TYC is very proud to have our Cooling Gill repair bushing kit featured in the latest issue of Red Alert Magazine. Since it went to press we’ve upgraded the product a little. Here’s a quick look at what has changed.
The drill template still has a molded fence to ensure correct edge distance, but now three stations with drill bushings are provided, so adjacent damaged holes can now be repaired without repositioning the template.
After removing Gills, lock your template in position over the damaged areas.
Do this by pressing two of the drilled-head M4 Gill Vane Position Screws that you just removed (to release the Gill Vane) through the smaller holes in the template and into aligned holes in the ring beneath.
Using the ID of the drill bushing, you can still scribe an accurate circle around the true center of the damage - in preparation for filing by hand- but now instead, if you wish, you can simply pass a drill through the damaged area, saving a little time.
These hardened drill bushings will keep your 5/16” diameter drill bit centered and on a true perpendicular axis. Remember to remove material with the least drill pressure required because the plastic template will soften if excess heat is generated.
Additionally, you’ll see shallow holes have been molded into the inner curved face of the plastic template.
As you progress from one hole repair to the next, these recesses fit the hex heads of repair bushings already installed .
No change to the kit price and three repair bushings with nuts are still included. Once you’ve installed one, the axles feel so solid you will want to continue!
Note that, although very thin, this additional thickness of the repair bushing’s hexagon head at the base of the gill vane has to be accounted for somewhere. If you need to make repairs that are diametrically opposite, be prepared to leave out washers, or file down the short stubs of tubing that protrude from both ends of the Gill vane.
As you remove the Gills, you will almost certainly find some of the Gill Vane Position Screws that have flats worn on them.
A sample of the stainless ones Craig Payne used to make are shown at the top. Replacements for these Gill Vane Position Screws are now available from TYC but in hardened material.
When it comes to removing wear in the Gills assembly, attending to sloppy Gill bearings is a good place to start.
Keep an eye out for more TYC products to fight vibration and wear in the Gills Assembly during the coming weeks.
Radial Engine Cooling Louvers live in a world of high vibration and varying air loads.
Add resonance - and any looseness in rivets or bushings in this mechanically complex Gills assembly quickly shows up as wear.
Tension springs between the gills are there to mask this, but grab any gill without a spring attached and 1/2” of rotational play is not uncommon. If you don’t check for missing louver springs during the Daily Walk around, you may soon discover gills with irreparable damage.
One weak spot of this CJ and Yak 50 Louver design is at the lower end of the steel axle where it passes through a hole in the aluminum ring. On your plane, if you can grasp any Gill/Louver at its base and create perceptible movement, that hole in the Inner ring isn’t round anymore.
The head of the axles that run down the center of the Gills have been formed from round bar into a square T shape (to stop axle rotation) - and there’s a matching slot in fishplates riveted to the exterior cowl ring. Like spokes on a bicycle wheel, tension in these axles via two 7mm lock nuts nuts at the inner end, draws the outer ring into an even circle.
On the Yak 52, which came later, design of the gills assembly changed in these two areas.
The Yak 52 inner ring has riveted M4 anchor nuts for each of the 28 axles ( no fiddly double locknuts involved) and the top of the axle now has a 100 degree countersunk head, slotted so you can adjust tension easily with a screwdriver, (fishplates riveted to the Yak 52 outer ring have a mating countersink instead of the T slot.)
Let’s say your 50 or CJ has many Louvers that are worn in this area.
For Yak 50 owners, one solution is to buy TYC’s fit-and-forget Factory Refurbished Gills assembly, which will have the newer 52 style components.* The prop hub must be removed, but then it’s a simple task of undoing the old brace supports & re-attaching the entire new assembly.
At $2300 USD however, the convenience and reliability of a zero-timed gills assembly comes at a price that may not be for everyone.
For the more cost-constrained, hands-on CJ or Yak 50 owner looking for a robust improvement to one or two sloppy louvers, here is a solution
This repair kit includes a plastic template that will align a larger hole precisely over the original center of any damaged axle holes in the inner ring.
Use the plastic template to scribe a 5/16” circle that encloses most or all of the damage.
Carefully enlarge the damaged hole with a round file to just inside your scribed line....
...then complete the hole by passing a 5/16” diameter hand reamer through the template.
Remove the template & insert the steel bushing provided with its 7/16” hex facing out.
Tighten the MS21042-4 locknut provided onto threads protruding on the inner side. (Use a 5/16” wrench for this locknut).
This new bushing for the lower end of the gill louver has an internal M4x.7 thread to receive the axle.
The last step is to use a piloted 100 degree countersink on the slotted fishplate riveted to the outer ring.
Don’t forget to reinstall the original washers you found on both ends of the louver, then use a flat blade screwdriver to adjust roundness of the assembly.
Ensure all gill louvers have axial free play and remember to reinstall all tension springs.
The critical bearing surfaces between steel and aluminum has been been increased and now the steel axle bears on a steel bushing.
Individual Yak 52 style axles and additional repair bushings/ extra locknuts are available individually on the website.
*(The Yak 50 does not have cut louvers for blast tubes to the compressor, generator etc, so the Yak 52 Factory Replacement Gills set will need these louvers replaced with the solid style when used for a Yak 50)
In the unfortunate event of a gear up, the Yak 52’s wingtip rib often seems to take the brunt of the damage. If you and your mechanic are facing Yak 52 wingtip repair, TYC Is here to help.
These Port and Starboard Yak 52 wingtip ribs have been hand-formed from over a steel pattern, developed from a scan of a new factory part. They are supplied clear anodized with Dichromate coating for best paint adhesion.
These ribs have the recessed formed hole - but without the four nut plates. Our field research revealed that both the orientation and bolt circle diameter of these nut plates vary from one Yak to the next, so we have left them for you to create! One purpose for that large hole with a rolled edge in the center of the rib is to accept a stout bar to take the weight of the outer portion of the wing during separation from the fuselage. You will notice other aligned holes in adjacent inboard ribs.
After the emotions of the moment have subsided, actual gear-up airframe damage is rarely as bad as it looks.
Kudos to those prepared keep another of our Yaks in the air after the unimaginable happens
When structural engineers talk about “efficient” structures, this may be their way of saying they didn’t leave much unstressed metal in the design.
Case in point: Have you been hearing heavy clunking sounds from the upper ends of your Yak 50 gear lately, during ground handling?
The kind of comforting ‘Clunk’ you’d always want to hear two of in the circuit, doesn’t sound right at all when you’re simply manhandling the plane by its tail on the ground.
TYC has replacement Main Gear Axles and Bronze Bushings.
Get the plane safely on jacks, remove one gear fairing and have somebody carefully apply side force to the wheel while you look for relative movement at the pivot joint.
You might see this....
A well-designed pivot joint distributes loads to the participants, (axle, bushings and housings) so they all grow old gracefully together. When failure finally occurs, the designer knew how to make it non-catastrophic - and like a painful knee, noise is there to alert us something is worn or abnormal.
The steel top of the Yak 50 strut ( the ‘trunnion’) has two outrigger towers through which the head and tail of the bolt pass. The outside of the trunnion head has a flat milled in it to prevent the axle’s hexagon head from turning - Shown in white at lower right in the picture below.
In the outriggers, steel bears on steel. By contrast, the inner supports (attached to the wing) are made of Aluminum with press-fit bronze bushings. These bushings take the landing loads into the wing structure. Here the Steel axle runs on Bronze and because of relative movement during gear retraction & extension, grease is delivered through a drilled passage down the axle from a Zerk fitting in its hex head.
The axle is loaded in shear - so its castellated nut with cotter pin just keeps things lined up - no need for it to be so tight that it’s creating axial tension.
-The first surface to go might be the bearing surface of the steel bolt itself. Or the outer diameter of the bronze bushings that have worn the wing housings slightly oval - or the steel bores going out of round in the trunnion outriggers. A replacement axle/ bushing set
needs to be sized to accommodate any of these wear/failure combinations.
Your mechanic will know how they want to go about fixing it, probably involving an adjustable reamer carefully piloted between the both sides of the joint to ensure axial alignment.
The dimensions of this repair axle and bushings set are all over-sized so that material from any interfacing surface can be judiciously removed. This is challenging work, best undertaken by those with prior experience. In the case of the Yak 50 trunnion, (being quite rare these days), needing to ‘put metal back’ (after too much was removed during the repair), would be very undesirable. Do a skills self-assessment before attempting this, and ask for help upfront if you know you’ll need it.
The only good clunks are airborne clunks, and only when commanded by the gear lever.
Please ( have your mechanic) call us if special dimensions are required.
What could be easier than installing a Skybeacon on your Square Wingtip 52 ?
So we made it harder. You have to drill a hole now !
But then physical installation ( that uAvionix don't talk about) is done!
More info here
It would have been interesting to have been a fly on the wall in the 1980’s when design requirements for the Yak 55 were being drawn up at “the Bureau”
Its lines are so different from the sleek, curvy single-seat fighter appearance of its predecessor, the Yak 50.
But as the seventies turned into the eighties, the Yak 50’s were being found too sleek, too slippery for the slower style of world championship aerobatics that was emerging. It would slice its way through the aerobatic box too fast, denying advantage to Russian team pilots.
No, it was clear. A lighter airframe with more drag was needed. Nothing short of National prestige was at stake.
And so it was that one cold Friday night in January the three members of the Yakovlev 55 core design team made their way to Gorky Park, with pencil and paper, a bottle of Green Label Vodka and a Tab of acid - and the rest...is history.
The ugliest plane imaginable.
At least that’s what I thought too, until one spring morning several years ago when Vladimir let me degrease the belly of a customer’s 55/M.
You couldn’t have made this up.
Almost as though the 55 was infecting me with its subtle pheromones, by the time it was beginning to sparkle, I was already besotted with its ridiculously fat Vertical stabilizer, the bulbous shoulder wing, spindly model airplane gear and cool raked-back bubble canopy.
Just can’t explain it.
There are certain viewing angles from which the 55 can appear less than beautiful. Like saggy gear. You don’t want saggy gear - and your propeller tips certainly don’t want to be that close to the ground either. (Thank heaven for TYC’s gear extensions! )
But soon afterward I had the opportunity to join those few, those happy band of brothers who have taken a 55 aloft.
And that changes everything.
What an underrated, undiscovered plane this is!
Back at Gorky Park, they had been able to scrawl a few things down on the vodka-soaked notepad, before starting to notice their breath was now making technicolor ripples in the night air. One item on the ‘clean sheet of paper’, was to ditch the weight associated with retractable gear.
With fixed metal gear, you could toss the emergency system, get by with just one tiny air tank for engine start, even ground-fill it!. (“We won’t even hook that compressor up”).
It was to be the end of the line for air brakes too.
Hydraulic puck brakes!...Once more three re-filled shot glasses crashed together.
Head held high, tovarich Kondratiev announced with certainty that the electro-pneumatic start valve had outlived its usefulness. Always requiring perfect tank pressure and a fully charged battery - Bah! - so ‘Western’. “A push-button air start” he declared to the frosty stars.
About the same time, tovarich Drach had become aware of spiraling iridescent carousel horses, corkscrewing up into the shimmering night sky above their beloved Capitol, above the amusement park, above the three huddled designers, none of whom were now feeling any pain.
“Even your thumb cannot push against 50 bar of air pressure, Comrade” noted Sergei Yakovlev dryly.
There was a long pause. The beautiful Moskva river before them pulsated black and silver.
“We will have a lever” said Kondratiev with finality.
Today, you can’t actually see this lever, or the valve, since they got hidden behind the panel. The push button is by the Magneto switch where you’d expect it though, under its black metal guard.
50 and 52 owners anticipate a characteristically prompt motor start when the button is pressed in their planes.
In the 55, it’s different.
Here the mechanical push button slops around like some handmade key in a medieval lock, requiring half an inch of travel before you get any reaction.
That, unfortunately, is how it is with levers.
But let’s give the guys their due, they certainly condensed the air start operation down to one valve.
Full Air tank pressure bears down on the backside of a piston whose other side houses a rubber seal hard against a raised lip in the valve body, preventing air leakage.
The aforementioned starting lever ( via the push button) rocks against a convex nut on the end of a shaft, moving a shuttle forward against the metal center of the sealing piston, pushing it off that lip.
Full pressure air from the tank rushes forward and up the sidearm of the start valve, out to the air start spider, onward to join a well-timed shower of sparks above primed pistons.
But 50 bar of air pressure wants out of our little start valve in every direction.
They had to design in a rubber shaft seal on the downstream side of this air start valve to reduce lost air during the start. ( item 10 in the diagram)
Then, once the engine was running and the Pilot had released the push button, re-seating the piston, the downstream side of this air start valve was still pressurized. The push shaft ( item 9) had to be drilled to vent the post-start pressure to atmosphere.
High level simplicity had bred lower level complexity.
Maybe because this start valve is hidden behind the panel and not in your face, it’s easy to forget that the rubber face of this Main sealing Piston ( item 8) sees tank pressure 24/7 ( or for as long as there IS tank pressure) - because the guys decided to go without a main air valve too.
Yep, there isn’t one on a 55.
And just like PRV pistons, eventually the sealing rubber takes a set.
And starts to leak.
With only 3 liters of air on board, some 55 pilots get range anxiety for good reason.
Heard any air hissing from behind the left side of the panel on your 55 recently?
TYC is now overhauling these valves, pressure testing them for the absence of leaks before yours is returned to you.
Items 3,8 ( including its rubber insert, a rather tired one is shown above), 10,12,13 and 14 in the factory diagram above are replaced with new parts, sourced or made in the US.
(Item 13, the set screw is replaced with a Socket Head style and a suitable Allen key is included.)
This won’t fix the entire push button/lever linkage sloppiness, but it will return sobriety to your Air gauge while dialing down the pilot’s range anxiety.
The Yak 55 - possibly the last in a grand tradition of Yakovlev competition monoplanes - and almost certainly designed using a Slide Rule.
Before the “big nineties”, before the sun rose on the Sukhoi Designers with their computer graphics, exotic blends of titanium for this, carbon fiber for that, their constantly irritated red eyes and permanently itchy noses.
Love your 55 - it's an exotic masterpiece which asks only that it be viewed correctly-through the hangar doors of perception.
Nobody likes to be taken for granted.
Especially not the fuel & oil hoses in your engine compartment. You’d definitely want to change them before they decided to fail during a cross-country.
Although they are ‘on condition’ at your annual inspection, it would be good to have a rule of thumb for hose life - because they are mission critical, so - how many years should you expect to get out of your Yak 52’s hoses?
Here’s a document pertaining to DOSAAF operations ( lots of short student flights, multiple landings & power changes) that the total life of Yak 52 hoses, including storage is 9 Years
The design bureau used three or four-digit hose numbers as shown below, to describe Yak hoses:
We've prepared pictures and descriptions to help you identify the hoses you need.
Certain airframe-specific hoses would be prefixed by “52” then follow a different designation if the hose had a banjo end fitting, for example.
And if you've got a hose in one hand but the other hand is scratching your head, take a minute to check this out.
Anyway, whenever it’s new hose time, TYC is ready for you. On December 1st 2019 a customer used the website to order 7 Fuel and Oil hoses, which were shipped out to him on December 3rd.
Fast enough for you ?
No parking on the dance floor, Baby.
New Russian hose material will be assembled with used, but serviceable, Metric Hose end fittings including Firesleeve where appropriate. When your shipment arrives, remove your old hose and fit the new one.
Too easy !
But it doesn’t stop there.
Cut the hose fittings off your old hose ( about 4" from the ends please - to give us something to grab on as we disassemble it), ship them back to us, and if they meet our ‘accept’ criteria ( see below) we’ll electronically refund you up to $15 per hose fitting upon receipt & inspection.
No need to send us modified, welded, chewed up or damaged fittings that you wouldn’t want on your plane. The two criteria we care about are:
We really need your core fittings - and we need them in good shape because your formation Wingman might be our next hose customer.
As usual, your satisfaction is guaranteed.
Please note that only stock Yakovlev hose sizes are on sale here. If you have inserted a fuel totalizer, an aftermarket Oil Filter in an existing line or switched to Aeroquip, the part numbers shown on the website are not guaranteed to fit - but we can still reproduce what you need, so email email@example.com or call 619 933-2571 and talk to us.
An informal TYC survey suggests that as few as 1 in 8 Yaks still use Russian plugs and the factory ignition harness.
At some point it's a foregone conclusion that the insulation on one or more of those eighteen tightly bundled plug leads will break down, inside that curved metal Factory shroud, and start sharing its life story with a neighboring wire. There may be radio noise, engine misfiring at high power settings or other mayhem.
But when the time does come to switch to Auto plugs, be sure of this:
First, nobody makes the switch until they have to. Russian plugs work great even though they are more costly than the NGK’s you will fit next.
Second, nobody fixes failing Russian Ignition harnesses. Not even DOSAAF mechanics did. Too time consuming and ambiguous to troubleshoot- they would toss it & fit a new harness.
Today, thanks to Modern Auto plug wire technology, you have another option.
Third, once you get to actually installing these Automotive Ignition leads on your Yak, you’ll experience a whole new level of frustration while trying to make a sound connection between the Distributor cap and the new conductor core.
The Russian plug wire is the most basic stranded conductor imaginable. Once the pointed metal screw in the red mica Magneto distributor cap pierces the black rubber insulation, a metal to metal contact is assured. Screw that baby home & go flying.
By contrast, Auto plug wire yields to external penetration in a more nuanced way.
After one half-turn of the pointed screw, your continuity meter will be beeping, (usually indicating 4 to 7 ohms between its ends depending on the plug wire length) ...but turn the screw in another half turn and continuity is suddenly lost!
Here's why. The core resembles a hollow Nylon guitar string. Around this flexible base a ceramic spiral conductor is laid. Someone determined the physics of this spiral transfers High Tension better than the Russian stranded stuff. It's efficient, but fragile - easy to break with a pointed screw. (Outside the spiral will be a thick layer of fibrous insulation then the colored plastic outer sheath, perhaps with an extra layer of RF shielding braid.)
One recipe for installation success is to strip the outer layers for quarter of an inch - being careful not to cut the guitar string or the spiral conductor. Once this delicate ceramic layer is visible, take the barrel of a crimp style automotive connector- trimmed to match the stripped length - and, using suitable pliers, close it firmly around the carbon spiral. Now the tip of the pointed screw will sink into the soft aluminum of the crimp, making a more reliable contact.
Simply ( As they say in the instruction manuals) repeat 17 more times, checking continuity & noting end-to-end resistance as you go.
Since you’ll have purchased Auto plug wires with molded-on plug caps, remember to thread ignition leads through their respective holes in the Magneto cover plate before terminating them at the Distributor cap.
The cap for the left mag has 10 holes (because of the Shower of sparks lead), the one with 9 holes is destined for the right Magneto.
4 fixing Screws per Magneto cover, drilled for safety wire, are included in the kit.
These covers are drilled for 8mm diameter Auto Ignition Leads but can be enlarged to suit larger diameter plug wires. Note the middle lower pair of Ignition Lead holes are splayed outward on purpose to guide those two conductors towards their corresponding receptors on the distributor cap.
As the fog rolled in you dimmed the cockpit lights
Those San Francisco nights
You were the best in town
Joining Victor 107 sealed your fate
Checked in at Golden Gate
Then you got too close to the ground.
Did you feel like Jesus?
Did you realize
You were just a Target in their eyes
Oakland Center started pushing tin for real
You shoulda seen the zeal
Everyone stopped to stare at your ADS-B suicide
Northern Tracon had your number on the wall
You must have had it all
You'd head for Hayward on a dare
then you'd just go around
Could you live forever?
Could you see the day
Could you feel your Licence crumple up and fade away
Walk it off, walk it off Kid Charlemagne
Walk it off Kid Charlemagne
Your insurers have all left you in the red
You spend the days in bed
Life can be very strange
Flight School Cessnas that would never paint a trace
They've joined the human race
On the Magenta Line
Son you were mistaken
They just want your pelt
Look at all the white men here to help
Walk it off, walk it off Kid Charlemagne
Walk it off Kid Charlemagne
Fix this squitter else we'll all end up in jail
The third time that it’s failed
since I turned on the strobe
Is there gas in the Champ?
Yes, there's gas in the Champ
I’m staying outta Mode C veil
from now on
Careful what you transmit
'Cause the man is wise
and he’s got extinction in his eyes
Walk it off, walk it off Kid Charlemagne
Walk it off Kid Charlemagne
Five weeks left
And instead of doing something about it, i’m writing embittered parodies on why I have to spend a quarter, maybe a third of my year’s flying fuel money on bullshit Avionics that’s going to strip me of my privacy in return for some Little Bo Peep weather product.
Going to be a initial flood of airspace violations in early 2020? You know it - but that’s not the real taste it leaves in your mouth.
Here’s a clue. If all the gallons of 100LL made in a year were compared to all the gallons of Jet A, the refineries could make all the 100LL in one day out of the 365. And ask your FBO what a money spinner 100LL is for them.
The point ?- if the FAA woke up tomorrow & discovered GA had died in the night, you get the feeling there wouldn’t be too much handwringing about it.
Ten thousand Asian students in Cherokees bouncing off each other in the pattern won’t change that.
Nor will AOPA opening its doors to Drone pilots so the pink button-down shirts at Frederick can still afford to keep Buffy at Annandale.
Start here, then marginalize us further with skyrocketing insurance premiums.
(Oh - and ADS-B out needs to be on while you’re taxiing too.)
Boomers like me though can get the bus driver’s attention and just get off at THIS stop right here - having had the best ride ever, whether that’s the environment, the art of conversation, GA or affordable Healthcare.
Happy Thanksgiving Everyone!
Not sure where this bus goes next but enjoy the ride!
Rant over. ( in the background: gets checkbook out)
John flies out of KSEE whenever he can scrape together a few bucks to fill the tanks