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I have a few ideas for the instrument layout at this early stage but I tend to keep this sort of thing flexible, keeping my options open.
For the time being I’ll install the stock instruments in the central instrument panel.
I didn’t fancy the recommended glass fibre mounting brackets for the Fadec Display so I made these ‘Z’ brackets and fitted countersunk M3 Rivnuts in them. They are secured to the Instrument Panel with countersunk M3 Stainless socket head screws.
Here’s the rear of the Fadec Display. I’ve riveted a 12 inch strip of 1/2 in x 1/2 in reinforcing Ali angle down each side of the panel.
I’m looking at either the Becker or Transair round Radio and Transponder located in the central area of the panel. I’ll extend the top of the instrument pod upwards to accommodate an Artificial Horizon and a Directional Gyro. Present thinking is that I’ll mount the GPS on a fold - out mount half way up the left door pillar.
Here’s the first design template for an instrument layout on the Pilots Footwell Panel. The top two holes are Bearing Temperature - Secondary and Right Hand Tail Rotor bearing. Instinct tells me this one will take most punishment in the TR drive train. Second row is Fuel Pressure, Volts and Engine Revs. Bottom right is the hour meter. The area below the second row is obscured by the Pilots feet..
The holes were first cut with a 50 mm Q Max cutter then opened to size with a flap wheel
This panel may or may not be the final example. It’ll probably be painted.
Here’s the Microair Radio and Transponder alongside the Rotorway Digital Level for an idea of scale. The radio can be remote switched from the cyclic between two stored frequencies or through the whole stored memory of twenty five frequencies. The Transponder has Mode C ability if used with a separate encoder. Mode S is due to be introduced here in 2008 but Mode S units are currently twice the price of Mode C. I’m gambling that by the time Mode S is mandatory the price will have fallen to the current Mode C price. As I’m hoping to have my ship flying in 2005, I can see no point in paying for Mode S yet.
TRANSPONDER HOUSING
It has always niggled me that to change the transponder codes on an Exec means either reaching across with your left hand, swapping hands on the cyclic or always having a clued-up passenger sitting next to you. On the ‘Events’ page of this site is a picture of The Transponder in Ivan Bedfords’ Exec 90. 90’s have a wide sill moulding which has offered an excellent mounting position for a small square Transponder like Ivans or my Microair. The 162F however, has a much narrower sill moulding but I thought I’d still try to mount my Transponder in front of the collective.
Plan ‘A’ was to make a buck then a mould then a housing from GRP so I started with a block of Teak and machined a recessed face plate/mounting head.
I knew pretty-much where it would sit so I made a heavy cardboard template housing and taped it all together.
I duplicated the template in aluminium....
.....and screwed it to the head. It was all looking pretty good so I hollowed out the back of the teak block and decided to use it as the finished article. Teak is a very strong, close grained wood that can be machined to quite thin sections. Weight was a little more than it would have been in GRP but it saved a lot of work.
A Pilot’s Eye View. It will eventually be either Flocked or painted and I may yet remove a couple of the mounting flanges to tidy it up a little more.
TRANSPONDER AERIAL
I opted for a small ‘Sharks Fin’ style of transponder aerial mounted on the underside of the front tub on the passengers side. Position choice is a little limited because a Ground Plane in the form of a 12 inch diameter aluminium disc has to be installed on the inside of the panel.
The mounting face of the Antenna is, of course, flat and the tub is, of course, curved so I repeated the same moulding method I used for the Radio Antenna and the Strobe bases - a bed of filler on a packing tape skin.
You can clearly see the tub curvature moulded into the base. When it’s painted white it’ll be invisible.
INSTRUMENT PANEL EXTENSION
I’ve never been too keen on widening the instrument panel so mounting the transponder elsewhere left me plenty of room for the instruments I have chosen to fit on the standard panel. However, I quite like the idea of keeping the warning lights as high on the panel as possible so I decided to simply extend the panel upwards by an inch and a half. I couldn't see the point of making a completely new panel so I grafted on the extension with a backing strip and solid rivets.
I cut the top of the original panel level and guillotined a 1 1/2 inch and a 1/2 inch strip of the same material.
I drilled and countersunk both sides and fixed the assembly with seven solid aluminium countersunk rivets. The original warning light holes and the joint will be filled. The new holes are spaced for the regulation labels we have to use in UK.
The old warning lamp holes, and the seam have been filled with Epoxy putty and the whole area rubbed down with 240. Spot the joint.
INSTRUMENT POD RESHAPING
I had two options to make the Instrument pod fit the newly extended panel - either mould a separate extension piece and graft it on to the top of the pod or try to reshape the existing pod profile. I chose the second.
I started by slicing the panel into symmetrical strips with my panel saw.
The top of the moulding was surprisingly thick - 1/8 inch in the centre. This made it quite difficult to curve and twist the strips to match the profile of the panel so I carefully ‘thinned down’ the thickness of the strips on the inside with a sanding disc on my small angle grinder.
I was then able to pull the strips into position by gradually adding layers of tape.
I cut a paper template slightly larger than the shape of all the cuts and bonded in two layers of Chopped Strand Mat.
When the inside laminate had cured I ground away the original outside layer back to the new, inside layer, leaving the front lip at about half the original thickness
Here’s the most efficient GRP removal tool. A 60 grit Flap Disc on a small Angle Grinder.
Another two layers of CSM on the outside.
Dressed off and painted.
The GRP instrument pod is not actually straight from top to bottom so I put a matching dog-leg in the panel at the top of the Fadec cut-out. I simply beat my aluminium angle supports at the bend position until they stretched to the correct angle. You can see the black line and the beaten area.
I decided to paint the instrument panels Wrinkle Black.
Here’s the cut-out section for the Pilots side instrument panel. I cut away just what was needed for clearance around the gauges.
Here’s the assembled Footwell Instrument Panel. From top to bottom, left to right: Secondary Bearing Temperature, Tail Rotor Bearing Temperature (the outer one), Engine RPM (back up), Fuel Pressure, Volts, Hour Meter. I may change them around at a later date.
And the main instrument panel. Top to Bottom, Left to Right. Warning lights:
RED - Engine Low RPM, YELLOW - Landing Light, RED - Starter Engaged, GREEN - ECU1 (Primary) on, GREEN - ECU2 (Secondary) on, YELLOW - FADEC Error, RED - ECU1 (Primary) off, RED - ECU2 (Secondary) off
AIRSPEED DUAL TACH (Rotor speed and Engine Speed) ALTIMETER
MANIFOLD PRESSURE ARTIFICIAL HORIZON RADIO OIL PRESSURE
OIL TEMPERATURE SLIP BALL LOW VOLTAGE W/L WATER TEMP
VERTICAL SPEED INDICATOR
FADEC MONITOR/DISPLAY
FUEL LEVEL
LOW ROTOR RPM HORN
The Tach supplied with my kit is the latest version with on output for a Low Rotor RPM warning alarm. I’ve shopped around and purchased a few Piezo buzzers from Mail order electrical component suppliers but none of them have matched the power and volume of the one in the Robinson. The simple solution? Get a Robinson one. Here it is. Hugely expensive and certified but loud and, perhaps more importantly will be a familiar sound when I convert to my own ship.
It draws 75 miliamps current and I’ve yet to check if the Tach output is sufficient but I expect so. UPDATE. I understand the tach output is 200 ma so all’s OK.
I decided to mount the Horn in a small waterproof housing on the seat back just behind my right ear.
I made a moulding by simply laying up 3 layers of fibreglass cloth over an aerosol can lid on a piece of aluminium sheet.
When the lid is removed what’s left is a very lightweight ‘Top Hat’ moulding.
I marked out and drilled an aluminium template to drill holes for sound to escape.
Here’s the sounder, it’s housing and the drilled seat back.
Rotorway supply a pretty good set of three wiring harnesses. Most of the fly leads are too long for a neat installation but I decided to lay it all roughly into position first.
It looks a bit of a mess at first but things soon start to fall into place. Bottom right is the cradle containing the two ECU’s. To it’s left are the four ECU plugs and left again the Coil/Ignition packs mounted to the aluminium seat back panel.
With the main harnesses roughly in position I fitted the Seat Back and Footwell Panels. I then mounted the ECU cradle below and between the seats using countersunk screws and Tinnerman washers to spread the load
I cut away the ECU cradle around the installed DZUS fasteners that secure the battery access panel, viewed here from below.
This is a view of my seatback location method (described elsewhere on this site). The manual tells you to secure cables to the frame and seatback tubes with cable ties, ignoring the fact that the accuracy of the seatback panel location is critical to the correct fitting of every other panel on the ship. The thickness of a few cable ties can make a difference between a panel fitting perfectly and niggling misalignment. I made sure no cable ties were fitted where they could disrupt panel alignment. The rebates and clearance grooves you can see in my mound of filler here are for the Seat Harness Lap Belt mounting (right) and for cable tie clearance (centre and left).
The instrument panel harness has wires only for the basic instrument set. If you have any extra instruments (and everyone does) you’re on your own when it comes to wiring them.
I made additional Positive and Negative tails where I needed them by splicing into adjacent tails. I carefully removed 1/4 inch of insulation from around the wire then wrapped and soldered a new tail. Heatshrink then covered the joint.
The overhead switch Panel is supplied with only nine switches and ten fuses. I added a further seven switches and eight fuses. The main ignition switch is top centre. Either side of it are the ten pin, pre-wired sockets that were supplied with my Denali Headsets.
I linked the power side of the four new fuses on the right from one fly extension and the two banks of two fuses on the left with a supply each.
I added two extra 6 way plugs to the overhead loom. One for the headset cables to the radio and tone for the 6 other additional circuits - GPS, Nav Lights, Internal Lights, Landing Lights, Strobes and Transponder.
Everything’s in place and looking OK. I’ll probably flock the transponder housing though.
I mounted the Transponder Altitude Encoder (bottom left) to the inside of the main instrument pod shell, pointing forward. There are some calibration screws just above the cable. It should be easy enough to get to these with the Landing Light panel removed.
I keep refining the layout and repositioning the wires until I’m happy with it. Short pieces of Spirap keep local groups of wires tidy.
The main panel from below. Everything is accessible for inspection.
I just sat the overhead switch panel in position on top of the roof so I could connect up and get the cable lengths right. I added a cable support saddle to the panel just behind the key switch. The Headset cables are very fine and fragile. They’d break for sure if they are allowed to move around.
It occurred to me that it would be much easier to leave the switch panel on top. The only reason for fitting it on the inside, as far as I can see, is to hold the liners in place. I have no liners - so on top it is.
Here’s the Pilots Cyclic cables. There are three connectors here - Landing light switch, Engine Starter Switch and a three pin plug for the Radio PTT and Memory Recall.
I added a second bearing temperature gauge for the RH Tail Rotor Bearing. I don’t know if I’ll get any sensible reading from it but I reckon this bearing can potentially take more punishment than the others. We’ll see. I’ve ‘Spirap’d’ the cables to stiffen and support them. The rear plug is for the tail Navigation Light.
Here’s the alternator wiring...
.. and the strobe controller. I’ve earthed the strobe controller to the frame under one of the Tail boom bolt heads.
At this stage I’ve spent 56 hours on the wiring. I’ve used at least an extra 260 feet of cable, 250 small cable ties (most of which have been cut off again) plus a dozen or so more plugs and sockets than were supplied with the kit - and I ain’t finished yet.
After three or four attempts at routing the heavy battery / starter cable I finally ran it along the underside of the fuel pump mounting tube, exiting up to the starter by the oil tank.. Neat and out of the way.
Looking down on the transponder Ground Plane. A 12 inch diameter aluminium mesh disc secured with the transponder antenna fixing nuts and big washers to the inside of the front tub panel.
Here are a few details I thought worth mentioning - I wish someone had told me!!
- Solder doesn’t seem to be what it used to be. I haven’t done much fine soldering since my work on Concord, Nimrod & other defence stuff thirty years ago but I’m sure solder used to flow a lot easier than it does today. I reckon it must be something to do with the lead and flux content.
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Anyhow, by cleaning the soldering iron tip on a wet sponge and poking it in this little tin of tip cleaner/tinning compound before every joint I managed neat, clean joints every time.
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I was supplied with self-assembly BNC connectors for my Radio and Transponder. The preparation and assembly instructions are almost right but nowhere does it say that the gold plated centre pin is a ‘push and snap’ fit in the insulation at the centre of the plug. I wasn’t happy with the physical separation of the centre pin and the braided shield until I discovered the correct method of assembly. You have to push the cable hard until the centre pin ‘snaps’ into place. With the cable I was supplied the length of the centre insulation sticking out beyond the shield needed to be 10 mm instead of the 6 mm specified. It may be different with other cables however.
I’ve tried to make everything accessible and serviceable. I’ve installed plugs and sockets on components that may have to be removed one day. I’ve tried to label every cable for easy identification and troubleshooting and I’ve made drawings of all new wiring and sub assemblies. One thing I’ve learned from building cars and getting older is that I may remember what cable goes where for a day or two but a few weeks down the line I’m sure to have forgotten completely and I’ll have to trace cable runs the hard way.
These cable markers are made from a tough self adhesive fabric and come in an inexpensive pad containing 15 sheets. Buy two though - you’re sure to run out of the popular letters fast. UK supplier is Maplin but I expect Radio Shack will have something like them.
This is a Cable Tie Base. It’s self adhesive but you can screw or rivet if you need an extra secure fixing. Brilliant for tidying loose cables .
I needed a frame ground somewhere near the front of the ship so I tapped out the bottom end of one of the tub support welded bushes 5 /16 UNF and installed a bolted ring terminal - after removing the powder coat from the face of the bush, of course.
During my apprenticeship the phrase ‘Remove Sharp Edges’ was used constantly every few sentences on job sheets and machining schedules. I instinctively feel for and remove any sharp edges to this day, even on parts like this Plug Wire Separator. I know it’s only plastic but silicone plug leads are relatively fragile and I don’t want to risk scoring them.
Here my Desktop Engraver is chugging away making larger identification plaques for the instruments.
GPS
I’ve looked around at a few popular GPS’s and where to mount them for the most convenient and ergonomic use. A popular choice seems to be the Skymap III. I rejected this one because it seems too big and cumbersome and to my mind blocks too much of the view perched on top of the instrument pod. The Garmin 296 was another contender. Although smaller than the Skymap, it’s still quite heavy and awkward to mount neatly. The screen is smaller than the Skymap and would be too far away to read clearly if mounted on the instrument pod.
The new Garmin IQue 3600 seemed a better contender. Lightweight and compact with a built in antenna, it seemed to offer the level of sophistication that would match my unambitious flying plans. At this stage I really only want to see where I am and the track to where I am going. It is supplied with a cradle that can be mounted in several different ways utilising a small plate and four mounting screws on the back.
Where to mount it? I’ve seen ‘Palm’ type GPS units mounted in other builder’s machines mounted on the door pillar and on the cyclic. I bought a suction mount on a flexible stalk and tried it attached to the windscreen of my truck. It bounced around far too much for a clear view of the screen. Only when the IQue was resting on the dash was it stable enough to read clearly - not an option in the Exec. So, I fitted a seat squab into my ship and sat there with the GPS in hand looking for the best position and simplest mounting method. Here’s what I came up with.
I decided to make a mounting bracket that would clamp around the cyclic, just below the grip. I started with a 15 mm thick billet of Aluminium. I bored a hole 22,5 mm (the average diameter of the cyclic at that point) and another, offset hole 10 mm. I drilled right through the block either side of the large hole 4.3 mm (M5 tapping size)
I split the block along the centreline with my bandsaw, counterbored the two holes on one side and opened them to 5.2 mm (clearance on a M5 bolt). I tapped the two holes in the other half M5 right through.
I machined away all excess material and radiused the edges ready for polishing.
I cut a rectangle of 2 mm (1/8 in) aluminium plate and a length of 10 mm x 1.5 mm wall thickness aluminium tube. I set a dog-leg in the tube and riveted it to the plate with countersunk rivets.
Polished.
Side view. The tube is drilled and pinned to the clamp.
Here’s the view from the front.
And the Pilot’s eye view. It’s easily readable, easy to reach with the left hand and doesn’t conflict with the controls in any way.
I modified the standard Garmin 12V Cigarette Lighter plug with an in-line mini fuse holder. The cable will eventually run down inside the aluminium tube then inside the cyclic tube and connect to the supply under the cyclic gaiter.
FADEC CABLE CONNECTOR
I found a potential problem on the plug and socket joint between the Fadec Display cable and the main harness. Although the ‘D’ plug and male & female pins mate OK, the plug and socket cases are a mismatch. Rotorway’s solution is to supply a short, threaded hexagonal bush into which you are supposed to fit securing screws in both ends -from the plug and the socket case. Problem is, (at least on my ship) the screws in the plug and socket are too long and meet in the middle of the hex bush before the two halves of the ‘D’ are drawn fully together. This leaves the connector pins not pulled fully home and the plug and socket free to wiggle around.
A simple fix is to, in effect, shorten all the screws by fitting washers under the heads
A tight connection - as it should be.
I had some weird swooshing noises through the headset when the radio volume was turned up high. I tried to clarify the installation wiring with both ‘FLIGHTCOM’ ( the manufacturer of my Denali Headsets) and ‘MICROAIR’, (the manufacturer of my radio). I think they both must operate a maximum ‘E-mail -per- customer’ policy because I only managed to get a limited amount of information from them both before they stopped replying to my E-mails.
I did a little more research for myself and read somewhere that the radio wires should be separated from all other power supply wires. So I made some simple ‘stand-off’ supports from spare Pitot tubing and separated the headset cables from the others as far along the loom as I could. And it seemed to work.
Another potential problem was a sticking PTT switch. This turned out to be simply the switch rocker rubbing on the pistol grip cut-out. I shaved a few extra thousandths from the switch opening with a modeling knife - No stick.
Here’s a shot of my Cabin Ventilation controls. The switch in the middle is for my little Axial Fan and has a red LED in the end indicating ‘ON’ - it saves the bother of wiring a separate warning light.
COMPASS
I decided to change the horizontal compass supplied with the kit for a vertical card compass as fitted to my Robinson trainer. I find it much more intuitive to use - I need all the help I can get!!
I converted a Camera Suction Mount for the screen fixing. These things have a threaded knob that positively (or negatively) pulls an incredibly strong vacuum on a good surface - like the Plexi screen. I reckon this is a much better idea than bonding the compass with Silicone. You can easily calibrate it and move it if need be. The CAA’s opinion remains to be seen but I can’t see why not.
FUEL GAUGE CALIBRATION
The fuel gauge is calibrated only in 1/4, 1/2, 3/4 etc so I thought I’d get a better idea of capacity and fuel levels in the tanks. From empty, I added a gallon at a time and noted the gauge reading. I found a length of plastic curtain rod which was flexible enough to bend around the internal walls of the tank and calibrated it as I added fuel by engraving the graduations with my Dremel.
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