen from the brackets to face off the front bar. With the seat removed both holes were tapped M8 through.

The bracket were mounted using M8 x 10 Unbrako cap head screws - reinstalled as per the above and the final holes marked on the rear bar. With the seat fully bolted to the frame the final check confirmed that the seat and bracket were in line and square to this builder satisfaction.

Brackets Mounted
The seat brackets inside face aligns with the inside
face of the fuselage longeron