Vibration and wear.. what a pain.
Yak drivers may be surprised to know that Nanchangs don’t even HAVE springs on the back of the cooling vanes.
So no Chang owner will be surprised to see this.
The pin that drives the control bracket has just been hammering away at the slot like a little woodpecker.
It too will probably be flattened halfway through, ( the reason people fit our hardened ones)
You can take a reasonable guess at the vane position, too…looks like a cruise setting.
If you do an internet search on “Paddy’s Wigwam”, your browser will return a beautiful shot like the one below of Liverpool’s Metropolitan Roman Catholic Cathedral in all its post-modern architectural glory.
That ‘crown of thorns’ - the ring of roof-mounted pinnacles, which was such an easy target for the unkind wigwam analogy, had something in common with our Gill vanes - Vortex shedding.
Stephen Bailey, writing in The Spectator magazine a few years ago, noted that Liverpool has traditionally not been kind to its architects.
“Liverpool was, of course, deplorably damaged by Hitler’s Terrorflieger, on account, it has been speculated, of an unhappy period the young Adolf spent lodging at 102 Upper Stanhope Street in Toxteth where his half-brother Alois lived with his Irish wife, Bridget.
The immediate architectural impulse after 1945 was to make good Hitler’s systematic and vengeful destruction.”
Within a very short time of its opening in May 1967 though, this Cathedral began to exhibit architectural flaws which led authorities to sue its Architect (Frederick Gibberd) for 1.3 million pounds on five counts, the two most serious being leaks in the aluminum roof and subsequent damage to the mosaic floors below.
You can’t see it in the photo above, but overlooking the ‘wigwam’, on the other side of Brownlow Road is Liverpool University’s Mechanical Engineering department.
Fluid Dynamics lecturers lost no time pointing out to their students how the incessant vibration of the Cathedral's conical 'thorns’ - due to Vortex shedding - was the root cause of the roof’s problems.
And indeed that it had been a Mechanical Engineer, no less, who had conceived the remedy - spiral appendages ascending the thorns’ conical surface, which now made that bitterly cold wind from the Irish Sea shed vortices in every direction, not just side-to side, thus halting further roof damage.
Those little extension springs on the back of the Gill shutter assembly aren’t the best idea, but they are better than nothing.
Nothing ( as in torn spring brackets, missing or broken springs) is a death sentence for this mechanism.
Except for the removable one up by the Governor, these Yak 52 cooling vanes work in pairs, linked by an extension spring.
These springs and their clips are attached on the rear of the cooling vanes’ disc though, so unless you routinely pop the cowling halves open, it’s tough to include them in your Daily Inspection…but ignore their condition at your peril!
Are you running out of Clip Real Estate?
The rubberized sewn Chafing strip between the cowling halves is meant to be held down by riveted oval fishplates that center the axles.
It's not uncommon to see this chafing strip applied above the fishplates because of all the rivet removal required to do the job properly.
On the plus side though, if you can’t see the fishplates, you’ll never see the wear on the heads of the axles…
There - you fixed it!
Many of us drool over how Sukhoi approached the cooling problem with a disc iris, and vow to install one as soon as we win the lottery.
Sukhoi’s solution not only varies the cooled area without creating gaps between the iris blades, it directs air onto the hottest part first - the cylinder head - plus their design drastically reduced the number of moving parts.
However, even this solution has its detractors… More on these Irises another time.
On our pivoting Gills system, some kind of damping would be better than just those extension Springs alone, because dampers dissipate energy ( what we need) whereas Springs just store it and give it back a few milliseconds later, aka vibration….but damping components tend to be complicated and expensive.
TYC can’t fix that unfortunately, but we do have replacement Gill Shutter spring / brackets kits available.
Both the flat and the bent brackets are made of thicker steel than the factory original, case hardened for greater wear resistance and zinc plated for paint adhesion.
Installation rivets & backup washers are included plus a correctly sized Repro spring, made in…Kentucky.
Some random blog post isn’t going bring about a breakthrough lifestyle change to your pre-flight inspection habits…
But now with this kit, at least with respect to the springs and retainers in your Gill Shutter system you can...FUHGEDDABOUDIT
John flies out of KSEE whenever he can scrape together a few bucks to fill the tanks