Landing Light Parts Prepared For Primer

It came as quite a shock last night to hear the weather report calling for near 60 degree temperatures today and tomorrow. Because of winter low temperatures, I was planning to prime the landing light’s aluminum parts with rattle can chromated primer as needed. However, decided since tomorrow is also forecasted to be around 60 degrees, it would be best not to complete the wiring and to begin preparing all the aluminum parts for the landing light assemblies for Akzo primer. The mounting ribs can easily be seen through the light’s lens so it would look much nicer if the same primer can be seen for all the wing’s components.

The two ribs that mount each landing light come as one piece, so the band saw was used to separate the left and right ribs for both lights. That was followed by filing all the ribs smooth then drilling out the holes for the wire run grommets. Here again the size of the hole was upped to 7/16 on the drill press using a step drill so the larger SB-437-5 grommets could be used.

                                   Using the band saw to separate the landing light’s left and right ribs.
 

                            Top is how the ribs are shipped from Van’s … bottom is left and right separated pieces.

Blue tape was placed on the step drill so the proper hole size could easily be seen as each grommet hole on the landing light ribs were enlarged to 7/16” for the larger SB-437-5 grommets.

                                    Using a step drill in the drill press to enlarge the hole for the wiring grommet.

Next the rib doubler plates were deburred and the mounting slot checked to make sure no binding occurred when an AN-3 bolt was inserted in the slot. The doubler plates also required machine countersinking for all the rivet holes that will mount them onto the landing light ribs.

                                               Using the drill press and countersink cage to machine countersink
                                               the landing light rib’s doubler plates for AN426AD3 flush rivets.

There are two lens backing strips per each lens. All four required some filing to smooth rough edges. Extra care was taken to make sure these were very smooth where they will be touching the plastic lens. The backing strips also require dimpling at the rivet holes that will secure the nutplates that will ultimately hold each landing light’s lens in place.

              All of the landing light’s mounting hardware for both lights fully prepared and ready for primer tomorrow.

Left Wing Light Cutout Debacle Avoided

Wow! This was a close one … while on the VAF RV-12 forum yesterday, I spotted a fresh post stating a fellow builder discovered his lighting kit template on page 40-17 did not match the holes in his parts. Unfortunately, the builder discovered this AFTER cutting out the leading edge of the wing and drilling the lens holes per the template for the lens backing plate holes and light bracket ribs.

I immediately trotted out to the “still cold” DOG Aviation production facility to compare my landing light parts to the original template shipped with the wing kit and the extra template I ordered along with the parts for the left wing's landing light. This is very timely because I’m not far from cutting the holes for the left wing’s lights.

While checking the original lighting kit parts and the newly received parts to the original template, sadly, I had the same issue as the other builder … all the holes on the template for my backing strips were WAY OFF.

Next, the new template received with the second light kit recently delivered was checked with both the old and new parts and that template was OK … not spot on, but close enough not to create any issues. Both drawings are the same date 7/12/11 and Rev 1. Apparently, the bad template was not scaled correctly when it was printed. I’m guessing for some reason the printer used to reproduce the template page must have scaled the drawing to fit page, creating a batch of missed sized drawing templates.

Below is a photo of a lens backing plate placed on top of the drill hole template … the scaling error is easily seen.

A lens backing bracket on top of the drawing. The screw hole on the left is in perfect alignment, the second from the left is almost half off center, the third hole is almost off by one hole width and the far right hole is about a hole width and a half off. … not good.

Fortunately, I have one good template sheet and a replacement on the way. The call to Van’s this morning will bring about a change in their instructions to remind the builder to verify the scale of the template pages. In Van’s defense, at the very beginning of the plans in Section 3 (Tools and Workspace), Page 4 has a reference for the template page size used throughout the plans calling for a size of 16” x 10 5/16” measured at the margins.  Incidentally, my “bad” page measured around 15 1/2” x 10 1/4".

 

Return from the Future: Section 3-4 of the plans tells the builder to verify that templates in the plans measure 16” x 10 5/16” at the borders.  I have had several calls to Van’s regarding that scale and the fact that the replacement templates didn’t measure up correctly nor did the PDF file Van’s sent of the template (which was printed out at a blueprint shop) or even the subsequent replacement templates received from Van’s. The mailed replacements and the output from the PDF file were all 16” x 10 9/16”.

I had a long discussion with Joe at Van’s about the mismatch just prior to Sun and Fun … so waited until yesterday (4-23-2013) to make the follow up call. Joe told me after checking with the drafting department, it was concluded the scale given in section 3-4 was incorrect. The template pages should measure 16” x 10 9/16” … NOT the 16” x 10 5/16” as stated in section 3-4.  Joe told me Van’s has a correction in the works for that typo error in section 3-4. So RV-12 builders take note of that correction and check your templates accordingly.

Left Wing Wiring and AOA Tubing In Place

Taking advantage of the slight bump in temperatures into the low 20’s, decided to pull the remaining wires and Tygon tubing through the previously installed nose rib grommets. It did not take long before noticing a small issue. The inboard eight ribs had SB-437-5 grommets which worked wonderfully … however the remaining outboard ribs had SB-437-4 grommets which created a “snug” fit for the two shielded wires to be connected to the nav/strobe lighting and left landing light. Once the wires were installed, the fit was snug enough the ribs could not move easily. I felt this could possibly create an issue when trying to align the ribs to the skins so replaced the SB-437-4 grommets with 437-5 grommets. Now all the ribs can be moved easily.

                                                                   Pulling in the nav/strobe shielded cable.

After all the wires were happily in place, the Tygon tubing that will be used for the Angle Of Attack indicator plumbing was installed.

                                             Pulling in the Tygon tubing that will be used for the AOA sensor.

                                              Left wing wiring and AOA tubing in place … finally!

Now that the left wing wiring and Tygon tubing is finally in place, next up … stripping the wiring and crimping connectors onto the ends of the wires … that is until my fingers get numb from the cold.

Left Wing Wiring Begins

Drilling out the grommet holes on the inner most ribs of the left wing turned out to be much easier than first thought. The step drill was hitting the previously installed stand off on the inboard rib and for that matter, so would the chuck of the drill.

                                               Step drill hitting previously installed stand off on the inner most rib.

I was prepared to a little “creative access” by way of slipping some vinyl tubing over the shank of a drill bit along with a dowel rod inside the tubing to keep rigidity and try using that to extend into the next rib bay to get to the inner ribs.  Fortunately, none of that was necessary because my 7/16” drill bit was way longer than I remembered and it was able to reach with no issues.

                                             At the root of the wing where the ribs are doubled up, inner ribs were
                                             drilled by going through the grommet hole in adjacent ribs.

My suggestion to builders interested in using shielded cable for the strobes and the Tygon tubing for the angle of attack indicator would be to drill all the W-1208 nose ribs to 7/16” for Heyco SB-437-4 or -5 grommets before riveting them in place. It is easy enough to do after the ribs are attached onto the wing spar, but you just have to jump through some extra hoops. If you are adding a left landing light and also using sheilded cable read the next paragraph.

Return from the future … the plan was to use SB-437-5 grommets in just those locations where the Tygon AOA tubing runs adjacent to the wiring and SB-437-4 grommets where the two shielded cables run by themselves. Because I’m using shielded cable for nav/strobe lights & the additional left landing light, the fit in the SB-437-4 grommets is snug enough so when both sheilded wires are in place, the ribs don’t want to move easily. This may make aligning the ribs to the skin more of a challenge than it should be, so I’ve changed those grommets out for SB-437-5 grommets. Now the wires do not prevent the ribs from moving easily. All of the rib grommets are now SB-437-5 except for the very last outboard grommet which is a SB-437-4.

After all the grommets were inserted into the ribs, the first wire installed was the stall warning indicator wire and by then my hands were getting quite cold so called it a day.

                              Stall warning indicator wire - first of the wing wiring to go into the left wing wire grommets.

Left Wing Landing Light Parts Arrive

Taking advantage of a one day heat wave, got into the shop and drilled out all the rib grommet holes to 7/16” using a step drill and a 7/16” drill bit for the inboard ribs where the spacing prevents drill access (even with the 90 degree drill). While at it, also drilled out all the rib grommet holes for the right wing as well. The innermost three ribs on the left wing will require “creative access” more on that in a later post.

                                                         Drilling the grommet hole in one of the W-1208 nose ribs.

The additional landing light for the left wing, which will allow wig wag operation, arrived yesterday. In addition to the landing light there is a lens, mounting ribs, doubler plates, backing strips for the lens and a few pins for the electrical connector. Also decided it prudent to order the one page of the plans that has the hole cut out and rivet template.

For those interested in installing a landing light in the left wing, here is a list the major parts you will need minus the screw hardware.
1  LL-200 landing light (molex power connectors/pins included)
1  W-00014 landing light lens
1  W-1223B landing light ribs (cuts in half to make a left and right rib)
2  W-1223C rib doublers
2  W-1223E lens backing plate
8  K1000-06 nut plate
1  RV-12 Page 40-17 plans template page (optional)
8  ES-00079 Floating connector pin (pins for the electrical connector at the root of the wing .. not sure if necessary, but wanted a few on hand)

                                                        Parts to install the additional landing light for the left wing.

The left wing’s electrical connector will accommodate the light addition, but will be maxed out. The ground, stall warning, and nav/strobe wiring consumes 5 of the 8 contacts leaving three available…and that is what is need for the landing light power, wig wag power, and the master to slave (think wig wag sync) wire.

For wig wag operation all that needs to be done is wire from the right light’s master out (green wire) to the left light’s slave input (blue wire) and have power applied to both light's wig wag power (yellow wires). Note: For wig wag operation, power is NOT needed on the steady on (red) wire and if power is applied to the wig wag (yellow) wires it overrides the steady on power (if present) and places the light in a pulse or wig wag mode depending on a one or two light instillation .

Wire Labeling SNAFU

Yesterday, in an effort to put off working in the cold shop for one more day, decided to spend a little time with the electrical schematic and draw in the wiring for the landing light to be installed in the left wing along with adding a couple of tables identifying the wires for the AeroLESs landing and nav/strobe lights. It will be time well spent.

While perusing the schematic, decided to break out the label printer and make a bunch of heat shrink wire labels in advance. Of course, some wires have the same wire run number, but appear in multiple places. One such example: The strobe sync wire is the same wire number in both wings and the fuselage. Being lazy, I thought since I’ve already typed the wire name into the label maker, may as well print out heat shrink labels for all the termination points while the wire run name is in the label maker. Saves time retyping all the names later … great idea in theory!  However, I ran out of heat shrink tubing before getting all the wire runs needed for the left wing printed out … and I did not have a spare cartridge because I was not sure how well the Dymo label maker would work on heat shrink tubing, so only purchased one cartridge the first place.    BRILLANT, ... JUST BRILLANT!!!!

To my defense, I knew the standard label cartridge contained around 18 feet of vinyl labeling material. So it never occurred to me that the heat shrink cartridge has ONLY 5 feet of heat shrink tubing in it! Oh well, more is on order and should arrive Tuesday. In the mean time I can still run the wires through the wing rib wire grommets.

Speaking of wire grommets, test fitted the wiring with the larger 437-5 grommets that will be used on the innermost ribs passing the Tygon tubing. Happy to report there is plenty of room for both the shielded cables running to the landing light and nav/strobe light, along with the Tygon AOA tube plus the wire for the stall-warning indicator. There is no hint of binding or excessive friction and plenty of room for additional non-shielded wires. Once the temperatures get UP to 33 degrees (today’s predicted high), plan on trying to make a little progress in the shop by enlarging the rib grommet holes to 7/16” for those ribs which will have the Tygon tubing passing through them and snapping the 437-5 grommets in place and running some wire through the grommets.

Lighting, Pulse Is OK - But Wig Wag Is Better!

Having an electronics background, it was bugging me not having a schematic drawing to use as reference once the electrical connector wiring  begins … especially since there will be some small changes to the electrical system. It is nice to see the "big picture" sometimes.  Van’s has a schematic drawing online for the builder to download which is drawn in such a fashion, in order to read any of the labeling, it requires zooming so far you lose all prospective. Trying to trace a wire is … well “fun”. Not!

Decided to have the entire schematic drawing printed out on 4 x 3 foot paper and it was still tough to read the labeling, so had the drawing divided into four quadrants and each of those printed onto 4 x 3 foot sheets. Honestly, the schematic would need to be about the size of the side of a cargo van as to be easily read.

                The whole schematic is now on one 4x3 foot sheet … still difficult to read the labeling but it is legible.

The lower quadrant of the above schematic printed on a 4x3 foot sheet … at least now it’s easier to read the labeling.

Lighting - pulse is OK, but wig wag is better!
Although not much is being accomplished in the shop, behind the scenes there has been a flurry of activity. The decision was made to order a second landing light so wig wag lighting would be possible. One thing is clear to me, a plane flying in the pattern with wig wag wing lighting simply commands attention!

Those familiar with the RV-12 lighting kit know, as shipped from Van’s, the lighting kit only has one landing light which is installed in the right wing. Basically, the reason for this is not to over tax the somewhat anemic electrical system of the Rotax engine. The landing light, which is manufactured by AeroLEDs, has the provisions for both steady light and a pulse mode which Van's incorporates. The current draw is 2.6 amps when the landing light is on. In a two light instillation, the pulse mode can become a wig wag mode. For wig wag operation, one light becomes a master and a wire is run from that light's master output to the slave input on the second light which enables wig wag operation. That got me thinking, if one were to add a second light on the left wing but only use the wig wag mode, the total current should still be 2.6 amps … because only one light is illuminated at a time.   A call to AeroLEDs technical support confirmed my suspicions, so an additional light and mounting hardware was ordered from Van’s Aircraft on Monday.

I still plan on running a power lead to the left landing light’s steady on, but will not connect it to the switch on the panel. But it will be there should there be an improvement in the electrical system in the future which allows for more power. To be honest, I’m not planning on flying at night anyway, so doubt the landing light will ever be used as such. But using the wig wag mode of those bright lights … you bet! See and be seen!.

The decision to add an additional light on the left wing created yet another grommet issue … the 437-4 grommets I just ordered proved to be a little tight with the addition of the second shielded cable for the landing light along with the Tygon tubing, so an order was placed through Mouser for 437-5 grommets. These grommets use the same size .437” mounting hole as the 437-4 grommet but have a wire hole of .312” as opposed to .270”. The new grommets just got here today so will see how well they work out tomorrow … suspect there will be plenty of room now and the good news is the new grommets still only require the hole in the ribs being enlarged to the next size up on the step drill from the original hole size.

Labeling Wing Wiring

Not wanting to waste a 60 degree winter day, a little forward progress was made in the shop. The first chore was attaching the mounting standoffs for the electrical connections onto the inboard rib. After playing with electrical, decided it would be a good idea to primer all of the machine countersinks in the spar … so did so with the PTI zinc chromate primer.

While attaching the standoffs onto the left wing, it quickly became evident my stubby Philips head screwdriver was too long for getting onto the mounting screws (plus it required a smaller Philips tip than I had). This required holding the head of the screw with long nose pliers while tightening the standoff. I looked at the rib and realized this would have been easily avoided had the standoffs been attached prior to riveting the rib in place, so I immediately attached the standoffs onto the inboard rib for the right wing.

Builder Tip: I would suggest screwing the standoffs for the electrical connectors onto the left and right wing’s inboard ribs prior to riveting the ribs in place it will make life easier.


The larger snap bushings on order should be here Tuesday or Wednesday at the latest, so even though wires can’t be run through the ribs yet, did make a couple of ground wires and prepped some of ends for the left wing wiring.

One of the play toys procured early on was a Dymo Rhino label machine, which has been used quite a bit making labels to identify small parts in storage containers. One of the reasons it was purchased was because it can also label heat-shrink tubing. Today the first labels were made and have to say, it works great.

The first printed 1/4 inch heat-shrink tubing on a wire to illustrate the size prior to shrinking is sitting on the bottom of the label maker. I was testing the size of the smallest print … very readable.

Mounting Stall Warning Assembly With Socket Head Screws

The socket head screws ordered for securing the stall warning assembly came, so decided to get into the shop for a few minutes and make the change. The size of the Allen head socket in the new screw is 9/64” … the Allen wrench I used is rather long which may be problematic when the wing is assembled. Fortunately, I have an Allen set which attaches to a small ratchet wrench down at the Southern Outpost in case further tweaking is deemed necessary during flight testing.

                                 Stall warning assembly after changing the Philips mounting screws to socket head screws … 
                                 9/64” wrench in lower screw shows accessibility, it clears the keeper plate (barely).


Feel I will come to appreciate this small modification the first time I find myself lying on my back, under the wing, trying to adjust the stall warning assembly so the stall warning alarm sounds at the correct airspeed.

Snap Bushing Mania

Now that the shielded wire for the navigation/strobe wiring has arrived, wanted to see how well the snap bushings accommodated the shielded wire and the Tygon tubing for the AOA plumbing. The verdict … just fine if you never plan on replacing either the tubing or the wire.  There is just barely enough room in the snap bushings provided by Vans to accommodate everything without crushing or deforming the tubing. That said, because the tubing has a relatively “soft” outer surface it doesn’t slide across the insulation of the shielded wire easily once it is in place. I’m afraid should the tubing ever need to be replaced or another wire run, the friction would be so great, it would be very difficult.

                                   Shielded cable and Tygon tubing inside the SB 375-4 snap bushing from Heyco
                                   included in the kit. Everything fits … but it is very snug as can be seen here.


Decided to up the size of the snap bushing to a Heyco SB 437-4 which has an internal hole diameter only .020 larger. Now 20 thousands doesn’t sound like much, but it makes all the difference because now there is just enough extra room to allow the Tygon tubing to slide across the shielded wire with far less friction.

                                             Shielded cable and Tygon tubing inside a Heyco SB 437-4 snap bushing. 
                                             The small amount of extra room contributes to very little binding.


Fortunately, there is no need to change all the snap bushings only the inboard eight bushings on the left wing where there is Tygon tubing and the shielded navigation /strobe wiring running together. Unfortunately, the holes for the bushings will require being enlarged to the next size larger using the step drill bit.

Modifying Stall Warning Assembly Mounting Screws

While following the adjustment procedure Van’s has in their instructions for initial setup of the stall warning micro-switch& vane, I discovered the potential for a nightmare later down the road. The stall warning assembly uses two #8 8-32 Philips head screws to secure the assembly to the two nutplates riveted onto the W-1208-R nose rib. (For those not familiar with nut plates, in a nut shell they are a threaded plate that is riveted to a structure which you don’t have access to the backside of to allow for a wrench and nut, as would be the norm.

The threads on the nut plate are purposely squished a little so a screw can’t back out on its own. However, this requires extra effort when screwing a screw into a nut plate, not to mention requiring extra pressure on the screwdriver to prevent the Philips screw head from stripping.

Even with the W-1202-L skin flexed up to allow for fair access, it was not easy to screw in the two Philips mounting screws securing the stall warning assembly. (OK, admittedly it was quite cold in the shop and my hands are used to 70 degree California winter temperatures, so a small task like this seems like a much larger chore). Frankly, once the wing is fully assembled, I can’t fathom the difficulty involved to make adjustments to the assembly through a tiny inspection hole. The odds of the switch being set perfectly at this point is rather slim, so adjustments are very likely … plus to add to the difficulty, it appears as though it will also require using the left hand if the wing is on the RV-12. Should one of the Philips screws become stripped, and that would be soooo easy, it would be a colossal bummer!

The dollar bill is placed adjacent to the inspection portal to illustrate what “fun” it will be later to make adjustments to the stall warning assembly which is nestled just aft of the leading edge of the wing where there is little room.


In an effort to alleviate the possibility for a screw head becoming stripped and to make adjustments easier, I’ve decided to use socket head cap screws (Allen head) to secure the stall warning assembly, as opposed to using the #8 Philips screws. I feel it will be much easier in such a cramped location with limited visibility to just insert an Allen wrench into the screw head and have a positive fit, substantially reducing the potential for head stripping all together. The socket head cap screws are now on order. Fortunately, the shielded wire I was waiting for was delivered this evening so forward progress on the left wing’s wiring can resume.